![]() A stretch of Washington State Route 302 near Allyn, Washington, damaged after the earthquake | |
UTC time | 2001-02-28 18:54:32 |
---|---|
ISC event | 1780664 |
USGS-ANSS | ComCat |
Local date | February 28, 2001 |
Local time | 10:54:32 a.m. [1] |
Magnitude | 6.8 Mw [1] |
Depth | 57 km (35 mi) [1] |
Epicenter | 47°11′N122°40′W / 47.19°N 122.66°W [1] |
Type | Normal [2] |
Areas affected | Pacific Northwest |
Total damage | $1–4 billion [3] |
Max. intensity | MMI VIII (Severe) [4] |
Peak acceleration | 0.3 g [4] |
Tsunami | No |
Casualties | 1 dead (heart attack), 400 injured [3] |
The 2001 Nisqually earthquake occurred at 10:54:32 local time on February 28, 2001, and lasted nearly a minute. [5] 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 Sound, northeast of Olympia, but the shock was felt in Oregon, British Columbia, eastern Washington, and Idaho. [6] 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.
The Puget Sound area is prone to deep earthquakes due to the Juan de Fuca tectonic plate's subduction under the North American Plate at 3.5 to 4.5 cm a year [6] as part of the Cascadia subduction zone. 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 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 59 km (37 mi)), and April 13, 1949 (magnitude 6.7, depth 50 km (31 mi)). [7]
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. [7] [2]
Although there were no directly related deaths, local news outlets reported that there was one death from a heart attack. [8] About 400 people were injured. [8] Most of the property damage occurred very near the epicenter or in unreinforced concrete or masonry buildings, such as those in the First Hill, Pioneer Square, and SoDo neighborhoods of Seattle. The Trinity Parish Church on First Hill was severely damaged. [9] 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 capitol building in Olympia, but previous earthquake-resistance work prevented more serious harm to the building. [10] Additionally, power outages affected downtown Seattle. [11] The U.S. Military's Ft. Lewis and McChord Air Force Base received damage and there was very slight damage in Victoria, British Columbia. [12]
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 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. [13] [14] In Seattle, the Alaskan Way Viaduct 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. [15] The new tunnel is designed to withstand a 9.0 MW earthquake. [16]
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. [17] 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. [17]
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. [17] 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 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. [17] [18]
Named after the Nisqually Delta, this earthquake hit the southern end of Puget Sound causing damage to the ports of Seattle and Tacoma. [19] [8] In the month following the earthquake, the National Oceanic and Atmospheric Administration and the USGS assembled a team to map the bathymetry 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. [19] 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. [20] Soil liquefaction was also observed at the Nisqually National Wildlife Refuge causing damage to the buildings within. [21]
A rapid response plan was developed a year later. The region realized how they avoided a potential extremely damaging catastrophe. Many businesses, organizations, and hospitals 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. [6] [22]
Puget Sound is a sound on the northwestern coast of the U.S. state of Washington. It is a complex estuarine system of interconnected marine waterways and basins. A part of the Salish Sea, Puget Sound has one major and two minor connections to the Strait of Juan de Fuca, which in turn connects to the open Pacific Ocean. The major connection is Admiralty Inlet; the minor connections are Deception Pass and the Swinomish Channel.
An intraplate earthquake is an earthquake that occurs in the interior of a tectonic plate, in contrast to an interplate earthquake on the boundary of a tectonic plate. It is also called an intraslab earthquake, especially when occurring in a microplate.
The New Madrid Seismic Zone (NMSZ), sometimes called the New Madrid Fault Line, is a major seismic zone and a prolific source of intraplate earthquakes in the Southern and Midwestern United States, stretching to the southwest from New Madrid, Missouri.
The Seattle Fault is a zone of multiple shallow east–west thrust faults that cross the Puget Sound Lowland and through Seattle in the vicinity of Interstate Highway 90. The Seattle Fault was first recognized as a significant seismic hazard in 1992, when a set of reports showed that about 1,100 years ago it was the scene of a major earthquake of about magnitude 7 – an event that entered Native American oral traditions. Extensive research has since shown the Seattle Fault to be part of a regional system of faults.
The Cascadia subduction zone is a 960 km (600 mi) fault at a convergent plate boundary, about 110–160 km (70–100 mi) off the Pacific coast, that stretches from northern Vancouver Island in Canada to Northern California in the United States. It is capable of producing 9.0+ magnitude earthquakes and tsunamis that could reach 30 m (98 ft). The Oregon Department of Emergency Management estimates shaking would last 5–7 minutes along the coast, with strength and intensity decreasing further from the epicenter. It is a very long, sloping subduction zone where the Explorer, Juan de Fuca, and Gorda plates move to the east and slide below the much larger mostly continental North American Plate. The zone varies in width and lies offshore beginning near Cape Mendocino, Northern California, passing through Oregon and Washington, and terminating at about Vancouver Island in British Columbia.
The 1950 Assam–Tibet earthquake, also known as the Assam earthquake, occurred on 15 August and had a moment magnitude of 8.7. The epicentre was located in the Mishmi Hills. It is the strongest earthquake ever recorded on land and is tied with the 2012 Indian Ocean Earthquakes as the strongest Strike-slip earthquake to date.
The 1992 Landers earthquake occurred on Sunday, June 28 with an epicenter near the town of Landers, California, in San Bernardino County. The shock had a moment magnitude of 7.3 and a maximum Mercalli intensity of IX (Violent).
The 1993 Scotts Mills earthquake, also known as the "Spring break quake", occurred in the U.S. state of Oregon on March 25 at 5:34 AM Pacific Standard Time. With a moment magnitude of 5.6 and a maximum perceived intensity of VII on the Mercalli intensity scale, it was the largest earthquake in the Pacific Northwest since the Elk Lake and Goat Rocks earthquakes of 1981. Ground motion was widely felt in Oregon's Willamette Valley, the Portland metropolitan area, and as far north as the Puget Sound area near Seattle, Washington.
The 1949 Olympia earthquake occurred on April 13 at 11:55:44 local time with a moment magnitude of 6.7 and a maximum Mercalli Intensity of VIII (Severe). The shock was located in the area between Olympia and Tacoma, and was felt throughout the state, as well as parts of Oregon, British Columbia, Idaho, and Montana. It is the largest recorded earthquake to occur in the Puget Sound region of Washington. Eight people were killed, a minimum of 64 people were injured, and the total damage is estimated at $25 million.
The 1946 Vancouver Island earthquake struck Vancouver Island on the coast of British Columbia, Canada, on June 23 at 10:15 a.m. with a magnitude estimated at 7.0 Ms and 7.5 Mw. The main shock epicenter occurred in the Forbidden Plateau area northwest of Courtenay. While most of the large earthquakes in the Vancouver area occur at tectonic plate boundaries, the 1946 Vancouver Island earthquake was a crustal event. Shaking was felt from Portland, Oregon, to Prince Rupert, British Columbia. This is one of the most damaging earthquakes in the history of British Columbia, but damage was restricted because there were no heavily populated areas near the epicentre, where severe shaking occurred.
The 2003 Hokkaidō earthquake, scientifically named the 2003 Tokachi-Oki earthquake, occurred off the coast of Hokkaidō, Japan on 26 September at 04:50 local time. At a focal depth of 27 km (17 mi), this great undersea earthquake measured 8.3 on the moment magnitude scale, making it the most powerful earthquake of 2003, as well as one of the most intense earthquakes to hit Japan since modern record-keeping began in 1900.
The 1965 Puget Sound earthquake occurred at 08:28 AM PDT on April 29 within the Puget Sound region of Washington state. It had a magnitude of 6.7 on the moment magnitude scale and a maximum perceived intensity of VIII (Severe) on the Mercalli intensity scale. It caused the deaths of seven people and about $12.5–28 million in damage. There were no recorded aftershocks.
The Tacoma Fault, just north of the city of Tacoma, Washington, is an active east–west striking north dipping reverse fault with approximately 35 miles (56 km) of identified surface rupture. It is believed capable of generating earthquakes of at least magnitude Mw 7, and there is evidence of such a quake approximately 1,000 years ago, possibly the same earthquake documented on the Seattle Fault 24 miles (38 km) to the north.
The 1872 North Cascades earthquake occurred at 9:40 p.m. local time on December 14 in central Washington Territory. A maximum Mercalli intensity of VIII (Severe) was assessed for several locations, though less intense shaking was observed at many other locations in Washington, Oregon, and British Columbia. Some of these intermediate outlying areas reported V (Moderate) to VII shaking, but intensities as high as IV (Light) were reported as far distant as Idaho and Montana. Due to the remote location of the mainshock and a series of strong aftershocks, damage to structures was limited to a few cabins close to the areas of the highest intensity.
On November 30, 2018, at 8:29 a.m. AKST (17:29 UTC), a magnitude 7.1 earthquake hit Anchorage in South Central Alaska. The earthquake's epicenter was near Point Mackenzie, about 10 miles (16 km) north of Anchorage, and occurred at a depth of 29 miles (47 km). It was followed six minutes later by a magnitude 5.7 aftershock centered 2.5 miles (4.0 km) north-northwest of the municipality. The earthquake could be felt as far away as Fairbanks.
An earthquake measuring Mw 8.0 struck Peru and the surrounding areas on 26 May 2019 at 02:41 local time. It had a maximum perceived intensity of VII on the Modified Mercalli intensity scale in the towns of Yurimaguas and Lagunas. Two people died and a further 30 were injured. It was the strongest earthquake in 2019 by magnitude.
The 1988 Myanmar–India earthquake, also known as the Indo–Burma earthquake struck the Sagaing Region of Myanmar, about 30 kilometres (19 mi) from the border with India on 6 August at 7:06 am MMT with a moment magnitude (Mw ) of 7.3 or Richter magnitude (ML ) of 7.5. At least five people were killed, more than 30 were injured, and another 30 were missing as a result. Serious damage was reported in India and Bangladesh, while some minor damage occurred in Myanmar. The earthquake was reportedly felt in the Soviet Union.
The 1950 Calama earthquake occurred near the Argentina–Chile border with an epicenter near Calama, Chile in the Atacama Desert on December 9. The event had a hypocenter depth of 113.9 km, beneath the Caichinque volcanic complex. It measured magnitude Mw 8.2 on the moment magnitude scale, making it the largest intermediate depth earthquake ever recorded on Chilean soil. One person was killed and an unspecified number of people were injured in Calama.
The 1984 Cachar earthquake rattled much of Southern Assam on December 31, 1984, at 5:03 a.m. (UTC+5:30) with an epicenter 20 kilometers southwest of Lakhipur. The quake measured with a magnitude of 6.0 on the moment magnitude scale and an estimated intensity of VIII (Severe) on the Modified Mercalli intensity scale. About 20 people died and 100 others sustained mild to severe injuries.
The 1870 Charlevoix earthquake occurred on 20 October in the Canadian province of Quebec. It had a moment magnitude of 6.6 Mw and a Modified Mercalli intensity rating of X (Extreme). The town of Baie-Saint-Paul was seriously damaged by the event, with the loss of six lives. Effects from the earthquake were felt as far as Virginia and along the New England coast of the United States.