Tsunami Hazard Map of Everett, Washington - Access Washington
WASHINGTON DIVISION OF GEOLOGY AND EARTH RESOURCES OPEN FILE REPORT 2014-03
NOAA Center for Tsunami Research Pacific Marine Environmental Laboratory
Tsunami Hazard Map of Everett, Washington December 2014
Tsunami Hazard Map of Everett, Washington: Model Results for Magnitude 7.3 and 6.7 Seattle Fault Earthquakes by Timothy J. Walsh1, Diego Arcas2, Vasily V. Titov2, and Chris C. Chamberlin2 1
Washington Division of Geology and Earth Resources, MS 47007, Olympia, WA 98504-7007; [email protected] 2 NOAA Center for Tsunami Research, NOAA/PMEL-UW/JISAO, 7600 Sand Point Way NE, Seattle, WA 98115
Mw 7.3
Mw 6.7
2 mi
area of Figures 1–4
Port Townsend 5
so u
ge
er
n Whidbey Island W hi
sl
t
an
d
f au
lt
un
2
zo
d
ne
1
Scenario A (Mw 7.3)
Scenario B (Mw 6.7)
1. Central Puget Sound
2 1
405
A1
A3
B1
B2
B1 Scenario B fault segments (Table 2) 1
0
A5 B4 5
2. Possession Sound
2 1
Bellevue
Mercer Island
A6 90
Newcastle Hills
Simulated tide gauge 5 mi
Figure 5. Location of study area, modeled segments of the Seattle fault, and simulated tide gauge stations used to model tsunami time-amplitude histories.
0 −1
3. Port Gardner east waterway
2 1 0
4. Snohomish channel entrance
2 1
−1
5. Central Snohomish channel
2 1 0 −1
0
0.5
1
1.5
2
2.5
3
Time (hours since event) Figure 6. Modeled tsunami amplitudes at the simulated tide gauges shown in Figure 5, arranged by proximity to the Seattle fault.
14 Ave NE
ey Eb ve
dw
ay
Al
oa Br N
Bla B ack c Hi Hili l Rd Rd
38th St NE
12th St NE
Ave
Broa dway
St
15th
St
19th
St
22nd
St
25th
St
Ferry Baker Is.
Spencer Island
4th St SE
12th St SE
Ave
Slip (m) 1.0 1.0 12.0 11.0 4.0 1.0
Scenario B. Seattle Fault Mw 6.7 Event This scenario along the Seattle fault is a modified version of the earthquake scenario used by the Earthquake Engineering Research Institute (EERI) and WAEMD for recent seismic hazard assessment studies (Stewart, 2005). This scenario represents a less severe, but more likely event than Scenario A. A Seattle fault earthquake Mw 6.5 or greater is forecast to have a 5 percent chance of occurrence over a 50-year period (Stewart, 2005). The scenario earthquake used in the EERI studies used a 24-km-long fault centered beneath the cities of Seattle and Bellevue; this resulted in little vertical deformation under the water of Puget Sound and minimized the effect of a potential tsunami. For the present study, the scenario was modified by shifting the event westward along the Seattle fault such that the fault begins at the western end of the original EERI fault and continues west under the central Puget Sound for 24 km (Fig. 5). This scenario uses a simplified fault model with a constant depth and dip angle and uniform 2.8 m vertical uplift derived by scaling down Scenario A to account for the overall smaller magnitude (Table 2). Table 2. Scenario B seismic fault parameters for a Seattle fault MW 6.7 earthquake, modified from the scenario earthquake used by EERI (Stewart, 2005). Strike is measured from north and dip direction is 90º perpendicular to thethe strike azimuth. clockwise from strike azimuth. Fault segment
Width (km)
Length (km)
Strike (deg)
Dip (deg)
Slip (m)
B1 B2 B3 B4
35.0 35.0 35.0 35.0
6.3 8.9 3.2 5.8
86.6 96.0 128.8 99.3
45.0 45.0 45.0 45.0
2.8 2.8 2.8 2.8
These thresholds were developed almost entirely from observations in ports and harbors and apply to newer harbor facilities. Older (40–50 year-old) or run-down facilities may have slightly lower thresholds (Rick Wilson, California Geological Survey, written commun., 2014). Figures 1–4 show depth of inundation and current velocity for the two scenarios.
St
Inferred AD 900 to 930 tsunami deposit
Figure 3
m
in
47° 57′ 32.05″ N 122° 14′ 25.70″ W
ki
l te
o B lvd
Ave
Ave SE
a
5
41st
43rd
r Te
2–3
Fede ral Ave
ve lA
Ave SE 43rd
0–2
Colby
Inundation Depth (feet)
1 mile
0
51st Ave SE
34th St
W
29th St SE
2
Pacific
Ch err y Ave
D i k e Rd
204
29th St SE
Ave 41st
63rd
5
rs
o
e
y s i d e B l vd
ew B l vd
Vi e in
ar
M W
Av
Su n n
I
Je tty
Possesion
Ch err y Ave
D i k e Rd
s
529
u
o B l vd
Ave
NE Hwy ic P a c if
Bla Bla ack ck H Hii l Rd Hil
y s i d e B l vd
Colby
Broa dway
American Legion Memorial Park
os
Maximum Current (knots)
St
0–3
M
l te
52nd A
Church Rd
Ave 63rd
Sound
ay dw oa Br N
Su n n
B l vd
Ave
R
Ebey Island
51st Ave NE
52nd A
NE Hwy ic P a c if
ew
o rs
204
Colby
Fede ral Ave
ve lA
Dip (deg) 60.0 60.0 60.0 60.0 60.0 60.0
“although damage in harbors might vary based on the age and location of docks and boats, some generalities about the relationship between tsunami currents and damage can be determined....there is a noticeable threshold for damage initiation at ~3 knots (1.5 m/s). When 3 knots is exceeded, the predicted damage state switches from no damage to minor to moderate damage. Thus, in the simulated data, 3 knots represents the first important current velocity threshold. We then argue that the second threshold is at 6 knots (3 m/s), where damage transitions from moderate to major. A third current speed threshold is less clear, but is logically around 9 knots (4.5 m/s).”
−1
0
been trenched in central Puget Sound were generated by bedding-plane slip on reverse faults—which can rupture independently of the master Seattle fault—and they proposed that the Seattle fault zone is a wedge thrust, with the northern, leading edge being a fault-bend wedge-thrust fold. There also is substantial evidence that earthquakes on the Seattle fault have generated tsunamis. Atwater and Moore (1992) showed that tsunamis inundated part of Whidbey Island and West Point about 1000 years ago (Figure 5). Jacoby and others (1992) further showed that a tree in the tsunami deposit at West Point died the same season of the same year as a drowned forest carried into Lake Washington by a huge landslide from Mercer Island, strongly implicating the AD 900 to 930 seismic event on the Seattle fault. A discontinuous sand layer along
0.5
Maximum inundation depth and current velocity are model outputs and are displayed on Figures 1 through 4. The depth intervals chosen for Figure 1 (0–2 ft, 2–6 ft, and 6–8 ft) broadly represent hazard to people—inundation up to an adult’s knees, from the knees to the head, and over the head. The modeling for Scenario B yielded a maximum inundation depth of 3 ft. Note that tide flats are shown in the aerial photo base maps—but are assumed to be underwater in the model—because the initial model conditions assume that the tide stage is at mean high water. Current velocities are given in knots following Lynett and others’ (2014, p. 2049–2050) proposed damage thresholds. They state:
n
A4 B3
Restoration Point
A1 Scenario A fault segments (Table 1)
gto
ttle fau lt
A2
Bremerton
Seattle
Wave amplitude (m)
modeled Sea
s h in
od
West Point
L a k e Wa
Ho
C
−1 Bainbridge Island
0
RESULTS
0
l ana
Vi e in
ar
M W
Ch err y Ave
D i k e Rd Ave SE 43rd
This scenario is identical to the Seattle fault scenario defined by Titov and others (2003) and was also previously used for modeling inundation in Tacoma (Venturato and others, 2007). This scenario was designed to be a maximum credible event and uses the vertical deformation constraints from the AD 900 to 930 earthquake along the Seattle fault (Bucknam and others, 1992). It is described by six fault segments of varying length and strike, with slip ranging from 1 to 12 m (Table 1).
u
u
M
Scenario A. Seattle Fault Mw 7.3 Event
Everett
I ey db
Pu
101
th
ve Colby
Broa dway
Possesion
Ave
Ave Colby
Fede ral Ave
ve lA
1
2
Eb
I
Je tty
y s i d e B l vd
Sound
ay dw oa Br N
Su n n
B l vd
o rs ve
Church Rd
Ave 63rd
Black Bla ackk Hi Hilll R H Rd d
Hwy ic P a c if
ew
Vi e in
ar
M W
Ch err y Ave
D i k e Rd
io
ss se
Po s
5
Everett tide gauge
51st Ave NE
52nd A
NE
I
Je tty
Possesion
14 Ave NE
ey
ey Blla Bla ack c Hil Hillll R Rd d
y s i d e B l vd
Colby
Broa dway
Ave SE 43rd
3
Al
14 Ave NE
Church Rd
Ave 63rd
Sound
ay dw oa Br N
Su n n
B l vd
o rs ve Ave Colby
Ave Colby
Fede ral Ave M
u
51st Ave NE
52nd A
NE Hwy ic P a c if
ew
Vi e in
ar
M W Al
51st Ave NE
I
Je tty ve
Eb
Eb
Church Rd
Sound Possesion lA
Al
14 Ave NE
ey
Everett
4
So
http://www.dnr.wa.gov/geology/
n
vd
0
The model of Titov and Synolakis (1998), also known as the Method of Splitting Tsunami (MOST) model (Titov and González, 1997), was used by NCTR modelers. It uses a grid of topographic and bathymetric elevations and calculates a wave elevation and depth-averaged velocity at each grid point at specified time intervals to simulate the generation, propagation, and inundation of tsunamis. In this MOST model study, two deformation models for the Seattle fault were used: Scenario A simulates the AD 900 to 930 event as a credible worst-case scenario of magnitude Mw 7.3. Scenario B simulates a less severe, but more likely Mw 6.7 event. Details of the Seattle fault scenarios are given in Titov and others (2003) and Walsh and others (2003c). The fault parameters (Tables 1 and 2) were derived in a workshop convened by Walsh and attended by T. M. Brocher, T. L. Pratt, B. L. Sherrod, and C. S. Weaver, all from the USGS, and Diego Arcas, F. I. González, H. O. Mofjeld, V. V. Titov, and A. J. Venturato, all from NOAA. The seismic parameters from this workshop were simplified from the rupture models discussed above but are broadly in agreement. Time-amplitude histories for scenario tsunamis were generated for five simulated tide gauges and are shown on Figures 5 and 6.
5
2
PALEOSEISMOLOGY OF THE SEATTLE FAULT Geographic features now known to be associated with the Seattle fault have been noted for many years. In his journal entry for May 29, 1792, Vancouver (1798) noted that the fault-uplifted and wavecut bedrock platform at Restoration Point on Bainbridge Island “did not possess that beautiful variety of landscape, being an almost impenetrable wilderness of lofty trees” that characterized the rest of his explorations in Puget Sound. Kimball (1897) also noted the uplifted wavecut platform at Restoration Point, measured its height, and identified the marine fossils found there. He also described the Newcastle Hills, part of the hanging wall of the fault, as a ‘postglacial eruption’. Daneš and others (1965) interpreted the large gravity and magnetic anomalies through central Puget Sound, and an associated abrupt change in sedimentary section thickness, as an active fault with about 11 km of displacement. Rogers (1970) collected additional gravity and magnetic data across the structure and named it the Seattle–Bremerton fault. Gower (1978) demonstrated that the uplift at Restoration Point was Holocene in age and Bucknam and others (1992) showed that an earthquake produced 7 m of uplift on the fault about 1000 years ago (Sherrod and others, 2000), probably between AD 900 and 930 (Atwater, 1999), and hereafter referred to as the AD 900 to 930 event. In 1996, the first of a series of lidar (Light Detection and Ranging) surveys was flown over Bainbridge Island. This and subsequent lidar missions have enabled scientists to accurately locate expressions of the Seattle fault in a number of places and to site paleoseismic trenches across those faults in order to determine fault age and potential recurrence intervals (Bucknam and others, 1999; Nelson and others, 2002). At about the same time, the USGS began several large-scale geophysical studies. An aeromagnetic study of the Puget Sound (Blakely and others, 1999, 2002) enabled more accurate location of the fault along its entire length. Seismic studies, such as SHIPS (Seismic Hazards Investigations in Puget Sound; Brocher and others, 2001) and other geophysical studies in Puget Sound, have greatly increased the understanding of the fault at depth (Pratt and others, 1997; Johnson and others, 1999; ten Brink and others, 2002; Brocher and others, 2004). Later, ten Brink and others (2006) evaluated existing fault models by using uplifted shorelines and concluded that the best-fitting model geometry is a south-dipping reverse fault with a shallow roof ramp consisting of at least two back thrusts. Kelsey and others (2008) suggested that some of the scarps that have
So
MODELING
d un
Bl
0.5
Table 1. Scenario A seismic fault parameters for a Seattle fault MW 7.3 earthquake, after Titov and others (2003). Strike is measured from north and dip direction is 90º perpendicular clockwise the strike azimuth. to the strikefrom azimuth. Strike (deg) 87.9 86.6 96.0 128.8 99.3 81.0
ide
1
Length (km) 15.2 6.3 8.9 3.2 11.5 14.9
ys
47° 57′ 32.05″ N 122° 14′ 25.70″ W
ki
h
EVERETT
Naval Station Everett
12th St SE
5
ug
S o p e r H ill Rd
mi sh
12 t h
Ave
SCALE 1:32,000
Width (km) 35.0 35.0 35.0 35.0 35.0 35.0
nn
Gedney (Hat) Island
a
S lo
St
4th St SE
St
Su
9–10 (near Naval Station Everett)
Fault segment A1 A2 A3 A4 A5 A6
bia Ave lum
sh mi lta o oh de S n ve r Ri
m
6–9
W
Co
In 1995, Congress directed the National Oceanic and Atmospheric Administration (NOAA) to develop a plan to protect the West Coast from locally generated tsunamis. A panel of representatives from NOAA, the Federal Emergency Management Agency, the U.S. Geological Survey (USGS), and the five Pacific coast states wrote the plan and submitted it to Congress, which created the National Tsunami Hazard Mitigation Program (NTHMP) in October 1996. The NTHMP is a program designed to reduce the impact of tsunamis through warning guidance, hazard assessment, and mitigation. A key component of the hazard assessment for tsunamis is delineation of areas subject to tsunami inundation. These maps are produced using computer models of earthquake-generated tsunamis from nearby seismic sources. The modeling for this map was performed by the NOAA Center for Tsunami Research (NCTR) at NOAA’s Pacific Marine Environmental Laboratory (PMEL) in Seattle and the results are shown in Figures 1 through 4. This map is part of a series of tsunami inundation maps produced by the Washington Division of Geology and Earth Resources (WADGER), in cooperation with the Washington Emergency Management Division (WAEMD), as a contribution to the NTHMP. Completed maps are the southern Washington coast (Walsh and others, 2000), Port Angeles (Walsh and others, 2002a), Port Townsend (Walsh and others, 2002b), Neah Bay (Walsh and others, 2003a), Quileute area (Walsh and others, 2003b), Seattle (Walsh and others, 2003c), Bellingham (Walsh and others, 2004), Anacortes–Whidbey Island (Walsh and others, 2005), and Tacoma (Walsh and others, 2009).
St
n
Line Rd
r
r Te
in
St
Snohomish delta distributaries—Ebey Slough, Steamboat Slough, Union Slough, and the Snohomish River—was probably also deposited by the tsunami from the AD 900 to 930 earthquake (Bourgeois and Johnson, 2001). The locations of these deposits are shown in Figures 1 and 3.
22nd
52nd Ave NE
NE
R i ve
3–6
1
Marysville
St
oat
gh
34th St
Figure 2
INTRODUCTION
19th
Spencer Island
Maximum Current (knots) 0–3
Figure 1
St
Ferry Baker Is.
od D r
47° 57′ 32.05″ N 122° 14′ 25.70″ W
12th St NE
Port Gardner
gwo
41st
o B l vd
15th
E
Dr
10th
St
Pl N
a mb
529
S n oh o
d an sl
Do
W
l te ki
Smith Island
S te
51st Ave SE
od D r
Inferred AD 900 to 930 tsunami deposit
38th St NE
2
gwo
od D r
od D r
St
e
ve N E
l NE
on ou
m
h
3 8th
St
Pacific
5
Snohomish River delta
hP
Sl
r Te
a
Av
529
Do
(near Naval 6–8 Station Everett)
in
ug
Un i
Rd
2–6
40 t
side
34th St
0–2
s
5
25th
Ave
Inundation Depth (feet)
Ebey Island
29th St SE
2
S lo
EVERETT
Naval Station Everett
204
51st Ave SE
American Legion Memorial Park
12 t h
12th St SE
29th St SE
Pacific
n
4th St SE
St
oat
48° 03′ 03.35″ N 122° 07′ 51.55″ W
Sundown Rd
28th Pl
mi sh os
a
e r in
River
St
vd
22nd
Bl
St
ide
19th
Spencer Island
529
Ave
5
41st
St
25th
Naval Station Everett
gwo
gwo o B l vd
15th
M
Line Rd
r
204
Do
Do 47° 57′ 32.05″ N 122° 14′ 25.70″ W
l te
Ferry Baker Is.
52nd Ave NE
S o p e r H ill Rd
R
ugh
NE
R i ve
St
51st Ave SE
ki
Port Gardner
10th
12th St SE
2
m
12th St NE
St
E
Dr
St
4th St SE
529
34th St
38th St NE
EVERETT 25th
Pacific
e 5
12 t h
EVERETT
Naval Station Everett
Av
a mb
529
S n oh o
d an sl
S lo
PRIEST POINT S te
MARYSVILLE
529
Dr
l NE
Rd
St
Smith Island
Pl N
side
22nd
American Legion Memorial Park
3 8th
River
St
h
r
19th
Spencer Island
s
R i ve
St
Ferry Baker Is.
os
Rd
15th
R
n
Snohomish River delta
hP
on
28th Pl
Ebey Island
side
Rd
12th St NE
Port Gardner
10th
St
ug
Un i
NE
mi sh
River
r
side
R i ve
38th St NE
40 t
S o p e r H ill Rd
Dr
St
12 t h
a in
d an sl
ys
e
S lo
48° 02′ 57.80″ N 122° 14′ 37.15″ W
nn
Av
5
River
10th
s
oat
Su
n
American Legion Memorial Park
os
amb
529
S n oh o
bia Ave lum
R
Ebey Island
Line Rd
ve N E
Sundown Rd
PRIEST POINT
on
E
a
gh
mi sh
M
l NE
S te
28th Pl
S o p e r H ill Rd
Dr
Port Gardner
Smith Island
Pl N
NE
529
S n oh o
52nd Ave NE
e r in
ou
h
3 8th
ugh
Sl
ug
Snohomish River delta
hP
gh
S lo
Un i
ou
oat
gh
28th Pl
d an sl
40 t
Sl
a mb
ve N E
Sundown Rd
PRIEST POINT
ou
E
in e
48° 03′ 03.35″ N 122° 07′ 51.55″ W
Co
S te
Sl
Pl N
Line Rd
l NE
on
vd
hP
ar
bia Ave lum
Un i
Smith Island
r Te
M
Dr
Co
52nd Ave NE
S lo
Maximum Current
MARYSVILLE
529
Bl
vd
PRIEST POINT
ough
ide
Bl
40 t
3 8th
Sl
Dr
ve N E
Sundown Rd
Snohomish River delta
529
48° 02′ 57.80″ N 122° 14′ 37.15″ W
48° 03′ 03.35″ N 122° 07′ 51.55″ W
ys
ide
a
bia Ave lum
M
e r in
MARYSVILLE
nn
ys
h lo u g Co
Dr
48° 02′ 57.80″ N 122° 14′ 37.15″ W
nn
S
48° 03′ 03.35″ N 122° 07′ 51.55″ W
Su
MARYSVILLE
529
Su
48° 02′ 57.80″ N 122° 14′ 37.15″ W
Modeled Inundation
Maximum Current
M
Modeled Inundation
W
Figure 4
1 kilometer
DISCUSSION One investigation has identified paleotsunami deposits in the Everett area. Bourgeois and Johnson (2001) identified numerous locations along sloughs of the Snohomish River delta that showed evidence of abrupt subsidence and an apparently continuous sheet of sand that overlies a soil dated to about AD 800–980 (Figs. 1 and 3), a range that completely contains the inferred age of the last Seattle fault earthquake (AD 900 to 930). These workers also found evidence for an older tsunami deposit (not shown on the figures) whose age is not well constrained. The tsunami model for Scenario A correlates well with all of the AD 900 to 930 tsunami deposit locations—the upstream extent of the model is approximately coincident with the most upstream tsunami deposits. However, because the sloughs are now protected by levees, the tsunami modeled here will behave differently from the AD 900 to 930 event even if the model perfectly matched the dynamics of that earthquake. Other potential tsunami sources for this area are not well enough understood to be included in this assessment. The southern Whidbey Island fault zone crosses Puget Sound a short distance south of Everett (Dragovich and others, 2002) but is not understood well enough to build a credible seismic scenario model. Tsunamis can also be caused by landslides, both subaqueous and subaerial. Historic landslide-induced tsunamis occurred multiple times in Lake Roosevelt, the impoundment behind Grand Coulee Dam (Lander and others, 1993), in the Tacoma tidal flats in 1894 (Kimball, 1897), the Tacoma Narrows in 1949 (González, 2003), and in the lower Columbia River in 1965 (Aberdeen Daily World, February 1, 1965). Shipman (2001) reported a landslide-induced tsunami generated from Camano Island that inundated a Native American village on Gedney (Hat) Island, probably early in the 19th century, as reconstructed from Native American oral history. Figure 7 shows the presumed landslide scar and the clearly vulnerable Gedney Island immediately to the south. While landslide sources clearly present at least a localized tsunami threat, modeling those tsunamis is beyond the scope of this effort.
Limitations of the Maps The largest source of uncertainty in these model results is the input earthquake event because the nature of the tsunami depends on the initial deformation. The earthquake scenarios used in this modeling were selected to honor the paleoseismic constraints, but the next Seattle fault earthquake may be substantially different from those that have been characterized. Sherrod and others (2000) show that a prior uplift event at Restoration Point (predating the AD 900 to 930 event) was smaller. Paleoseismic trenching of structures subsidiary to the Seattle fault—thought to be coseismic with the main fault trace (Nelson and Landslide on Camano Head Camano Island
Copyright © 1994–2014 Washington State Department of Ecology
Gedney (Hat) Island
Whidbey Island
Possession Sound
Imagery from 2011 Washington State NAIP
EVERETT
0
1
Figure 7. Historic landslide on Camano Head (inset, annotated) may have caused a tsunami at nearby Gedney (Hat) Island and inundated a Native American village.
2 miles
others, 2002)—indicates that there were at least two earthquakes in the 1500 years before the AD 900 to 930 event. These earthquakes, however, did not uplift prominent wavecut platforms similar to the one made by the AD 900 to 930 event, which suggests that not all earthquakes along the Seattle fault have the same amount of vertical or horizontal displacement. Kelsey and others (2008) suggested that at least some of the previous earthquakes may have been produced by bedding-plane slip on a fault-bend fold and were not located on the main Seattle fault at all. Another significant limitation is that the resolution of the modeling is no greater nor more accurate than the bathymetric and topographic data used—data cells are locally up to 50 m on a side. The models do not include the influences of changes in tides and are referenced to mean high water. The tide stage and tidal currents can amplify or reduce the impact of a tsunami on a specific community. At the Everett tide gage, the diurnal range (the difference in height between mean higher high water and mean lower low water) is about 11 ft (3.4 m) (accessed on August 8, 2014, at http://www.tidesandcurrents.noaa.gov). This means that, while the modeling can be a useful tool to guide evacuation planning, it is not of sufficient resolution to be useful for land-use planning.
ACKNOWLEDGMENTS This project was supported by NTHMP in cooperation with WAEMD. Information about NTHMP is available at http://nthmp.tsunami.gov/. During the study, NCTR maintained close communication with WAEMD and WADGER and, upon completion of the study, a suite of model-derived mapping products were delivered to both agencies in the form of electronic files and, where appropriate, hard copy representations. Reviews by Stephen Slaughter (WADGER) and John Schelling (WAEMD) were helpful.
REFERENCES Atwater, B. F., 1999, Radiocarbon dating of a Seattle earthquake to A.D. 900–930 [abstract]: Seismological Research Letters, v. 70, no. 2, p. 232. Atwater, B. F.; Moore, A. L., 1992, A tsunami about 1000 years ago in Puget Sound, Washington: Science, v. 258, no. 5088, p. 1614-1617. Blakely, R. J.; Wells, R. E.; Weaver, C. S., 1999, Puget Sound aeromagnetic maps and data: U.S. Geological Survey Open-File Report 99-514, version 1.0. [http://geopubs.wr.usgs.gov/ open-file/of99-514/] Blakely, R. J.; Wells, R. E.; Weaver, C. S.; Johnson, S. Y., 2002, Location, structure, and seismicity of the Seattle fault zone, Washington—Evidence from aeromagnetic anomalies, geologic mapping, and seismic-reflection data: Geological Society of America Bulletin, v. 114, no. 2, p. 169-177. Bourgeois, Joanne; Johnson, S. Y., 2001, Geologic evidence of earthquakes at the Snohomish delta, Washington, in the past 1200 yr: Geological Society of America Bulletin, v. 113, no. 4, p. 482-494. Brocher, T. M.; Blakely, R. J.; Wells, R. E., 2004, Interpretation of the Seattle uplift, Washington, as a passive-roof duplex: Seismological Society of America Bulletin, v. 94, no. 4, p. 1379-1401. Brocher, T. M.; Parsons, T. E.; Blakely, R. J.; Christensen, N. I.; Fisher, M. A.; Wells, R. E.; SHIPS Working Group, 2001, Upper crustal structure in Puget Lowland, Washington—Results from the 1998 Seismic Hazards Investigations in Puget Sound: Journal of Geophysical Research, v. 106, no. B7, p. 13,541-13,564. Bucknam, R. C.; Hemphill-Haley, Eileen; Leopold, E. B., 1992, Abrupt uplift within the past 1700 years at southern Puget Sound, Washington: Science, v. 258, no. 5088, p. 1611-1614. Bucknam, R. C.; Sherrod, B. L.; Elfendahl, G. W., 1999, A fault scarp of probable Holocene age in the Seattle fault zone, Bainbridge Island, Washington (abstract): Seismological Research Letters, v. 70, no. 2, p. 233. Daneš, Z. F.; Bonno, M.; Brau, J. E.; Gilham, W. D.; Hoffman, T. F.; Johansen, D.; Jones, M. H.; Malfait, Bruce; Masten, J.; Teague, G. O., 1965, Geophysical investigation of the southern Puget Sound area, Washington: Journal of Geophysical Research, v. 70, no. 22, p. 5573-5580. Dragovich, J. D.; Logan, R. L.; Schasse, H. W.; Walsh, T. J.; Lingley, W. S., Jr.; Norman, D. K.; Gerstel, W. J.; Lapen, T. J.; Schuster, J. E.; Meyers, K. D., 2002, Geologic map of Washington—Northwest quadrant: Washington Division of Geology and Earth Resources Geologic Map GM-50, 3 sheets, scale 1:250,000, with 72 p. text. [http://www.dnr.wa.gov/ Publications/ger_gm50_geol_map_nw_wa_250k.pdf] González, F. I., compiler, 2003, Puget Sound tsunami sources—2002 workshop report: NOAA/Pacific Marine Environmental Laboratory Contribution No. 2526, 36 p.
Gower, H. D., 1978, Tectonic map of the Puget Sound region, Washington, showing locations of faults, principal folds, and large-scale Quaternary deformation: U.S. Geological Survey Open-File Report 78-426, 22 p., 1 plate, scale 1:250,000. Jacoby, G. C.; Williams, P. L.; Buckley, B. M., 1992, Tree ring correlation between prehistoric landslides and abrupt tectonic events in Seattle, Washington: Science, v. 258, no. 5088, p. 1621-1623. Johnson, S. Y.; Dadisman, S. V.; Childs, J. R.; Stanley, W. D., 1999, Active tectonics of the Seattle fault and central Puget Sound, Washington—Implications for earthquake hazards: Geological Society of America Bulletin, v. 111, no. 7, p. 1042-1053, 1 plate. Kelsey, H. M.; Sherrod, B. L.; Nelson, A. R.; Brocher, T. M., 2008, Earthquakes generated from bedding plane-parallel reverse faults above an active wedge thrust, Seattle fault zone: Geological Society of America Bulletin, v. 120, no. 11-12, p. 1581-1597. Kimball, J. P., 1897, Physiographic geology of the Puget Sound basin (in 2 parts): American Geologist, v. 19, no. 4, p. 225-237 (part 1); v. 19, no. 5, p. 304-322 (part 2). Lander, J. F.; Lockridge, P. A.; Kozuch, M. J., 1993, Tsunamis affecting the west coast of the United States, 1806-1992: U.S. National Geophysical Data Center Key to Geophysical Records Documentation 29, 243 p. Lynett, P. J.; Borrero, Jose; Son, Sangyoung; Wilson, Rick; K. Miller, Kevin, 2014, Assessment of the tsunami-induced current hazard, Geophysical Research Letters, v. 41, n. 6, p. 2048–2055. doi:10.1002/2013GL058680. Nelson, A. R.; Johnson, S. Y.; Wells, R. E.; Pezzopane, S. K.; Kelsey, H. M.; Sherrod, B. L.; Bradley, L.-A.; Koehler, R. D., III; Bucknam, R. C.; Haugerud, R. A.; Laprade, W. T., 2002, Field and laboratory data from an earthquake history study of the Toe Jam Hill fault, Bainbridge Island, Washington: U.S. Geological Survey Open-File Report 02-60, 1 v., 2 plates. [http://pubs.usgs.gov/of/2002/ofr-02-0060/] Pratt, T. L.; Johnson, S. Y.; Potter, C. J.; Stephenson, W. J.; Finn, C. A., 1997, Seismic reflection images beneath Puget Sound, western Washington State—The Puget Lowland thrust sheet hypothesis: Journal of Geophysical Research, v. 102, no. B12, p. 27,469-27,489. Rogers, W. P., 1970, A geological and geophysical study of the central Puget Sound lowland: University of Washington Doctor of Philosophy thesis, 123 p., 9 plates. Sherrod, B. L.; Bucknam, R. C.; Leopold, E. B., 2000, Holocene relative sea level changes along the Seattle fault at Restoration Point, Washington: Quaternary Research, v. 54, no. 3, p. 384-393. Shipman, Hugh, 2001, The fall of Camano Head—A Snohomish account of a large landslide and tsunami in Possession Sound during the early 1800s: TsuInfo Alert, v. 3, no. 6, p. 13-14. [http://www.dnr.wa.gov/Publications/ger_tsuinfo_2001_v3_no6.pdf] Stewart, Mark, editor, 2005, Scenario for a magnitude 6.7 earthquake on the Seattle Fault: Earthquake Engineering Research Institute and Washington Military Department Emergency Management Division, 162 p. ten Brink, U. S.; Molzer, P. C.; Fisher, M. A.; Blakely, R. J.; Bucknam, R. C.; Parsons, T. E.; Crosson, R. S.; Creager, K. C., 2002, Subsurface geometry and evolution of the Seattle fault zone and the Seattle basin, Washington: Seismological Society of America Bulletin, v. 92, no. 5, p. 1737-1753. ten Brink, U. S.; Song, Jianli; Bucknam, R. C., 2006, Rupture models for the A.D. 900–930 Seattle fault earthquake from uplifted shorelines: Geology, v. 34, no. 7, p. 585-588. Titov, V. V.; González, F. I., 1997, Implementation and testing of the Method of Splitting Tsunami (MOST) model: NOAA Technical Memorandum ERL PMEL-112, PB98-122773, 11 p. Titov, V. V.; González, F. I.; Mofjeld, H. O.; Venturato, A. J., 2003, NOAA TIME Seattle tsunami mapping project—Procedures, data sources, and products: NOAA Technical Memorandum OAR PMEL-124, 21 p. Titov, V. V.; Synolakis, C. E., 1998, Numerical modeling of tidal wave run up: Journal of Waterway, Port, Coastal and Ocean Engineering, v. 124, n. 4, p. 157–171. Vancouver, George, 1798, repr. 1992, A voyage of discovery to the north Pacific Ocean, and round the world; in which the coast of north-west American has been carefully examined and accurately surveyed—Undertaken by His Majesty's command, principally with a view to ascertain the existence of any navigable communication between the north Pacific and north Atlantic Oceans; and performed in the years 1790, 1791, 1792, 1793, 1794, and 1795: G. G. and J. Robinson [London], 3 v. Venturato, A. J.; Arcas, Diego; Titov, V. V.; Mofjeld, H. O.; Chamberlin, C. C.; González, F. I., 2007, Tacoma, Washington, tsunami hazard mapping project— Modeling tsunami inundation from Tacoma and Seattle fault earthquakes: National Oceanic and Atmospheric Administration, Pacific Marine Environmental Laboratory Technical Memorandum OAR-PMEL-132, 23 p. Walsh, T. J.; Arcas, Diego; Venturato, A. J.; Titov, V. V.; Mofjeld, H. O.; Chamberlin, C. C.; González, F. I., 2009, Tsunami hazard map of Tacoma, Washington—Model results for Seattle fault and Tacoma fault earthquake tsunamis: Washington Division of Geology and Earth Resources Open File Report 2009-9, 1 sheet, scale 1:24,000. [http://www.dnr.wa.gov/ publications/ger_ofr2009-9_tsunami_hazard_tacoma.pdf]
Walsh, T. J.; Caruthers, C. G.; Heinitz, A. C.; Myers, E. P., III; Baptista, A. M.; Erdakos, G. B.; Kamphaus, R. A., 2000, Tsunami hazard map of the southern Washington coast—Modeled tsunami inundation from a Cascadia subduction zone earthquake: Washington Division of Geology and Earth Resources Geologic Map GM-49, 1 sheet, scale 1:100,000, with 12 p. text. [http://www.dnr.wa.gov/publications/ ger_gm49_tsunami_hazard_southern_coast.zip] Walsh, T. J.; Myers, E. P., III; Baptista, A. M., 2002a, Tsunami inundation map of the Port Angeles, Washington area: Washington Division of Geology and Earth Resources Open File Report 2002-1, 1 sheet, scale 1:24,000. [http://www.dnr.wa.gov/publications/ger_ofr2002-1_ tsunami_hazard_portangeles.pdf] Walsh, T. J.; Myers, E. P., III; Baptista, A. M., 2002b, Tsunami inundation map of the Port Townsend, Washington area: Washington Division of Geology and Earth Resources Open File Report 2002-2, 1 sheet, scale 1:24,000. [http://www.dnr.wa.gov/publications/ ger_ofr2002-2_tsunami_hazard_porttownsend.pdf] Walsh, T. J.; Myers, E. P., III; Baptista, A. M., 2003a, Tsunami inundation map of the Neah Bay, Washington, area: Washington Division of Geology and Earth Resources Open File Report 2003-2, 1 sheet, scale 1:24,000. [http://www.dnr.wa.gov/publications/ger_ofr2003-2_tsunami_ hazard_neahbay.pdf] Walsh, T. J.; Myers, E. P., III; Baptista, A. M., 2003b, Tsunami inundation map of the Quileute, Washington, area: Washington Division of Geology and Earth Resources Open File Report 2003-1, 1 sheet, scale 1:24,000. [http://www.dnr.wa.gov/publications/ger_ofr2003-1_tsunami_ hazard_quileute.pdf] Walsh, T. J.; Titov, V. V.; Venturato, A. J.; Mofjeld, H. O.; González, F. I., 2003c, Tsunami hazard map of the Elliott Bay area, Seattle, Washington—Modeled tsunami inundation from a Seattle fault earthquake: Washington Division of Geology and Earth Resources Open File Report 2003-14, 1 sheet, scale 1:50,000. [http://www.dnr.wa.gov/publications/ger_ofr2003-14_ tsunami_hazard_elliottbay.pdf] Walsh, T. J.; Titov, V. V.; Venturato, A. J.; Mofjeld, H. O.; González, F. I., 2004, Tsunami hazard map of the Bellingham area, Washington—Modeled tsunami inundation from a Cascadia subduction zone earthquake: Washington Division of Geology and Earth Resources Open File Report 2004-15, 1 sheet, scale 1:50,000. [http://www.dnr.wa.gov/publications/ger_ofr2004-15_ tsunami_hazard_bellingham.pdf] Walsh, T. J.; Titov, V. V.; Venturato, A. J.; Mofjeld, H. O.; González, F. I., 2005, Tsunami hazard map of the Anacortes–Whidbey Island area, Washington—Modeled tsunami inundation from a Cascadia subduction zone earthquake: Washington Division of Geology and Earth Resources Open File Report 2005-1, 1 sheet, scale 1:62,500. [http://www.dnr.wa.gov/ publications/ger_ofr2005-1_tsunami_hazard_anacortes_whidbey.pdf]
Suggested citation: Walsh, T. J.; Arcas, Diego; Titov, V. V.; Chamberlin, C. C., 2014, Tsunami hazard map of Everett, Washington: model results for magnitude 7.3 and 6.7 Seattle fault earthquake tsunamis: Washington Division of Geology and Earth Resources Open File Report 2014-03, 1 sheet, scale 1:32,000. Disclaimer: This product is provided ‘as is’ without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular use. The Washington Department of Natural Resources and the authors of this product will not be liable to the user of this product for any activity involving the product with respect to the following: (a) lost profits, lost savings, or any other consequential damages; (b) fitness of the product for a particular purpose; or (c) use of the product or results obtained from use of the product. This product is considered to be exempt from the Geologist Licensing Act [RCW 18.220.190 (4)] because it is geological research conducted by the State of Washington, Department of Natural Resources, Division of Geology and Earth Resources.
Base map from 2011 Snohomish County NAIP color 3-foot-resolution aerial photos HARN State Plane coordinate system, Washington South FIPS 4602 North American Datum of 1983 Shaded relief generated from U.S. Geological Survery 10-meter digital elevation model Digital cartography by Anne C. Olson Editing and production by Alexander N. Steely and Jaretta M. Roloff
© 2014 Washington Division of Geology and Earth Resources
NOAA Center for Tsunami Research Pacific Marine Environmental Laboratory
Tsunami Hazard Map of Everett, Washington December 2014
Tsunami Hazard Map of Everett, Washington: Model Results for Magnitude 7.3 and 6.7 Seattle Fault Earthquakes by Timothy J. Walsh1, Diego Arcas2, Vasily V. Titov2, and Chris C. Chamberlin2 1
Washington Division of Geology and Earth Resources, MS 47007, Olympia, WA 98504-7007; [email protected] 2 NOAA Center for Tsunami Research, NOAA/PMEL-UW/JISAO, 7600 Sand Point Way NE, Seattle, WA 98115
Mw 7.3
Mw 6.7
2 mi
area of Figures 1–4
Port Townsend 5
so u
ge
er
n Whidbey Island W hi
sl
t
an
d
f au
lt
un
2
zo
d
ne
1
Scenario A (Mw 7.3)
Scenario B (Mw 6.7)
1. Central Puget Sound
2 1
405
A1
A3
B1
B2
B1 Scenario B fault segments (Table 2) 1
0
A5 B4 5
2. Possession Sound
2 1
Bellevue
Mercer Island
A6 90
Newcastle Hills
Simulated tide gauge 5 mi
Figure 5. Location of study area, modeled segments of the Seattle fault, and simulated tide gauge stations used to model tsunami time-amplitude histories.
0 −1
3. Port Gardner east waterway
2 1 0
4. Snohomish channel entrance
2 1
−1
5. Central Snohomish channel
2 1 0 −1
0
0.5
1
1.5
2
2.5
3
Time (hours since event) Figure 6. Modeled tsunami amplitudes at the simulated tide gauges shown in Figure 5, arranged by proximity to the Seattle fault.
14 Ave NE
ey Eb ve
dw
ay
Al
oa Br N
Bla B ack c Hi Hili l Rd Rd
38th St NE
12th St NE
Ave
Broa dway
St
15th
St
19th
St
22nd
St
25th
St
Ferry Baker Is.
Spencer Island
4th St SE
12th St SE
Ave
Slip (m) 1.0 1.0 12.0 11.0 4.0 1.0
Scenario B. Seattle Fault Mw 6.7 Event This scenario along the Seattle fault is a modified version of the earthquake scenario used by the Earthquake Engineering Research Institute (EERI) and WAEMD for recent seismic hazard assessment studies (Stewart, 2005). This scenario represents a less severe, but more likely event than Scenario A. A Seattle fault earthquake Mw 6.5 or greater is forecast to have a 5 percent chance of occurrence over a 50-year period (Stewart, 2005). The scenario earthquake used in the EERI studies used a 24-km-long fault centered beneath the cities of Seattle and Bellevue; this resulted in little vertical deformation under the water of Puget Sound and minimized the effect of a potential tsunami. For the present study, the scenario was modified by shifting the event westward along the Seattle fault such that the fault begins at the western end of the original EERI fault and continues west under the central Puget Sound for 24 km (Fig. 5). This scenario uses a simplified fault model with a constant depth and dip angle and uniform 2.8 m vertical uplift derived by scaling down Scenario A to account for the overall smaller magnitude (Table 2). Table 2. Scenario B seismic fault parameters for a Seattle fault MW 6.7 earthquake, modified from the scenario earthquake used by EERI (Stewart, 2005). Strike is measured from north and dip direction is 90º perpendicular to thethe strike azimuth. clockwise from strike azimuth. Fault segment
Width (km)
Length (km)
Strike (deg)
Dip (deg)
Slip (m)
B1 B2 B3 B4
35.0 35.0 35.0 35.0
6.3 8.9 3.2 5.8
86.6 96.0 128.8 99.3
45.0 45.0 45.0 45.0
2.8 2.8 2.8 2.8
These thresholds were developed almost entirely from observations in ports and harbors and apply to newer harbor facilities. Older (40–50 year-old) or run-down facilities may have slightly lower thresholds (Rick Wilson, California Geological Survey, written commun., 2014). Figures 1–4 show depth of inundation and current velocity for the two scenarios.
St
Inferred AD 900 to 930 tsunami deposit
Figure 3
m
in
47° 57′ 32.05″ N 122° 14′ 25.70″ W
ki
l te
o B lvd
Ave
Ave SE
a
5
41st
43rd
r Te
2–3
Fede ral Ave
ve lA
Ave SE 43rd
0–2
Colby
Inundation Depth (feet)
1 mile
0
51st Ave SE
34th St
W
29th St SE
2
Pacific
Ch err y Ave
D i k e Rd
204
29th St SE
Ave 41st
63rd
5
rs
o
e
y s i d e B l vd
ew B l vd
Vi e in
ar
M W
Av
Su n n
I
Je tty
Possesion
Ch err y Ave
D i k e Rd
s
529
u
o B l vd
Ave
NE Hwy ic P a c if
Bla Bla ack ck H Hii l Rd Hil
y s i d e B l vd
Colby
Broa dway
American Legion Memorial Park
os
Maximum Current (knots)
St
0–3
M
l te
52nd A
Church Rd
Ave 63rd
Sound
ay dw oa Br N
Su n n
B l vd
Ave
R
Ebey Island
51st Ave NE
52nd A
NE Hwy ic P a c if
ew
o rs
204
Colby
Fede ral Ave
ve lA
Dip (deg) 60.0 60.0 60.0 60.0 60.0 60.0
“although damage in harbors might vary based on the age and location of docks and boats, some generalities about the relationship between tsunami currents and damage can be determined....there is a noticeable threshold for damage initiation at ~3 knots (1.5 m/s). When 3 knots is exceeded, the predicted damage state switches from no damage to minor to moderate damage. Thus, in the simulated data, 3 knots represents the first important current velocity threshold. We then argue that the second threshold is at 6 knots (3 m/s), where damage transitions from moderate to major. A third current speed threshold is less clear, but is logically around 9 knots (4.5 m/s).”
−1
0
been trenched in central Puget Sound were generated by bedding-plane slip on reverse faults—which can rupture independently of the master Seattle fault—and they proposed that the Seattle fault zone is a wedge thrust, with the northern, leading edge being a fault-bend wedge-thrust fold. There also is substantial evidence that earthquakes on the Seattle fault have generated tsunamis. Atwater and Moore (1992) showed that tsunamis inundated part of Whidbey Island and West Point about 1000 years ago (Figure 5). Jacoby and others (1992) further showed that a tree in the tsunami deposit at West Point died the same season of the same year as a drowned forest carried into Lake Washington by a huge landslide from Mercer Island, strongly implicating the AD 900 to 930 seismic event on the Seattle fault. A discontinuous sand layer along
0.5
Maximum inundation depth and current velocity are model outputs and are displayed on Figures 1 through 4. The depth intervals chosen for Figure 1 (0–2 ft, 2–6 ft, and 6–8 ft) broadly represent hazard to people—inundation up to an adult’s knees, from the knees to the head, and over the head. The modeling for Scenario B yielded a maximum inundation depth of 3 ft. Note that tide flats are shown in the aerial photo base maps—but are assumed to be underwater in the model—because the initial model conditions assume that the tide stage is at mean high water. Current velocities are given in knots following Lynett and others’ (2014, p. 2049–2050) proposed damage thresholds. They state:
n
A4 B3
Restoration Point
A1 Scenario A fault segments (Table 1)
gto
ttle fau lt
A2
Bremerton
Seattle
Wave amplitude (m)
modeled Sea
s h in
od
West Point
L a k e Wa
Ho
C
−1 Bainbridge Island
0
RESULTS
0
l ana
Vi e in
ar
M W
Ch err y Ave
D i k e Rd Ave SE 43rd
This scenario is identical to the Seattle fault scenario defined by Titov and others (2003) and was also previously used for modeling inundation in Tacoma (Venturato and others, 2007). This scenario was designed to be a maximum credible event and uses the vertical deformation constraints from the AD 900 to 930 earthquake along the Seattle fault (Bucknam and others, 1992). It is described by six fault segments of varying length and strike, with slip ranging from 1 to 12 m (Table 1).
u
u
M
Scenario A. Seattle Fault Mw 7.3 Event
Everett
I ey db
Pu
101
th
ve Colby
Broa dway
Possesion
Ave
Ave Colby
Fede ral Ave
ve lA
1
2
Eb
I
Je tty
y s i d e B l vd
Sound
ay dw oa Br N
Su n n
B l vd
o rs ve
Church Rd
Ave 63rd
Black Bla ackk Hi Hilll R H Rd d
Hwy ic P a c if
ew
Vi e in
ar
M W
Ch err y Ave
D i k e Rd
io
ss se
Po s
5
Everett tide gauge
51st Ave NE
52nd A
NE
I
Je tty
Possesion
14 Ave NE
ey
ey Blla Bla ack c Hil Hillll R Rd d
y s i d e B l vd
Colby
Broa dway
Ave SE 43rd
3
Al
14 Ave NE
Church Rd
Ave 63rd
Sound
ay dw oa Br N
Su n n
B l vd
o rs ve Ave Colby
Ave Colby
Fede ral Ave M
u
51st Ave NE
52nd A
NE Hwy ic P a c if
ew
Vi e in
ar
M W Al
51st Ave NE
I
Je tty ve
Eb
Eb
Church Rd
Sound Possesion lA
Al
14 Ave NE
ey
Everett
4
So
http://www.dnr.wa.gov/geology/
n
vd
0
The model of Titov and Synolakis (1998), also known as the Method of Splitting Tsunami (MOST) model (Titov and González, 1997), was used by NCTR modelers. It uses a grid of topographic and bathymetric elevations and calculates a wave elevation and depth-averaged velocity at each grid point at specified time intervals to simulate the generation, propagation, and inundation of tsunamis. In this MOST model study, two deformation models for the Seattle fault were used: Scenario A simulates the AD 900 to 930 event as a credible worst-case scenario of magnitude Mw 7.3. Scenario B simulates a less severe, but more likely Mw 6.7 event. Details of the Seattle fault scenarios are given in Titov and others (2003) and Walsh and others (2003c). The fault parameters (Tables 1 and 2) were derived in a workshop convened by Walsh and attended by T. M. Brocher, T. L. Pratt, B. L. Sherrod, and C. S. Weaver, all from the USGS, and Diego Arcas, F. I. González, H. O. Mofjeld, V. V. Titov, and A. J. Venturato, all from NOAA. The seismic parameters from this workshop were simplified from the rupture models discussed above but are broadly in agreement. Time-amplitude histories for scenario tsunamis were generated for five simulated tide gauges and are shown on Figures 5 and 6.
5
2
PALEOSEISMOLOGY OF THE SEATTLE FAULT Geographic features now known to be associated with the Seattle fault have been noted for many years. In his journal entry for May 29, 1792, Vancouver (1798) noted that the fault-uplifted and wavecut bedrock platform at Restoration Point on Bainbridge Island “did not possess that beautiful variety of landscape, being an almost impenetrable wilderness of lofty trees” that characterized the rest of his explorations in Puget Sound. Kimball (1897) also noted the uplifted wavecut platform at Restoration Point, measured its height, and identified the marine fossils found there. He also described the Newcastle Hills, part of the hanging wall of the fault, as a ‘postglacial eruption’. Daneš and others (1965) interpreted the large gravity and magnetic anomalies through central Puget Sound, and an associated abrupt change in sedimentary section thickness, as an active fault with about 11 km of displacement. Rogers (1970) collected additional gravity and magnetic data across the structure and named it the Seattle–Bremerton fault. Gower (1978) demonstrated that the uplift at Restoration Point was Holocene in age and Bucknam and others (1992) showed that an earthquake produced 7 m of uplift on the fault about 1000 years ago (Sherrod and others, 2000), probably between AD 900 and 930 (Atwater, 1999), and hereafter referred to as the AD 900 to 930 event. In 1996, the first of a series of lidar (Light Detection and Ranging) surveys was flown over Bainbridge Island. This and subsequent lidar missions have enabled scientists to accurately locate expressions of the Seattle fault in a number of places and to site paleoseismic trenches across those faults in order to determine fault age and potential recurrence intervals (Bucknam and others, 1999; Nelson and others, 2002). At about the same time, the USGS began several large-scale geophysical studies. An aeromagnetic study of the Puget Sound (Blakely and others, 1999, 2002) enabled more accurate location of the fault along its entire length. Seismic studies, such as SHIPS (Seismic Hazards Investigations in Puget Sound; Brocher and others, 2001) and other geophysical studies in Puget Sound, have greatly increased the understanding of the fault at depth (Pratt and others, 1997; Johnson and others, 1999; ten Brink and others, 2002; Brocher and others, 2004). Later, ten Brink and others (2006) evaluated existing fault models by using uplifted shorelines and concluded that the best-fitting model geometry is a south-dipping reverse fault with a shallow roof ramp consisting of at least two back thrusts. Kelsey and others (2008) suggested that some of the scarps that have
So
MODELING
d un
Bl
0.5
Table 1. Scenario A seismic fault parameters for a Seattle fault MW 7.3 earthquake, after Titov and others (2003). Strike is measured from north and dip direction is 90º perpendicular clockwise the strike azimuth. to the strikefrom azimuth. Strike (deg) 87.9 86.6 96.0 128.8 99.3 81.0
ide
1
Length (km) 15.2 6.3 8.9 3.2 11.5 14.9
ys
47° 57′ 32.05″ N 122° 14′ 25.70″ W
ki
h
EVERETT
Naval Station Everett
12th St SE
5
ug
S o p e r H ill Rd
mi sh
12 t h
Ave
SCALE 1:32,000
Width (km) 35.0 35.0 35.0 35.0 35.0 35.0
nn
Gedney (Hat) Island
a
S lo
St
4th St SE
St
Su
9–10 (near Naval Station Everett)
Fault segment A1 A2 A3 A4 A5 A6
bia Ave lum
sh mi lta o oh de S n ve r Ri
m
6–9
W
Co
In 1995, Congress directed the National Oceanic and Atmospheric Administration (NOAA) to develop a plan to protect the West Coast from locally generated tsunamis. A panel of representatives from NOAA, the Federal Emergency Management Agency, the U.S. Geological Survey (USGS), and the five Pacific coast states wrote the plan and submitted it to Congress, which created the National Tsunami Hazard Mitigation Program (NTHMP) in October 1996. The NTHMP is a program designed to reduce the impact of tsunamis through warning guidance, hazard assessment, and mitigation. A key component of the hazard assessment for tsunamis is delineation of areas subject to tsunami inundation. These maps are produced using computer models of earthquake-generated tsunamis from nearby seismic sources. The modeling for this map was performed by the NOAA Center for Tsunami Research (NCTR) at NOAA’s Pacific Marine Environmental Laboratory (PMEL) in Seattle and the results are shown in Figures 1 through 4. This map is part of a series of tsunami inundation maps produced by the Washington Division of Geology and Earth Resources (WADGER), in cooperation with the Washington Emergency Management Division (WAEMD), as a contribution to the NTHMP. Completed maps are the southern Washington coast (Walsh and others, 2000), Port Angeles (Walsh and others, 2002a), Port Townsend (Walsh and others, 2002b), Neah Bay (Walsh and others, 2003a), Quileute area (Walsh and others, 2003b), Seattle (Walsh and others, 2003c), Bellingham (Walsh and others, 2004), Anacortes–Whidbey Island (Walsh and others, 2005), and Tacoma (Walsh and others, 2009).
St
n
Line Rd
r
r Te
in
St
Snohomish delta distributaries—Ebey Slough, Steamboat Slough, Union Slough, and the Snohomish River—was probably also deposited by the tsunami from the AD 900 to 930 earthquake (Bourgeois and Johnson, 2001). The locations of these deposits are shown in Figures 1 and 3.
22nd
52nd Ave NE
NE
R i ve
3–6
1
Marysville
St
oat
gh
34th St
Figure 2
INTRODUCTION
19th
Spencer Island
Maximum Current (knots) 0–3
Figure 1
St
Ferry Baker Is.
od D r
47° 57′ 32.05″ N 122° 14′ 25.70″ W
12th St NE
Port Gardner
gwo
41st
o B l vd
15th
E
Dr
10th
St
Pl N
a mb
529
S n oh o
d an sl
Do
W
l te ki
Smith Island
S te
51st Ave SE
od D r
Inferred AD 900 to 930 tsunami deposit
38th St NE
2
gwo
od D r
od D r
St
e
ve N E
l NE
on ou
m
h
3 8th
St
Pacific
5
Snohomish River delta
hP
Sl
r Te
a
Av
529
Do
(near Naval 6–8 Station Everett)
in
ug
Un i
Rd
2–6
40 t
side
34th St
0–2
s
5
25th
Ave
Inundation Depth (feet)
Ebey Island
29th St SE
2
S lo
EVERETT
Naval Station Everett
204
51st Ave SE
American Legion Memorial Park
12 t h
12th St SE
29th St SE
Pacific
n
4th St SE
St
oat
48° 03′ 03.35″ N 122° 07′ 51.55″ W
Sundown Rd
28th Pl
mi sh os
a
e r in
River
St
vd
22nd
Bl
St
ide
19th
Spencer Island
529
Ave
5
41st
St
25th
Naval Station Everett
gwo
gwo o B l vd
15th
M
Line Rd
r
204
Do
Do 47° 57′ 32.05″ N 122° 14′ 25.70″ W
l te
Ferry Baker Is.
52nd Ave NE
S o p e r H ill Rd
R
ugh
NE
R i ve
St
51st Ave SE
ki
Port Gardner
10th
12th St SE
2
m
12th St NE
St
E
Dr
St
4th St SE
529
34th St
38th St NE
EVERETT 25th
Pacific
e 5
12 t h
EVERETT
Naval Station Everett
Av
a mb
529
S n oh o
d an sl
S lo
PRIEST POINT S te
MARYSVILLE
529
Dr
l NE
Rd
St
Smith Island
Pl N
side
22nd
American Legion Memorial Park
3 8th
River
St
h
r
19th
Spencer Island
s
R i ve
St
Ferry Baker Is.
os
Rd
15th
R
n
Snohomish River delta
hP
on
28th Pl
Ebey Island
side
Rd
12th St NE
Port Gardner
10th
St
ug
Un i
NE
mi sh
River
r
side
R i ve
38th St NE
40 t
S o p e r H ill Rd
Dr
St
12 t h
a in
d an sl
ys
e
S lo
48° 02′ 57.80″ N 122° 14′ 37.15″ W
nn
Av
5
River
10th
s
oat
Su
n
American Legion Memorial Park
os
amb
529
S n oh o
bia Ave lum
R
Ebey Island
Line Rd
ve N E
Sundown Rd
PRIEST POINT
on
E
a
gh
mi sh
M
l NE
S te
28th Pl
S o p e r H ill Rd
Dr
Port Gardner
Smith Island
Pl N
NE
529
S n oh o
52nd Ave NE
e r in
ou
h
3 8th
ugh
Sl
ug
Snohomish River delta
hP
gh
S lo
Un i
ou
oat
gh
28th Pl
d an sl
40 t
Sl
a mb
ve N E
Sundown Rd
PRIEST POINT
ou
E
in e
48° 03′ 03.35″ N 122° 07′ 51.55″ W
Co
S te
Sl
Pl N
Line Rd
l NE
on
vd
hP
ar
bia Ave lum
Un i
Smith Island
r Te
M
Dr
Co
52nd Ave NE
S lo
Maximum Current
MARYSVILLE
529
Bl
vd
PRIEST POINT
ough
ide
Bl
40 t
3 8th
Sl
Dr
ve N E
Sundown Rd
Snohomish River delta
529
48° 02′ 57.80″ N 122° 14′ 37.15″ W
48° 03′ 03.35″ N 122° 07′ 51.55″ W
ys
ide
a
bia Ave lum
M
e r in
MARYSVILLE
nn
ys
h lo u g Co
Dr
48° 02′ 57.80″ N 122° 14′ 37.15″ W
nn
S
48° 03′ 03.35″ N 122° 07′ 51.55″ W
Su
MARYSVILLE
529
Su
48° 02′ 57.80″ N 122° 14′ 37.15″ W
Modeled Inundation
Maximum Current
M
Modeled Inundation
W
Figure 4
1 kilometer
DISCUSSION One investigation has identified paleotsunami deposits in the Everett area. Bourgeois and Johnson (2001) identified numerous locations along sloughs of the Snohomish River delta that showed evidence of abrupt subsidence and an apparently continuous sheet of sand that overlies a soil dated to about AD 800–980 (Figs. 1 and 3), a range that completely contains the inferred age of the last Seattle fault earthquake (AD 900 to 930). These workers also found evidence for an older tsunami deposit (not shown on the figures) whose age is not well constrained. The tsunami model for Scenario A correlates well with all of the AD 900 to 930 tsunami deposit locations—the upstream extent of the model is approximately coincident with the most upstream tsunami deposits. However, because the sloughs are now protected by levees, the tsunami modeled here will behave differently from the AD 900 to 930 event even if the model perfectly matched the dynamics of that earthquake. Other potential tsunami sources for this area are not well enough understood to be included in this assessment. The southern Whidbey Island fault zone crosses Puget Sound a short distance south of Everett (Dragovich and others, 2002) but is not understood well enough to build a credible seismic scenario model. Tsunamis can also be caused by landslides, both subaqueous and subaerial. Historic landslide-induced tsunamis occurred multiple times in Lake Roosevelt, the impoundment behind Grand Coulee Dam (Lander and others, 1993), in the Tacoma tidal flats in 1894 (Kimball, 1897), the Tacoma Narrows in 1949 (González, 2003), and in the lower Columbia River in 1965 (Aberdeen Daily World, February 1, 1965). Shipman (2001) reported a landslide-induced tsunami generated from Camano Island that inundated a Native American village on Gedney (Hat) Island, probably early in the 19th century, as reconstructed from Native American oral history. Figure 7 shows the presumed landslide scar and the clearly vulnerable Gedney Island immediately to the south. While landslide sources clearly present at least a localized tsunami threat, modeling those tsunamis is beyond the scope of this effort.
Limitations of the Maps The largest source of uncertainty in these model results is the input earthquake event because the nature of the tsunami depends on the initial deformation. The earthquake scenarios used in this modeling were selected to honor the paleoseismic constraints, but the next Seattle fault earthquake may be substantially different from those that have been characterized. Sherrod and others (2000) show that a prior uplift event at Restoration Point (predating the AD 900 to 930 event) was smaller. Paleoseismic trenching of structures subsidiary to the Seattle fault—thought to be coseismic with the main fault trace (Nelson and Landslide on Camano Head Camano Island
Copyright © 1994–2014 Washington State Department of Ecology
Gedney (Hat) Island
Whidbey Island
Possession Sound
Imagery from 2011 Washington State NAIP
EVERETT
0
1
Figure 7. Historic landslide on Camano Head (inset, annotated) may have caused a tsunami at nearby Gedney (Hat) Island and inundated a Native American village.
2 miles
others, 2002)—indicates that there were at least two earthquakes in the 1500 years before the AD 900 to 930 event. These earthquakes, however, did not uplift prominent wavecut platforms similar to the one made by the AD 900 to 930 event, which suggests that not all earthquakes along the Seattle fault have the same amount of vertical or horizontal displacement. Kelsey and others (2008) suggested that at least some of the previous earthquakes may have been produced by bedding-plane slip on a fault-bend fold and were not located on the main Seattle fault at all. Another significant limitation is that the resolution of the modeling is no greater nor more accurate than the bathymetric and topographic data used—data cells are locally up to 50 m on a side. The models do not include the influences of changes in tides and are referenced to mean high water. The tide stage and tidal currents can amplify or reduce the impact of a tsunami on a specific community. At the Everett tide gage, the diurnal range (the difference in height between mean higher high water and mean lower low water) is about 11 ft (3.4 m) (accessed on August 8, 2014, at http://www.tidesandcurrents.noaa.gov). This means that, while the modeling can be a useful tool to guide evacuation planning, it is not of sufficient resolution to be useful for land-use planning.
ACKNOWLEDGMENTS This project was supported by NTHMP in cooperation with WAEMD. Information about NTHMP is available at http://nthmp.tsunami.gov/. During the study, NCTR maintained close communication with WAEMD and WADGER and, upon completion of the study, a suite of model-derived mapping products were delivered to both agencies in the form of electronic files and, where appropriate, hard copy representations. Reviews by Stephen Slaughter (WADGER) and John Schelling (WAEMD) were helpful.
REFERENCES Atwater, B. F., 1999, Radiocarbon dating of a Seattle earthquake to A.D. 900–930 [abstract]: Seismological Research Letters, v. 70, no. 2, p. 232. Atwater, B. F.; Moore, A. L., 1992, A tsunami about 1000 years ago in Puget Sound, Washington: Science, v. 258, no. 5088, p. 1614-1617. Blakely, R. J.; Wells, R. E.; Weaver, C. S., 1999, Puget Sound aeromagnetic maps and data: U.S. Geological Survey Open-File Report 99-514, version 1.0. [http://geopubs.wr.usgs.gov/ open-file/of99-514/] Blakely, R. J.; Wells, R. E.; Weaver, C. S.; Johnson, S. Y., 2002, Location, structure, and seismicity of the Seattle fault zone, Washington—Evidence from aeromagnetic anomalies, geologic mapping, and seismic-reflection data: Geological Society of America Bulletin, v. 114, no. 2, p. 169-177. Bourgeois, Joanne; Johnson, S. Y., 2001, Geologic evidence of earthquakes at the Snohomish delta, Washington, in the past 1200 yr: Geological Society of America Bulletin, v. 113, no. 4, p. 482-494. Brocher, T. M.; Blakely, R. J.; Wells, R. E., 2004, Interpretation of the Seattle uplift, Washington, as a passive-roof duplex: Seismological Society of America Bulletin, v. 94, no. 4, p. 1379-1401. Brocher, T. M.; Parsons, T. E.; Blakely, R. J.; Christensen, N. I.; Fisher, M. A.; Wells, R. E.; SHIPS Working Group, 2001, Upper crustal structure in Puget Lowland, Washington—Results from the 1998 Seismic Hazards Investigations in Puget Sound: Journal of Geophysical Research, v. 106, no. B7, p. 13,541-13,564. Bucknam, R. C.; Hemphill-Haley, Eileen; Leopold, E. B., 1992, Abrupt uplift within the past 1700 years at southern Puget Sound, Washington: Science, v. 258, no. 5088, p. 1611-1614. Bucknam, R. C.; Sherrod, B. L.; Elfendahl, G. W., 1999, A fault scarp of probable Holocene age in the Seattle fault zone, Bainbridge Island, Washington (abstract): Seismological Research Letters, v. 70, no. 2, p. 233. Daneš, Z. F.; Bonno, M.; Brau, J. E.; Gilham, W. D.; Hoffman, T. F.; Johansen, D.; Jones, M. H.; Malfait, Bruce; Masten, J.; Teague, G. O., 1965, Geophysical investigation of the southern Puget Sound area, Washington: Journal of Geophysical Research, v. 70, no. 22, p. 5573-5580. Dragovich, J. D.; Logan, R. L.; Schasse, H. W.; Walsh, T. J.; Lingley, W. S., Jr.; Norman, D. K.; Gerstel, W. J.; Lapen, T. J.; Schuster, J. E.; Meyers, K. D., 2002, Geologic map of Washington—Northwest quadrant: Washington Division of Geology and Earth Resources Geologic Map GM-50, 3 sheets, scale 1:250,000, with 72 p. text. [http://www.dnr.wa.gov/ Publications/ger_gm50_geol_map_nw_wa_250k.pdf] González, F. I., compiler, 2003, Puget Sound tsunami sources—2002 workshop report: NOAA/Pacific Marine Environmental Laboratory Contribution No. 2526, 36 p.
Gower, H. D., 1978, Tectonic map of the Puget Sound region, Washington, showing locations of faults, principal folds, and large-scale Quaternary deformation: U.S. Geological Survey Open-File Report 78-426, 22 p., 1 plate, scale 1:250,000. Jacoby, G. C.; Williams, P. L.; Buckley, B. M., 1992, Tree ring correlation between prehistoric landslides and abrupt tectonic events in Seattle, Washington: Science, v. 258, no. 5088, p. 1621-1623. Johnson, S. Y.; Dadisman, S. V.; Childs, J. R.; Stanley, W. D., 1999, Active tectonics of the Seattle fault and central Puget Sound, Washington—Implications for earthquake hazards: Geological Society of America Bulletin, v. 111, no. 7, p. 1042-1053, 1 plate. Kelsey, H. M.; Sherrod, B. L.; Nelson, A. R.; Brocher, T. M., 2008, Earthquakes generated from bedding plane-parallel reverse faults above an active wedge thrust, Seattle fault zone: Geological Society of America Bulletin, v. 120, no. 11-12, p. 1581-1597. Kimball, J. P., 1897, Physiographic geology of the Puget Sound basin (in 2 parts): American Geologist, v. 19, no. 4, p. 225-237 (part 1); v. 19, no. 5, p. 304-322 (part 2). Lander, J. F.; Lockridge, P. A.; Kozuch, M. J., 1993, Tsunamis affecting the west coast of the United States, 1806-1992: U.S. National Geophysical Data Center Key to Geophysical Records Documentation 29, 243 p. Lynett, P. J.; Borrero, Jose; Son, Sangyoung; Wilson, Rick; K. Miller, Kevin, 2014, Assessment of the tsunami-induced current hazard, Geophysical Research Letters, v. 41, n. 6, p. 2048–2055. doi:10.1002/2013GL058680. Nelson, A. R.; Johnson, S. Y.; Wells, R. E.; Pezzopane, S. K.; Kelsey, H. M.; Sherrod, B. L.; Bradley, L.-A.; Koehler, R. D., III; Bucknam, R. C.; Haugerud, R. A.; Laprade, W. T., 2002, Field and laboratory data from an earthquake history study of the Toe Jam Hill fault, Bainbridge Island, Washington: U.S. Geological Survey Open-File Report 02-60, 1 v., 2 plates. [http://pubs.usgs.gov/of/2002/ofr-02-0060/] Pratt, T. L.; Johnson, S. Y.; Potter, C. J.; Stephenson, W. J.; Finn, C. A., 1997, Seismic reflection images beneath Puget Sound, western Washington State—The Puget Lowland thrust sheet hypothesis: Journal of Geophysical Research, v. 102, no. B12, p. 27,469-27,489. Rogers, W. P., 1970, A geological and geophysical study of the central Puget Sound lowland: University of Washington Doctor of Philosophy thesis, 123 p., 9 plates. Sherrod, B. L.; Bucknam, R. C.; Leopold, E. B., 2000, Holocene relative sea level changes along the Seattle fault at Restoration Point, Washington: Quaternary Research, v. 54, no. 3, p. 384-393. Shipman, Hugh, 2001, The fall of Camano Head—A Snohomish account of a large landslide and tsunami in Possession Sound during the early 1800s: TsuInfo Alert, v. 3, no. 6, p. 13-14. [http://www.dnr.wa.gov/Publications/ger_tsuinfo_2001_v3_no6.pdf] Stewart, Mark, editor, 2005, Scenario for a magnitude 6.7 earthquake on the Seattle Fault: Earthquake Engineering Research Institute and Washington Military Department Emergency Management Division, 162 p. ten Brink, U. S.; Molzer, P. C.; Fisher, M. A.; Blakely, R. J.; Bucknam, R. C.; Parsons, T. E.; Crosson, R. S.; Creager, K. C., 2002, Subsurface geometry and evolution of the Seattle fault zone and the Seattle basin, Washington: Seismological Society of America Bulletin, v. 92, no. 5, p. 1737-1753. ten Brink, U. S.; Song, Jianli; Bucknam, R. C., 2006, Rupture models for the A.D. 900–930 Seattle fault earthquake from uplifted shorelines: Geology, v. 34, no. 7, p. 585-588. Titov, V. V.; González, F. I., 1997, Implementation and testing of the Method of Splitting Tsunami (MOST) model: NOAA Technical Memorandum ERL PMEL-112, PB98-122773, 11 p. Titov, V. V.; González, F. I.; Mofjeld, H. O.; Venturato, A. J., 2003, NOAA TIME Seattle tsunami mapping project—Procedures, data sources, and products: NOAA Technical Memorandum OAR PMEL-124, 21 p. Titov, V. V.; Synolakis, C. E., 1998, Numerical modeling of tidal wave run up: Journal of Waterway, Port, Coastal and Ocean Engineering, v. 124, n. 4, p. 157–171. Vancouver, George, 1798, repr. 1992, A voyage of discovery to the north Pacific Ocean, and round the world; in which the coast of north-west American has been carefully examined and accurately surveyed—Undertaken by His Majesty's command, principally with a view to ascertain the existence of any navigable communication between the north Pacific and north Atlantic Oceans; and performed in the years 1790, 1791, 1792, 1793, 1794, and 1795: G. G. and J. Robinson [London], 3 v. Venturato, A. J.; Arcas, Diego; Titov, V. V.; Mofjeld, H. O.; Chamberlin, C. C.; González, F. I., 2007, Tacoma, Washington, tsunami hazard mapping project— Modeling tsunami inundation from Tacoma and Seattle fault earthquakes: National Oceanic and Atmospheric Administration, Pacific Marine Environmental Laboratory Technical Memorandum OAR-PMEL-132, 23 p. Walsh, T. J.; Arcas, Diego; Venturato, A. J.; Titov, V. V.; Mofjeld, H. O.; Chamberlin, C. C.; González, F. I., 2009, Tsunami hazard map of Tacoma, Washington—Model results for Seattle fault and Tacoma fault earthquake tsunamis: Washington Division of Geology and Earth Resources Open File Report 2009-9, 1 sheet, scale 1:24,000. [http://www.dnr.wa.gov/ publications/ger_ofr2009-9_tsunami_hazard_tacoma.pdf]
Walsh, T. J.; Caruthers, C. G.; Heinitz, A. C.; Myers, E. P., III; Baptista, A. M.; Erdakos, G. B.; Kamphaus, R. A., 2000, Tsunami hazard map of the southern Washington coast—Modeled tsunami inundation from a Cascadia subduction zone earthquake: Washington Division of Geology and Earth Resources Geologic Map GM-49, 1 sheet, scale 1:100,000, with 12 p. text. [http://www.dnr.wa.gov/publications/ ger_gm49_tsunami_hazard_southern_coast.zip] Walsh, T. J.; Myers, E. P., III; Baptista, A. M., 2002a, Tsunami inundation map of the Port Angeles, Washington area: Washington Division of Geology and Earth Resources Open File Report 2002-1, 1 sheet, scale 1:24,000. [http://www.dnr.wa.gov/publications/ger_ofr2002-1_ tsunami_hazard_portangeles.pdf] Walsh, T. J.; Myers, E. P., III; Baptista, A. M., 2002b, Tsunami inundation map of the Port Townsend, Washington area: Washington Division of Geology and Earth Resources Open File Report 2002-2, 1 sheet, scale 1:24,000. [http://www.dnr.wa.gov/publications/ ger_ofr2002-2_tsunami_hazard_porttownsend.pdf] Walsh, T. J.; Myers, E. P., III; Baptista, A. M., 2003a, Tsunami inundation map of the Neah Bay, Washington, area: Washington Division of Geology and Earth Resources Open File Report 2003-2, 1 sheet, scale 1:24,000. [http://www.dnr.wa.gov/publications/ger_ofr2003-2_tsunami_ hazard_neahbay.pdf] Walsh, T. J.; Myers, E. P., III; Baptista, A. M., 2003b, Tsunami inundation map of the Quileute, Washington, area: Washington Division of Geology and Earth Resources Open File Report 2003-1, 1 sheet, scale 1:24,000. [http://www.dnr.wa.gov/publications/ger_ofr2003-1_tsunami_ hazard_quileute.pdf] Walsh, T. J.; Titov, V. V.; Venturato, A. J.; Mofjeld, H. O.; González, F. I., 2003c, Tsunami hazard map of the Elliott Bay area, Seattle, Washington—Modeled tsunami inundation from a Seattle fault earthquake: Washington Division of Geology and Earth Resources Open File Report 2003-14, 1 sheet, scale 1:50,000. [http://www.dnr.wa.gov/publications/ger_ofr2003-14_ tsunami_hazard_elliottbay.pdf] Walsh, T. J.; Titov, V. V.; Venturato, A. J.; Mofjeld, H. O.; González, F. I., 2004, Tsunami hazard map of the Bellingham area, Washington—Modeled tsunami inundation from a Cascadia subduction zone earthquake: Washington Division of Geology and Earth Resources Open File Report 2004-15, 1 sheet, scale 1:50,000. [http://www.dnr.wa.gov/publications/ger_ofr2004-15_ tsunami_hazard_bellingham.pdf] Walsh, T. J.; Titov, V. V.; Venturato, A. J.; Mofjeld, H. O.; González, F. I., 2005, Tsunami hazard map of the Anacortes–Whidbey Island area, Washington—Modeled tsunami inundation from a Cascadia subduction zone earthquake: Washington Division of Geology and Earth Resources Open File Report 2005-1, 1 sheet, scale 1:62,500. [http://www.dnr.wa.gov/ publications/ger_ofr2005-1_tsunami_hazard_anacortes_whidbey.pdf]
Suggested citation: Walsh, T. J.; Arcas, Diego; Titov, V. V.; Chamberlin, C. C., 2014, Tsunami hazard map of Everett, Washington: model results for magnitude 7.3 and 6.7 Seattle fault earthquake tsunamis: Washington Division of Geology and Earth Resources Open File Report 2014-03, 1 sheet, scale 1:32,000. Disclaimer: This product is provided ‘as is’ without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular use. The Washington Department of Natural Resources and the authors of this product will not be liable to the user of this product for any activity involving the product with respect to the following: (a) lost profits, lost savings, or any other consequential damages; (b) fitness of the product for a particular purpose; or (c) use of the product or results obtained from use of the product. This product is considered to be exempt from the Geologist Licensing Act [RCW 18.220.190 (4)] because it is geological research conducted by the State of Washington, Department of Natural Resources, Division of Geology and Earth Resources.
Base map from 2011 Snohomish County NAIP color 3-foot-resolution aerial photos HARN State Plane coordinate system, Washington South FIPS 4602 North American Datum of 1983 Shaded relief generated from U.S. Geological Survery 10-meter digital elevation model Digital cartography by Anne C. Olson Editing and production by Alexander N. Steely and Jaretta M. Roloff
© 2014 Washington Division of Geology and Earth Resources
