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's magnitude ("size" or strength) based on its seismic moment. It was defined in a 1979 pape ...

of 6.8 and a maximum

Mercalli intensity The Modified Mercalli intensity scale (MM, MMI, or MCS), developed from Giuseppe Mercalli's Mercalli intensity scale of 1902, is a seismic intensity scale used for measuring the intensity of shaking produced by an earthquake. It measures the eff ...

of VIII (''Severe''). The

epicenter The epicenter, epicentre () or epicentrum in seismology is the point on the Earth's surface directly above a hypocenter or focus, the point where an earthquake or an underground explosion originates. Surface damage Before the instrumental pe ...

was in the southern

Puget Sound Puget Sound ( ) is a sound of the Pacific Northwest, an inlet of the Pacific Ocean, and part of the Salish Sea. It is located along the northwestern coast of the U.S. state of Washington. It is a complex estuarine system of interconnected ma ...

, northeast of Olympia, but the shock was felt in

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

eastern Washington Eastern Washington is the region of the U.S. state of Washington located east of the Cascade Range. It contains the city of Spokane (the second largest city in the state), the Tri-Cities, the Columbia River and the Grand Coulee Dam, the Hanf ...

, and

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyomi ...

. 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 Juan de Fuca (10 June 1536, Cefalonia 23 July 1602, Cefalonia)Greek Consulate of Vancouver,Greek Pioneers: Juan de Fuca. was a Greek pilot who served PhilipII of Spain. He is best known for his claim to have explored the Strait of Aniánnow k ...

tectonic plate Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...

's subduction under the

North American Plate The North American Plate is a tectonic plate covering most of North America, Cuba, the Bahamas, extreme northeastern Asia, and parts of Iceland and the Azores. With an area of , it is the Earth's second largest tectonic plate, behind the Pacif ...

at 3.5 to 4.5 cm a year as part of the

Cascadia subduction zone The Cascadia subduction zone is a convergent plate boundary that stretches from northern Vancouver Island in Canada to Northern California in the United States. It is a very long, sloping subduction zone where the Explorer, Juan de Fuca, a ...

. Three types of earthquake are observed in the area: rare megathrust events, such as the

1700 Cascadia earthquake The 1700 Cascadia earthquake occurred along the Cascadia subduction zone on January 26, 1700, with an estimated moment magnitude of 8.7–9.2. The megathrust earthquake involved the Juan de Fuca Plate from mid-Vancouver Island, south along the P ...

, shallow events within the North American Plate and deeper intraslab events within the Juan de Fuca Plate as it sinks into the 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 April 29, 1965 (magnitude 6.7, depth ), and 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 fault In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tecton ...

ing 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

FEMA - 1433 - Photograph by Kevin Galvin taken on 03-04-2001 in Washington

Although there were no directly related deaths, local news outlets reported that there was one death from a

heart attack A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which ma ...

. About 400 people were injured. Most of the property damage occurred very near the epicenter or in unreinforced concrete or

masonry Masonry is the building of structures from individual units, which are often laid in and bound together by mortar; the term ''masonry'' can also refer to the units themselves. The common materials of masonry construction are bricks, building ...

buildings, such as those in the

First Hill First Hill is a neighborhood in Seattle, Washington, United States. It is named for the hill on which it is located, which in turn is so named for being the first hill encountered while traveling east from downtown Seattle toward Lake Washing ...

, Pioneer Square, and

SoDo Sodo ( am, ሶዶ) or Wolaita Sodo ( am, ወላይታ ሶዶ) or ( Wolaytatto: ''Wolayta Sodo Ambbaa'') is a city in south-central Ethiopia. The administrative center of the Wolaita Zone. It has a latitude and longitude of with an elevation bet ...

neighborhoods of

Seattle Seattle ( ) is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2020 population of 737,015, it is the largest city in both the state of Washington and the Pacific Northwest regio ...

. The Trinity Parish Church on First Hill was severely damaged. The

air traffic control Air traffic control (ATC) is a service provided by ground-based air traffic controllers who direct aircraft on the ground and through a given section of controlled airspace, and can provide advisory services to aircraft in non-controlled airs ...

tower at

Seattle–Tacoma International Airport Seattle–Tacoma International Airport , branded as SEA Airport and also referred to as Sea–Tac (), is the primary commercial airport serving the Seattle metropolitan area in the U.S. state of Washington. It is in the city of SeaTac, which ...

was heavily damaged; it has since been replaced with a more earthquake-resistant tower. The quake splintered a buttress under the dome of the capitol building in Olympia, but previous earthquake-resistance work prevented more serious harm to the building. Additionally, power outages affected downtown Seattle. The U.S. Military's Ft. Lewis and McChord Air Force Base received damage and there was very slight damage in Victoria, British Columbia. FEMA - 5079 - Photograph by FEMA News Photo taken on 04-18-2001 in Washington

FEMA - 5079 - Photograph by FEMA News Photo taken on 04-18-2001 in Washington

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 The Boeing Company () is an American multinational corporation that designs, manufactures, and sells airplanes, rotorcraft, rockets, satellites, telecommunications equipment, and missiles worldwide. The company also provides leasing and p ...

's factories in the 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 The Alaskan Way Viaduct ("the viaduct" for short) was an elevated freeway in Seattle, Washington, United States, that carried a section of State Route 99 (SR 99). The double-decked freeway ran north–south along the city's waterfront for ...

and 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 M_W 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 George Walker Bush (born July 6, 1946) is an American politician who served as the 43rd president of the United States from 2001 to 2009. A member of the Republican Party, Bush family, and son of the 41st president George H. W. Bush, he ...

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 In seismology, a hypocenter or hypocentre () is the point of origin of an earthquake or a subsurface nuclear explosion. A synonym is the focus of an earthquake. Earthquakes An earthquake's hypocenter is the position where the strain energy ...

was deep under the earth. This earthquake was a 6.8 moment magnitude that caused $2 billion damage while the

Northridge earthquake The 1994 Northridge earthquake was a moment 6.7 (), blind thrust earthquake that occurred on January 17, 1994, at 4:30:55 a.m. PST in the San Fernando Valley region of the City of Los Angeles. The quake had a duration of approximatel ...

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 Delta, this earthquake hit the southern end of Puget Sound causing damage to the ports of Seattle and Tacoma.Nisqually Basin Bibliography: Science, Resource Management, Land Use, and Public Policy
In the month following the earthquake, the

National Oceanic and Atmospheric Administration The National Oceanic and Atmospheric Administration (abbreviated as NOAA ) is an United States scientific and regulatory agency within the United States Department of Commerce that forecasts weather, monitors oceanic and atmospheric conditio ...

and the

USGS The United States Geological Survey (USGS), formerly simply known as the Geological Survey, is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its natural resources, a ...

assembled a team to map the

bathymetry Bathymetry (; ) is the study of underwater depth of ocean floors (''seabed topography''), lake floors, or river floors. In other words, bathymetry is the underwater equivalent to hypsometry or topography. The first recorded evidence of water ...

of the deltas near the epicenter. This revealed multiple submarine failures on the Puyallup and 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 The Billy Frank Jr. Nisqually National Wildlife Refuge is a wildlife preserve operated by the United States Fish and Wildlife Service on the Nisqually River Delta near Puget Sound in northeastern Thurston County, Washington and northwestern Pierc ...

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.

References

External links

M 6.8 - Puget Sound region, Washington
from the

15 years after the Nisqually Earthquake, King County prepares for "the big one"
–

King County, Washington King County is located in the U.S. state of Washington. The population was 2,269,675 in the 2020 census, making it the most populous county in Washington, and the 13th-most populous in the United States. The county seat is Seattle, also the ...

Special Coverage: Ash Wednesday Quake
– ''

Seattle Weekly The ''Seattle Weekly'' is an alternative biweekly distributed newspaper in Seattle, Washington, United States. It was founded by Darrell Oldham and David Brewster as ''The Weekly.'' Its first issue was published on March 31, 1976. The newspaper ...

'' * {{DEFAULTSORT:Nisqually 2001 natural disasters in the United States 2001 earthquakes 2001 Nisqually

Nisqually earthquake The 2001 Nisqually earthquake occurred at on February 28, 2001 and lasted nearly a minute. The intraslab earthquake had a moment magnitude of 6.8 and a maximum Mercalli intensity of VIII (''Severe''). The epicenter was in the southern Puget So ...