HomeMy WebLinkAboutA36 V6 Approved 2016 - Sect II - Natural Haz EJefferson County – City of Port Townsend All Hazard Mitigation Plan (Rev. 2016)
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EARTHQUAKES1
Definition
An earthquake is ground shaking caused primarily by an abrupt shift along a fracture in the earth, called a
fault. The earth’s crust is divided into eight major pieces (or plates) and many minor plates. These plates are constantly moving, very slowly, over the surface of the globe. As these plates move, stresses are built up in areas where the plates come into contact with each other. Within seconds, an earthquake releases stresses
that have slowly accumulated within the rock, in some instances over hundreds of years. Sometimes the release occurs near the surface, and sometimes it comes from deeper faults. Although. earthquakes are caused mostly by rupture of geological faults, they can also by other events such as volcanic activity, landslides, mine blasts, and nuclear tests. An earthquake's point of initial rupture is called its focus or hypocenter. The epicenter is the point at ground level directly above the hypocenter2.
“The severity of an earthquake is described by both magnitude and intensity. These two frequently confused
terms refer to different, but related, expressions. Magnitude, usually expressed as an Arabic numeral characterizes the size of an earthquake by measuring indirectly the energy released. By contrast, intensity indicates the local effects and potential for damage produced by an earthquake on the Earth's surface as it
affects humans, animals, structures, and natural objects such as bodies of water. Intensities are usually expressed in Roman numerals, and represent the severity of the shaking resulting from an earthquake. Ideally, any given earthquake can be described by only one magnitude, but many intensities since the earthquake effects vary with circumstances such as distance from the epicenter and local soil conditions3.” Charles Richter, the creator of the Richter magnitude scale, distinguished intensity and magnitude as follows: "I like to use the analogy with radio transmissions. … Magnitude can be compared to the power output in kilowatts of a broadcasting station. Local intensity on the Mercalli scale is then comparable to the signal
strength on a receiver at a given locality; in effect, the quality of the signal. Intensity, like signal strength, will generally fall off with distance from the source, although it also depends on the local conditions and the pathway from the source to the point."4
IMPACTS & EFFECTS
Loss of life
Loss of property
Injuries resulting in long term disabilities
Loss of jobs due to damaged
transportation
Disruption of the local
economy and government Disruption of water and food
lifelines
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Figure EQ-1 - Earthquake Measurement Systems
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History of Earthquakes affecting Jefferson County & the Puget Sound Region
Figure EQ-2 Large Earthquakes in the Northwest2
Washington State, especially the Puget Sound basin, has a history of frequent earthquakes. More than 1,000 earthquakes are recorded in the
state annually. Large earthquakes in 1949, 1965 and 2001 caused over $1 billion in damages throughout Puget Sound. The most recent large earthquake, the “Nisqually Earthquake” on February 28, 2001, was a 6.8 magnitude earthquake located 17.6 kilometers northeast of Olympia. All of the state, and the Puget Sound Basin area in particular, have a history of frequent earthquake
activity.
The 2001 Nisqually earthquake (“The Ash Wednesday earthquake") occurred at 10:54:32 local time on
February 28. It had a moment magnitude of 6.8 and a maximum Mercalli intensity of VIII (Severe). The epicenter was in the southern Puget Sound, northeast of Olympia, but the shock was felt in Oregon, Canada, eastern Washington, and Idaho. This was one of several large earthquakes that occurred in the Puget sound
region in the prior 52 years and caused property damage valued at between one and four billion dollars. One person died of a heart attack and several hundred were injured.5
All of East Jefferson County jurisdictions participating in the Hazard Mitigation Plan felt the shaking, and a few incurred substantial damage. The Port Ludlow Main Fire Station and Headquarters building had a wall crack that compromised the building. Fortunately, the firefighters were out on a call at the time, so no one
was hurt. A replacement building was estimated at two million dollars6.
Source: The [Port Ludlow] Village Voice, April 1, 2001
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The most infamous large earthquake to affect the area is the “Cascadia” earthquake that occurred at 21:00 on January 26, 1700. Its magnitude is estimated at between 8.7 and 9.2. At the time, there was no significant
population living in multi-story houses and working in concrete and steel cities, as there are now, but there was a thriving native culture that has handed down stories of the event. Table EQ-1 presents some of the native stories and their characteristics that helped to date the Cascadia Earthquake of 1700.
Table EQ-1 - Dating the 1700 Cascadia Earthquake from Native Stories7
Damaging levels of shaking have occurred over much of the state since records started being kept in 1790. In addition, geologic evidence also indicates that large, prehistoric earthquakes have occurred in areas prior to the beginning of record keeping.
Recorded damage sustained to date in Jefferson County has been relatively minor and has been restricted to some incidence of cracked foundations, walls, and pictures falling off of the wall. Recent
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exploration indicates that a prehistoric, sunken forest has been identified off Point Wilson on the line of the South Whidbey Fault. Geologic studies of faults adjacent to the county boundaries suggest that the
potential for serious earthquake damage is very real for the county. Table EQ-2 provides a list of some of the most significant earthquakes Washington has felt, but it is very easy to create a much longer list using the tools at the Pacific Northwest Seismic Network website8,9.
Table EQ-2 Cascadia Historic Earthquakes10,11
Date Time (PST)
Latitude/ Longitude
Depth (Km)
Mag
Location January 26, 1700 2100 9.0+ Cascadia Subduction Zone
May 4, 1834 2008 Felt in Port Townsend
April 2, 1859 0230 47000’ 123000’ Felt in Olympia
December 14, 1872 2140 48o48' 121o24' shallow 7.4 North Cascades
December 12, 1880 2040 47o30' 122o30' 5.5 Puget Sound
April 30, 1882 2248 47o00' 123o00' deep 6.0 Olympia area
November 29, 1891 1521 48o00' 123o30' 5.0 Puget Sound
March 6, 1893 1703 45o54' 119o24' shallow 4.9 Southeast Washington
January 3, 1896 2215 48o30' 122o48' 5.7 Puget Sound
March 16, 1904 2020 47o48' 123o00' 5.3 Olympics eastside
January 11, 1909 1549 48o42' 122o48' deep 6.0 Puget Sound
August 18, 1915 0605 48o30' 121o24' 5.6 North Cascades
January 23, 1920 2309 48o36' 123o00' 5.5 Puget Sound
July 17, 1932 2201 47o45' 121o50' shallow 5.2 Central Cascades
July 15, 1936 2308 46o00' 118o18' shallow 5.7 Southeast Washington
November 12, 1939 2346 47o24' 122o36' deep 5.7 Puget Sound
April 29, 1945 1216 47o24' 121o42' 5.5 Central Cascades
February 14, 1946 1914 47o18' 122o54' 40 6.3 Puget Sound
April 13, 1949 1155 47o06' 122o42' 54 7.1 Puget Sound
August 5, 1959 1944 47o48' 120o00' 35 Northwest Cascades
April 29, 1965 0728 47o24' 122o24 63 6.5 Puget Sound
February 13, 1981 2209 46o21' 122o14' 7 5.5 South Cascades
April 13, 1990 2133 48o51' 122o36' 5 5.0 Deming
January 28, 1995 1911 47o23' 122o21' 16 5.0 17.6 km NNE of Tacoma
May 2, 1996 2104 47o46' 121o57' 7 5.3 10.2 km ENE of Duvall
June 23, 1997 1113 47o36' 122o34' 7.4 4.9 5.5 km NE of Bremerton
July 2, 1999 1743 47o05' 123o28' 41 5.1 8.2 km N of Satsop
February 28, 2001 1054 47o 09’ 122o 52.4 52.4 6.8 17.6 km NE of Olympia
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Hazard Identification and Vulnerability Assessment
In Western Washington, the primary tectonic plates of interest are the Juan de Fuca and North American plates. The Juan de Fuca plate moves northeastward with respect to the North American plate at a rate of about 4 cm per year. The boundary where these two plates converge, the Cascadia Subduction Zone, lies approximately 50 miles offshore and extends from the middle of Vancouver Island in British Columbia to northern California. As it collides with North America, the Juan de Fuca
plate slides (or subducts) beneath the continent and sinks into the earth’s mantle. Jefferson County is vulnerable to the results of this continual movement of the earth’s tectonic plates.
Earthquake Hazards in Washington and Oregon
http://www.eqe.com/revamp/wash/index.html Pacific Northwest Seismograph Network
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The collision of the Juan de Fuca and North American plates produces three types of earthquakes, which
are designated by their location and origin. 1. Cascadia Subduction - “Great earthquakes”: The first type occurs along the Cascadia subduction fault, as a direct result of the convergence of these two plates. Although no large
earthquakes have occurred along the offshore Cascadia Subduction Zone since historic records started to be kept, similar subduction zones worldwide do produce “great” earthquakes—magnitude 8 or larger. A subduction earthquake would be centered off the
coast of Washington or Oregon where the plates converge. Such earthquakes typically have a minute or more of strong ground shaking and are quickly followed by damaging tsunamis and numerous large aftershocks. Subduction zone earthquakes have left compelling evidence from years past. These earthquakes were of enormous magnitude (8 to 9+) and recurred approximately every 550 years. The recurrence interval, however, has apparently been irregular, with the interval between earthquakes being as short as 100 years and as long as 1,100 years.
2. Juan de Fuca Plate - “Deep earthquakes”: The second type of earthquake occurs
within the Juan de Fuca plate as it sinks into the mantle. These are primarily deep earthquakes, approximately 25-100 kilometers in depth. Due to their depth, aftershocks are typically not felt in association with these earthquakes. The strongest of these recorded were the 1949 Olympia and the 1965 Sea-Tac earthquakes. Approximate “recurrence intervals” for intraplate earthquakes of various magnitude were estimated to be 35 years for magnitude 6.5 and 100 years for magnitude 7. Since 1870, there have been 7 earthquakes in the Puget
Sound basin of magnitudes of 6.0 or larger. Generally, these earthquakes last between 20 – 60 seconds.
3. North American Plate – “Shallow earthquakes”: The third type is an incident of
shallow earthquakes that occur within the North American plate. Conventional theory indicates that they occur when stress is transmitted from the Cascadia subduction fault into the interior of the North American plate. This type of earthquake has occurred throughout
Washington and most parts of Oregon. These earthquakes are primarily shallow with depths of 30 kilometers or less and generally have the magnitude of 5 to 5.5, however the largest recorded earthquake in Washington history was a 7.4 in 1872 and was thought to be shallow.
The majority of earthquakes that occur in the Pacific Northwest region are of the shallow kind occurring in the North America plate. The 1872 North Cascades earthquake, the 1945 earthquake near North Bend,
and the 1981 earthquake on the St. Helens seismic zone were all of this type. New evidence of a fault running east-west through south Seattle (the Seattle Fault) suggests that a major earthquake having a magnitude of 7 or greater affected the Seattle area about 1,000 years ago. Recent studies have found geologic evidence for large shallow earthquakes along the Seattle Fault 1,100 years ago within the central Puget Sound Basin. Massive block landslides into Lake Washington, marsh
subsidence and tsunami deposits at West Point in Seattle, tsunami deposits at Cultus Bay on Whidbey Island, and large rock avalanches on the southeastern Olympic Peninsula have all been dated to approximately 1,100 years ago.
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Evidence of a fault that runs east-west through Admiralty Inlet (the South Whidbey Island Fault) suggests that a major earthquake
affected the Port Townsend/Jefferson County area hundreds of years ago. Two “new” faults were recently discovered running north-
south from Whidbey to Vashon Island and possibly as far as Tacoma have the capacity to unleash earthquakes with magnitudes
greater than 7.2. The principal ways that earthquakes cause damage are by:
• strong ground shaking
• landslides,
• liquefaction,
• subsidence,
• tsunamis (seismic ocean waves),
• and seiches (rhythmic movements of
inland bodies of water). The actual movement of the ground in an earthquake is seldom the direct cause of injury or death.
Most casualties result from falling materials. Severe earthquakes usually disrupt utilities including: power, telephone, gas, sewer, solid waste, and water. Disruption of utilities for a lengthy period of time would have an untold effect on the economics of the county. The effects of an earthquake in Jefferson County are hard to define because of the many unpredictable variables involved. Soil liquefaction occurs when water saturated sands, silts, or gravels are shaken so violently that the
grains rearrange and the sediment loses strength, begins to flow out as sand boils or cause lateral spreading of overlying layers. Liquefaction causes loss of bearing strength under foundations or roadways, can trigger landslides, and can float low-density structures, such as partially empty fuel tanks, furnaces, and pilings. Liquefaction commonly causes ground failures such as ground cracking or lateral spreading above liquefied layers. Lateral spreads are spreads are landslides that can occur on very shallow slopes.
The time of the earthquake has a large impact on the potential for human casualties. The potential for casualties is greatest during the heaviest hours of traffic and when people are concentrated in schools and business areas. Typically, the twelve-hour period from six o’clock in the morning to six o’clock in the
evening has the greatest potential for human casualties. Site conditions and the types of soils or rock also affect the amount of shaking and the potential for damage. Solid rock or bedrock does not increase the shaking. Soft materials, however, such as mud, artificial fill and layers of sand and clay will make the consequences of ground shaking much worse. Jefferson County, particularly in the Port Townsend area that also has the highest concentration of people, has many
areas of sand and clay soil. These soil materials serve to increase or amplify the effects of an earthquake. Steep slopes may experience landslides. Floodplains and areas of artificial fill will be prone to liquefaction. This may result in
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pockets of local areas experiencing severe damage especially where the ground fails under buildings, water mains, pipelines or bridges. Building materials will greatly affect the impact of an earthquake on a structure. Unreinforced masonry structures, of which there are several in Port Townsend, are the most vulnerable while wood frame
structures typically perform well in earthquakes. Additionally, individual buildings have different natural frequencies of vibration that depend on their height and structural design. Amplification of frequencies may affect some buildings more than others. Strong shaking is a hazard both near the epicenter of an
earthquake and in areas where amplification occurs.
The effects of an earthquake could also vary widely by the buildings and infrastructure first damaged.
Damage to buildings that house emergency services such as fire stations and hospitals could lessen emergency response capabilities. Damage to roads, fallen trees, and failed bridges can also impair the delivery of emergency services. The majority of the county’s bridges were built prior to 1960 when engineering incorporated improved building practices in the event of an earthquake.
Earthquakes remain as one of the most significant hazard to people and property in Jefferson County. The Spaghetti Farm
While most people on the Olympic Peninsula should be aware of the Cascadia Subduction Zone because of proselytization by local emergency managers and neighborhood emergency groups. What many probably do
not realize is that they live in a veritable spaghetti farm of earthquake faults. What follows is a step-by-step walk around of the major named Quaternary faults that surround the Olympic Peninsula and have the potential to affect Jefferson County. Quaternary faults are those that have been recognized at the surface, which have moved in the past 1,600,000 years, a portion of the Quaternary epoch, and which are capable of a magnitude 6 or greater earthquake12. Table EQ-3 provides a table-of-contents for the next seven figures.
Table EQ-3 – Figures of Earthquake Faults affecting Jefferson County
Figure ID Name of Fault Map Description
EQ-3 Cascadia Subduction Zone13 A map of the subduction zone about 60 miles off the Washington’s Pacific coast.
EQ-4 Cascadia Subduction Zone with Coastal Quaternary Faults14
A map of the subduction zone with additional quaternary faults along Washington’s coast marked in white.
EQ-5 Copalis Beach Quaternary Fault15 Copalis Beach faults start in Grays Harbor county and extend upward just past the boundary with Jefferson County.
EQ-6 Cape Flattery Quaternary Fault16 Contains both land faults and a significant number of undersea faults at the mouth of the Strait of Juan de
Fuca.
EQ-7 Victoria Quaternary Fault (including Port Townsend, WA)17
This Quaternary Zone includes the Southern Whidbey Island fault, which is in the 3-mile wide channel between Port Townsend and Whidbey Island. It is capable of a magnitude 7.2+ tremor.
EQ-8 Seattle Quaternary Fault18
The Hood Canal fault zone can impact lower East Jefferson County, but most people worry about the Seattle Fault, which runs under the densely populated city.
EQ-9 Composite map of the Quaternary Faults that affect Jefferson County19
Any of these are capable of a 6.0+ earthquake on its
own. We have no way of knowing if or how many will be triggered by a Cascadia Subduction Zone event and / or if they will create significant aftershocks from different directions.
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Figure EQ-3 – The Cascadia Subduction Zone
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Figure EQ-4 – The Cascadia Subduction Zone with Coastal Faults (in white)
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Figure EQ-5 – The Copalis Beach Quaternary Fault Zone
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Figure EQ-6 – Cape Flattery Quaternary Fault Zone
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Figure EQ-7 – Victoria Quaternary Fault Zone (including Port Townsend)
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Figure EQ-8 – Seattle Quaternary Fault Zone
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Figure EQ-9 – Composite Map of Quaternary Faults affecting Jefferson County
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As one can see, there are a multitude of opportunities for earthquakes to occur in and around Jefferson County. Many do occur and are unnoticed because they are small and undistinguishable from the vibrations
inherent with a mechanized society. During the period from 1638 to 1928, just 2,500 earthquakes were reported in Oregon and Washington; during the period from 1928 to 1985, more than 18,500 events were reported20. Typically, each year over 1,000 earthquakes with a magnitude 1.0 or more are recorded in
Washington and Oregon21. There are two scenarios, however, that have the potential to severely damage Port Townsend and East Jefferson County: a 9.0+ magnitude rupture of the Cascadia Subduction Zone, and a 7.4+ rupture of the Southern Whidbey Island (SWI) Faults, just one and one half miles from Port Townsend. Because of its proximity, the Hazus simulations show that a Southern Whidbey Island event can do more damage to the urban centers of East Jefferson County than a Cascadia event, even though the Cascadia event could be 1000 times stronger. Scientists and emergency managers have combined two tools to model likely outcomes from the above occurrences, shakemaps and Hazus simulations. Caveat: These tools are for planning purposes only – and no plan survives its implementation. Earthquake Shakemap Scenarios describe the expected ground motions and effects of specific hypothetical
large earthquakes. In planning and coordinating emergency response, utilities, emergency responders, and other agencies are best served by conducting training exercises based on realistic earthquake situations, ones that they are most likely to face22. Shakemaps can be developed for both magnitude and intensity. Magnitude is the power of the earthquake, while intensity is the damage that is or can be done at some point distant. Remember the radio broadcast
analogy: magnitude is analogous to the output power of a radio transmitter, e.g. 50,000 watts; intensity is how well you can pick up the radio signal at some distance – except, here, we are talking about destruction caused by the earthquake. In the scenarios below, we have shakemaps for both magnitude and intensity. Hazus is a free tool from FEMA that estimates losses to specific buildings for earthquake and flood. Earthquake building losses were modeled at $165 million for a Southern Whidbey Island event of magnitude M7.4 and $104 million for a Cascadia M9.0 event. The losses reported are for building losses only and do not include losses for other infrastructure, such as the roads, ferry system, etc23. The City of Port Townsend and the unincorporated areas of the county have a large percentage of buildings
located in the moderate-high liquefaction zone. The City of Port Townsend will have a substantial impact if the Southern Whidbey Island event were to occur. The Hoh Tribe will experience the greatest impact from a Cascadia event24.
The Southern Whidbey Island Earthquake Scenario
Research has shown that the SWI faults are active and have generated at least four large earthquakes in the last 16,000 years25. Figure EQ-10 is a “shakemap scenario” representing a magnitude 7.4+ earthquake on the
Southern Whidbey Island (SWI) fault26. In the first SWI Scenario, a magnitude 7.4 earthquake occurs directly between Whidbey Island and Port
Townsend. Port Townsend will experience violent to extreme shaking.
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Figure EQ-10 – Southern Whidbey Island M7.4+ Earthquake Scenario
With the exception of the few public buildings that have been seismically retrofitted, Port Townsend’s Downtown Historic District consists mostly of multi-story unreinforced masonry structures built in the late
1800’s to early 1900’s. While buildings that have been seismically retrofitted may help the survivability of people inside, they are not likely to be functional because of the loss of utilities and infrastructure around them.
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Figure EQ-11 is a shakemap, modeled in 2015, using the Modified Mercalli (MM) scale to estimate damage
from a magnitude 7.4+ SWI earthquakes27. Note that the damage levels are marked in Roman numerals because
this shakemap is modeling the intensity of the earthquake.
Figure EQ-11 - Southern Whidbey Island M7.4+ Earthquake Scenario
Regardless of which map is used, it should be clear that Port Townsend is in real trouble if the SWI fault
generates a large earthquake. Not only will the downtown area be hit hard, but it is possible for a tsunami to be
generated right at the mouth of Port Townsend Bay, giving only minutes between the shaking and a tsunami
wave of unknown proportions.
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The Cascadia Subduction Zone (CSZ) Earthquake Scenario
A 1000-kilometer rupture of the Cascadia Subduction Zone is what people are most aware of and most concerned about. Most recently, attention to this possibility was heightened by an article titled “The Really Big One,” penned by Kathryn Schulz in The New Yorker (July 2015)28. It has also been written about in depth in the book, “Full Rip 9.0” by Sandi Doughton, Science Writer for the Seattle Times. This is a good thing in that by incentivizing people to prepare for “The Big One”, they are helping them get ready for a smaller but more devastating event from the SWI fault. This is not to say that the Cascadia event will not be as bad as people think. We simply are not yet
knowledgeable enough to make good predictions. The mantra at the Jefferson County EOC is “Please, Lord, not in my lifetime.” To try to better prepare for such a catastrophic event, FEMA and State and local agencies in the Cascade region of the country created a functional exercise, called Cascade Rising (CRX) to allow emergency management personnel to validate plans and readiness by performing their duties in a simulated operational environment
based on the Cascadia event29. It took two to three years of preparation for the multi-state, multi-jurisdiction, multi-agency exercise to be planned and then executed over a week-long period in June 2016. Part of the effort to build verisimilitude into the exercise was to collect data on vulnerable structures to create maps and simulated photos of destruction. This helps to understand the impact the Cascadia event will have on the region.
Source: Jefferson County Department of Emergency Management
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Figure EQ-12 is a shakemap scenario for a Cascadia event exceeding M9.030. It shows that East Jefferson
County, which is the economic engine for the area, will receive strong to very strong shaking, The concern with this is that the shaking will go on for many minutes. “A magnitude 9.0 earthquake can last for five minutes or longer, and the amount of energy released is 1,000 times greater than that of a 7.0. The most powerful quakes
could leave few if any masonry buildings standing, destroy bridges and toss objects into the air, according to the USGS.31 Figure EQ-12 - Cascadia M9.0+ Earthquake Scenario
The CSZ event shakemap (Figure EQ-13) shows that the majority of Jefferson County will experience
“very strong” to “severe” shaking intensity, with the West Jefferson County getting pockets of
“violent” shaking intensity32. U.S Hwy 101 can be expected to be busted up in multiple places. The
CRX showed that it would take a minimum of three hours for help to reach the West End, which has
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no significant emergency assets of its own. Air assets are likely to be the only way to get help to the
Hoh Tribe and to the pockets of tourist/survivors. During the tourist season, there can be 10,000+
tourists on the coast at any given time.
Figure EQ-13 - Cascadia M9.0+ Earthquake Shakemap
Hazus simulations, summarized in Table EQ-4, show that the destruction in Port Townsend can be
significantly higher for an SWI fault event than for an CSZ event of M9.0+. And while it is clear from
the caveats, that the damage estimates are understated, the relative levels of death and destruction make
sense. An CSZ generated earthquake will be somewhat attenuated by the time the shock waves hit East
Jefferson County, and the population will have about ninety minutes to get out of the way of any tsunami
generated. An SWI generated earthquake will be right on the City’s doorstep and give people about 10-
minutes to get off the Fort Worden beaches or out of the downtown area before any tsunami wave
created hits. Once again, at certain times of the year, particularly during festivals, Port Townsend’s
population can expand from 9,800 to 50,000 at sea level. It is plausible that people will just be picking
themselves off the ground when a tsunami wave hits.
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Table EQ-4 – Hazus Earthquake Results for Selected Scenarios33
The Bottom Line34
Jefferson County’s part of the world is unique in its geology, demographics and geography, and where we might fall in the line for help from state and/or federal agencies on the road to recovery. Jefferson County’s demographics stand out in terms of emergency response. Leading the other 38 counties in
the state for the 65 years+ age of its citizens, by 2020, it is estimated that 35.2 percent of Jefferson County’s population will be 65 and older. Despite lack of family-wage employment opportunities, the population increased by 15.1 percent from 2000 to 2010. There will likely be a higher percentage of special needs people
among survivors of a major quake than in more age-diversified areas. Jefferson County’s geography presents other challenges. The West end of Jefferson County, where the Hoh
Native American Reservation is located, is bordered by the Pacific Ocean. Clallam County is the border to the north; to the east, Admiralty Inlet and Hood Canal, and to the south, Grays Harbor and Mason counties. Port Townsend, the largest and only incorporated city in the county is on a peninsula. Access and egress to the peninsula by car is limited. The most common way to get here is via the Hood Canal Bridge. The second choice is by way of Highway 101. In the event of a disaster, both routes could easily be impacted for one reason or another. Potential damage to either or both of those routes emphasizes
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one of the disadvantages to the “Just-In-Time” delivery systems used by local retailers and businesses.
The ”Just-In-Time” inventory system has its advantages by eliminating the need for suppliers to have large warehouses to hold inventories. But there are also disadvantages to this system for the end-user. Of specific concern is the time of exceptional need for specific goods and supplies following a major disaster. Because of damaged roads or unavailable goods from suppliers, the shelves would remain empty and demands for specific products unmet.
In a study done by the Cascadia Region Earthquake Workgroup (2005), resupply issues for businesses in the Puget Sound area (to include not just grocery stores, but hospitals, pharmacies, emergency services, transportation related services, fuel, building materials and more) could quickly reach critical stages because of damages to previously used methods of delivery caused by a major disaster.
Getting supplies to the area by other means, should the need occur, would be at the top of the resource acquisition list for emergency management staff but the timeliness of acquiring those supplies would be dependent upon a number of things to include the overall impact of the disaster (how big an area was
damaged and to what extent); availability of supplies (resources going to the hardest hit areas with greater populations first) and securing alternate means of delivery of needed supplies to include manpower, food, water and medical supplies and whatever else might be critically needed to save lives).
Of note is the possibility there will be long term interruption of the supply chain on the peninsula after a M9.0 earthquake. Recovery could take years with some resources never recovering. “Contrary to what some believe is the case, an emergency management office—no matter the size of the community it serves—does not have a giant warehouse full of food, water and other supplies to distribute to residents,” said Bob Hamlin, Program Director of the Jefferson County Department of Emergency Management. “Our primary focuses are to provide public education and information, coordinate the response to a disaster, assessment and coordinate the delivery of state or federal assistance; support agency and jurisdictional partners, and run the Emergency Operations Center when it is activated for a countywide emergency,” he added.35
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Climate Change Not Applicable
Conclusion
Jefferson County is among the counties considered most at-risk and vulnerable to earthquake. Our evaluation
is that the County has a very high risk and a very high vulnerability. Figure EQ-15 - Counties Most Vulnerable to Earthquake36
Although scientists have tried for decades to predict earthquakes, no one has discovered a method that can be applied with regular success. For some areas with well-understood patterns of seismicity, it may be
possible to forecast decades-long time windows when large earthquakes are likely to occur. However, the Pacific Northwest has only been monitored for a couple of decades; not long enough to allow us to see what patterns, if any, exist here. Seismologists are still trying to understand what types of earthquakes are
possible here, and what kind of shaking we will experience from future earthquakes (depending on the earthquake location and size, and the site geology and topography).
Mitigation activities, including the following, should be instituted and maintained to lessen potential problems:
1. Examination, evaluation, and enforcement of effective building codes
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2. Geologically hazardous areas, as defined by the Growth Management Act, should be identified
and land use policies adopted to lessen risk.
3. Public information on what to do before, during, and after an earthquake should be provided to
citizens. Emphasis must be place on individual and family preparation for not just earthquake related disaster, but for all disasters. Since 2004, the City of Port Townsend has actively sought to seismically retrofit public buildings that are critical assets. City Hall, the police station, the city’s Historic Carnegie Library, City Water Distribution Center, tunnel lids and the City’s water tower have all been completed or are in the process of being seismically retrofitted. The city is also developing plans for a “Resiliency Center” to deal with the post-disaster recovery needs after a major event.
Earthquake hazards can be reduced by advance preparation; such as coordinating emergency communications and activities across jurisdictional lines, preparing personal emergency plans, and considering seismic hazards in land use plans, building codes, and planning for medical, utility, and emergency facilities. Education programs are currently in place to facilitate the development of individual, family and neighborhood preparedness.
Jefferson County – City of Port Townsend Hazard Mitigation Plan (Rev. 2016)
Vs. 6 155 September 2016
References – EARTHQUAKE
1. “Earthquake”, The Hazard Identification and Risk Assessment (THIRA), Jefferson County
Department of Emergency Management, 2011, pp. 17-23.
2. Earthquake, Wikipedia, Accessed August 27, 2016. Available at:
https://en.wikipedia.org/wiki/Earthquake
3. Seismic Scale, Wikipedia, Accessed August 27, 2016. Available at:
https://en.wikipedia.org/wiki/Seismic_scale
4. Ibid.
5. 2001 Nisqually Earthquake, Wikipedia, Accessed August 27, 2016. Available at:
https://en.wikipedia.org/wiki/2001_Nisqually_earthquake
6. Conversation with Chief Wayne Kier, 2004.
7. Dating the 1700 Cascadia Earthquake: Great Coastal Earthquakes in Native Stories, 2005, R. S. Ludwin, R. Dennis, D. Carver, A. D. McMillan, R. Losey, J. Clague, C. Jonientz-Trisler, J. Bowechop, J. Wray, and K. James, Seismological Research Letters, V. 76, No. 2
8. “Large Earthquakes in the Northwest”, Pacific Northwest Seismic Network, Accessed 2011.
http://www.geophys.washington.edu/SEIS/PNSN/INFO_GENERAL/ NQT/f13.html 9. Pacific Northwest Seismic Network, http://pnsn.org/
10. Cascadia State Significant Earthquakes, Cascadia Historic Earthquake Catalog 1793-1929, PNSN. Accessed August 2016. Available at: http://assets.pnsn.org/CASCAT2006/Index_1_24.html 11. “1928-1970 Washington and Oregon Earthquake information and Isoseismal Maps”, United States Earthquakes, U.S. Department of Commerce, Coast and Geodetic Survey 12. USGS FAQS, U. S. Geological Survey, Accessed August 2016. Available at: https://www2.usgs.gov/faq/categories/9838/3435 13. Cascadia Subduction Zone Map, by Ken Horvath, Jefferson County Department of Emergency Management, April 2014. 14. Cascadia Subduction Zone Map with Coastal Quaternary Faults, by Ken Horvath, Jefferson County Department of Emergency Management, April 2014.
15. Copalis Beach Quaternary Fault, U.S. Geological Survey, 2006, Quaternary fault and fold database
for the United States, accessed August 27, 2016, from USGS web site:
http//earthquakes.usgs.gov/regional/qfaults/.
16. Cape Flattery Quaternary Fault, U.S. Geological Survey, 2006, Quaternary fault and fold database
for the United States, accessed August 27, 2016, from USGS web site:
http//earthquakes.usgs.gov/regional/qfaults/.
17. Victoria Quaternary Fault, U.S. Geological Survey, 2006, Quaternary fault and fold database for the
United States, accessed August 27, 2016, from USGS web site:
http//earthquakes.usgs.gov/regional/qfaults/.
Jefferson County – City of Port Townsend Hazard Mitigation Plan (Rev. 2016)
Vs. 6 156 September 2016
18. Seattle Quaternary Fault, U.S. Geological Survey, 2006, Quaternary fault and fold database for the
United States, accessed August 27, 2016, from USGS web site:
http//earthquakes.usgs.gov/regional/qfaults/.
19. Composite Map of Quaternary Faults affecting Jefferson County, by Ken Horvath, Jefferson County Department of Emergency Management, April 2014. 20. NGDC Earthquake Intensity Database, Pacific Northwest Seismic Network, Accessed August 2016.
Available at: http://assets.pnsn.org/HIST_CAT/isoseismals.html
21. Frequently Asked Questions, PNSN Outreach, Accessed August 2016. Available at: http://www.pnsn.org/outreach/faq 22. Scenario Shakemaps, Earthquake Hazards Program, USGS, Accessed August 2016, Available at: http://earthquake.usgs.gov/hazards/products/scenario/
23. “Risk Report for Jefferson County, including the City of Port Townsend and the Hoh Tribe”, FEMA, January 2016, p.1 24. Ibid. 25. Ibid. 9.
26. Shakemap usSwif7.4_se, Earthquake Hazards Program, USGS, Accessed August 2016. Available at:
http://earthquake.usgs.gov/earthquakes/shakemap/global/shake/Swif7.4_se/
27. Ibid. 23,9.
28. Cascade Rising 2016, “CRZ Article 1”, By Bob Hamlin, Jefferson County Department of Emergency
Management, January 2016, p.1.
29. Ibid. 4.
30. Shakemap uscasc9.0_expanded_peak_se, Earthquake Hazards Program, USGS, Accessed August
2016. Available at:
http://earthquake.usgs.gov/earthquakes/shakemap/global/shake/casc9.0_expanded_peak_se/
31. Cascade Rising 2016, “CRZ Article 2”, By Bob Hamlin, Jefferson County Department of Emergency Management, February 2016, p.2.
32. Ibid. 23,10.
33. Ibid. 23,11. 34. Cascade Rising 2016, “CRZ Article 3”, By Bob Hamlin, Jefferson County Department of Emergency Management, February 2016, p.4. 35. Cascade Rising 2016, “CRZ Article 4”, By Bob Hamlin, Jefferson County Department of Emergency Management, February 2016, p.4. 36. “Earthquake Hazard Profile”, Washington State Enhanced Mitigation Plan, Washington Military Department, Emergency Management Division, May 2013, Tab 5.4, p.33. Available at: http://mil.wa.gov/uploads/pdf/HAZ-MIT-PLAN/Earthquake_Hazard_Profile.pdf
Jefferson County – City of Port Townsend Hazard Mitigation Plan (Rev. 2016)
Vs. 6 157 September 2016
Tables - EARTHQUAKE
EQ-1 Cascadia Historic Earthquakes EQ-2 Cascadia Historic Earthquakes
EQ-3 Figures of Earthquake Faults affecting Jefferson County
EQ-4 Hazus Earthquake Results for Selected Scenario Earthquakes
Figures - EARTHQUAKE
EQ-1 Large Earthquakes in the Northwest EQ-2 Large Earthquakes in the Northwest EQ-3 Cascadia Subduction Zone EQ-4 Cascadia Subduction Zone with Coastal Faults (in white) EQ-5 Copalis Beach Quaternary Fault EQ-6 Cape Flattery Quaternary Fault EQ-7 Victoria Quaternary Fault (including Port Townsend) EQ-8 Seattle Quaternary Fault EQ-9 Composite Map of Quaternary Faults that affect Jefferson County EQ-10 Southern Whidbey Island M7.4+ Earthquake Scenario
EQ-11 Southern Whidbey Island M7.4+ Earthquake Shakemap
EQ-12 Cascadia M9.0+ Earthquake Scenario
EQ-13 Cascadia M9.0+ Earthquake Shakemap
EQ-14 Hazus Earthquake Results for Selected Scenarios
EQ-15 Counties Most At-Risk and Vulnerable to Earthquake
Jefferson County – City of Port Townsend All Hazard Mitigation Plan (Rev. 2016)
Vs. 6 158 September 2016
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