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The 2001 Nisqually earthquake occurred at on February 28, 2001 and lasted nearly a minute. The intraslab earthquake had a
moment magnitude The moment magnitude scale (MMS; denoted explicitly with or Mw, and generally implied with use of a single M for magnitude) is a measure of an earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surf ...
of 6.8 and a maximum Mercalli intensity of VIII (''Severe''). The
epicenter The epicenter, epicentre () or epicentrum in seismology Seismology (; from Ancient Greek σεισμός (''seismós'') meaning "Earthquake, earthquake" and -λογία (''-logía'') meaning "study of") is the scientific study of earthquakes ...

epicenter
was in the southern
Puget Sound Puget Sound () is a of the , an inlet of the , and part of the . It is located along the northwestern coast of the of . It is a complex system of interconnected marine waterways and basins, with one major and two minor connections to the ope ...
, northeast of
Olympia The name Olympia may refer to: Arts and media Film * ''Olympia'' (1938 film), by Leni Riefenstahl, documenting the Berlin-hosted Olympic Games * ''Olympia'' (1998 film), about a Mexican soap opera star who pursues a career as an athlete * ''Ol ...
, but the shock was felt in
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...

Oregon
,
British Columbia ( en, Splendour without diminishment) , image_map = British Columbia in Canada 2.svg , Label_map = yes , coordinates = , official_lang = None , Slogan = Beautiful British C ...

British Columbia
,
eastern Washington Eastern Washington is the region of the U.S. state In the United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primari ...
, and
Idaho Idaho () is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspaper in ...

Idaho
. This was the most recent of several large earthquakes that occurred in the Puget Sound region over a 52-year period and caused property damage valued at $1–4 billion. One person died of a heart attack and several hundred were injured.


Tectonic setting

The Puget Sound area is prone to deep earthquakes due to the
Juan de Fuca Ioannis Phokas ( el, Ἰωάννης Φωκᾶς), better known by the Spanish Spanish may refer to: * Items from or related to Spain: **Spaniards, a nation and ethnic group indigenous to Spain **Spanish language **Spanish cuisine Other place ...

Juan de Fuca
tectonic plate This is a list of tectonic plates on Earth's surface Earth is the third planet A planet is an astronomical body orbiting a star or Stellar evolution#Stellar remnants, stellar remnant that is massive enough to be Hydrostatic equilibri ...
's
subduction Subduction is a geological process in which the oceanic lithosphere A lithosphere ( grc, λίθος [] for "rocky", and [] for "sphere") is the rigid, outermost shell of a terrestrial planet, terrestrial-type planet or natural satellite. O ...

subduction
under the
North American Plate The North American Plate is a tectonic plate This is a list of tectonic plates on Earth's surface Earth is the third planet A planet is an astronomical body orbiting a star or Stellar evolution#Stellar remnants, stellar remnant th ...
at 3.5 to 4.5 cm a year as part of the
Cascadia subduction zone The Cascadia subduction zone is a convergent Convergent is an adjective for things that wikt:converge, converge. It is commonly used in mathematics and may refer to: *Convergent boundary, a type of plate tectonic boundary * Convergent (continue ...
. Three types of earthquake are observed in the area: rare megathrust events, such as the 1700 Cascadia earthquake, shallow events within the North American Plate and deeper intraslab events within the Juan de Fuca Plate as it sinks into the earth's mantle, mantle. The third type of earthquake is the one that has led to the greatest amount of damage. Significant intraslab earthquakes occurred in the same general region on 1965 Puget Sound earthquake, April 29, 1965 (magnitude 6.7, depth ), and 1949 Olympia earthquake, April 13, 1949 (magnitude 6.7, depth ).


Earthquake

The earthquake was an intraslab event within the Juan de Fuca Plate. It was a result of normal faulting within the descending slab, but it has not been possible to determine which of the two possible fault planes indicated by the focal mechanism is correct.


Damage

Although there were no directly related deaths, local news outlets reported that there was one death from a Myocardial infarction, heart attack. About 400 people were injured. Most of the property damage occurred very near the epicenter or in unreinforced concrete or masonry buildings, such as those in the First Hill, Seattle, First Hill, Pioneer Square, Seattle, Pioneer Square, and SoDo, Seattle, SoDo neighborhoods of Seattle. The Trinity Episcopal Parish Church (Seattle), Trinity Parish Church on First Hill was severely damaged. The air traffic control tower at Seattle–Tacoma International Airport was heavily damaged; it has since been replaced with a more earthquake-resistant tower. The quake splintered a buttress under the dome of the Washington State Capitol, capitol building in Olympia, but previous earthquake-resistance work prevented more serious harm to the building. Additionally, power outages affected downtown Seattle. The United States Armed Forces, U.S. Military's Joint Base Lewis–McChord, Ft. Lewis and McChord Air Force Base received damage and there was very slight damage in Victoria, British Columbia. Following the quake, many buildings and structures in the area were closed temporarily for inspection. This included several bridges, all state offices in Olympia, and Boeing's factories in the Seattle metropolitan area, Seattle area. Various schools in the state also closed for the day. The Fourth Avenue Bridge in downtown Olympia was heavily damaged and was later torn down and re-built. In Seattle, the Alaskan Way Viaduct and Alaskan Way Seawall, its seawall were damaged, forcing the viaduct to close for emergency repairs and ultimately factoring into the decision to replace the viaduct with the SR 99 Tunnel and an expanded Alaskan Way on the footprint of the old viaduct. The new tunnel is designed to withstand a 9.0 MW earthquake. Approximately $305 million of insured losses and a total of $2 billion worth of damage was caused in the state of Washington. The area was declared a natural disaster area by president George W. Bush and was therefore able to receive federal recovery assistance. The number of businesses in the heavily affected region was relatively small. At least 20% of businesses surrounding the heavily affected area took direct losses, while 2% had direct losses of over $10,000. None of these businesses received money for direct damage from federal aid or insurance. Many businesses did not receive any aid at all. Those that did receive aid had no help with indirect losses. Indirect losses varied from inventory or data corruption, disruption in the workplace, productivity, etc. Data and inventory losses were possibly the most damaging, especially for retail stores. Retail stores lost inventory as well as people's interest for a period of time after the quake. One of the vital elements to prevent damage and injury were well structured buildings. This can prevent the loss of life as well as inventory. Businesses that did not sustain very much damage also gained a sense of security that may be unreliable as the moment magnitude was high but the hypocenter was deep under the earth. This earthquake was a 6.8 moment magnitude that caused $2 billion damage while the 1994 Northridge earthquake, Northridge earthquake was a 6.7 moment magnitude, but caused more than $20 billion worth of damage as the hypocenter of the Northridge earthquake was much shallower and closer to the surface of the earth.


Ground effects

Named after the Nisqually River, Nisqually Delta, this earthquake hit the southern end of Puget Sound causing damage to the ports of Seattle and Tacoma, Washington, Tacoma.Nisqually Basin Bibliography: Science, Resource Management, Land Use, and Public Policy
In the month following the earthquake, the National Oceanic and Atmospheric Administration and the United States Geological Survey, USGS assembled a team to map the bathymetry of the deltas near the epicenter. This revealed multiple submarine failures on the Puyallup River, Puyallup and Duwamish River, Duwamish delta fronts. In other areas liquefaction, sand boils, landslides, and soil slumping occurred. Liquefaction was also determined to be a main contributor to increased stream flows. With multiple stream gauges collecting data before and after the earthquake there was a regular pattern of higher increased stream flow around areas where liquefaction occurred. Soil liquefaction was also observed at the Nisqually National Wildlife Refuge causing damage to the buildings within.


Response

A rapid response plan was developed a year later. The region realized how they avoided a potential extremely damaging catastrophe. Many businesses, organizations, hospitals, etc. were asked to sign a regional disaster plan. This would allow disaster relief teams to locate and aid places much faster than before. It would also be able to direct limited resources to places with greatest immediate need.


See also

*List of earthquakes in 2001 *List of earthquakes in the United States *List of earthquakes in Washington (state)


References


External links


M 6.8 - Puget Sound region, Washington
from the USGS
15 years after the Nisqually Earthquake, King County prepares for "the big one"
– King County, Washington
Special Coverage: Ash Wednesday Quake
– ''Seattle Weekly'' * {{DEFAULTSORT:Nisqually 2001 natural disasters in the United States 2001 earthquakes Earthquakes in Washington (state), 2001 Nisqually 2001 in Washington (state), Nisqually earthquake