2002 Denali earthquake
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2002 Denali earthquake
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| Date | November 3, 2002 |
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| Magnitude | 7.9 Mw |
| Depth | 5 km |
| Epicenter | Denali National Park, Alaska |
| Countries or regions | United States |
| Casualties | No fatalities |
The 2002 Denali earthquake occurred at 22:12:41 UTC (1:12 PM Local Time) November 3, 2002, with an epicenter 66 km ESE of Denali National Park, Alaska, United States. This 7.9 Mw earthquake was the largest recorded in the interior of the United States for more than 150 years. The shock was the strongest ever recorded in the interior of Alaska.[1] There were no fatalities and only a few injuries due to the remote location.
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Earthquake damage
Minor damage was reported over a wide area but the only examples of severe damage were on highways that crossed the fault trace and areas that suffered liquefaction, e.g. Northway Airport.[2] Several bridges were damaged but none so severely that they were closed to traffic.
The Trans-Alaska Pipeline System crosses the rupture trace; the pipeline suffered some minor damage to supports during the earthquake. There was no oil spillage, as the pipeline at that location was designed to move laterally along beams to withstand major movement on the Denali Fault.[3] The pipeline was shut down for three days to allow for inspections but was then reopened.
Tectonic setting
The Denali-Totschunda fault is a major dextral (right lateral) strike-slip system, similar in scale to the San Andreas fault system.
In Alaska, moving from east to west, the plate interactions change from a transform boundary between Pacific and North American plates to a collision zone with a microplate, the Yakutat terrane, which is in the process of being accreted to the North American plate, to a destructive boundary along the line of the Aleutian islands. The Denali-Totschunda fault system is one of the structures that accommodate the accretion of the Yakutat terrane.
Earthquake characteristics
On October 23, 2002, there was a magnitude 6.7 earthquake located on the Denali fault. Because of its location close to the November 3 event and the fact that it preceded it by only 11 days, this earthquake is regarded as a foreshock that probably directly triggered the main shock.
The initial rupture on November 3 was on a thrust fault segment, the previously unknown Susitna Glacier thrust,[4][5] to the south of the Denali fault. The epicenter lies just 25 kilometers (16 mi) east of the October 23 foreshock. The rupture then jumped to the main Denali fault strand propagating for a further 220 km (137 mi) before jumping again onto the Totschunda fault and rupturing another 70 km (43 mi) of fault plane[5]. The total surface rupture was ca. 340 km (211 mi).
There is evidence of local supershear propagation inferred from ground motions.[6]
See also
References
- ^ Fuis, Gary S.; Wald, Lisa A. (February 5, 2003). "Fact Sheet 014-03: Rupture in South-Central Alaska—The Denali Fault Earthquake of 2002". U.S. Geological Survey. http://pubs.usgs.gov/fs/2003/fs014-03/. Retrieved 2008-07-20.
- ^ Performance of Lifelines during the November 3, 2002 Denali, Alaska Earthquake by Mark Yashinsky and John Eidinger
- ^ Sorensen, S.P. and Meyer, K.J.: Effect of the Denali Fault Rupture on the Trans-Alaska Pipeline; Sixth U.S. Conference and Workshop on Lifeline Earthquake Engineering, ASCE, August 2003.
- ^ Crone,A.J., Personius,S.F., Craw,P.A., Haeussler,P.J. & Staft,L,.A. 2004.The Susitna Glacier Thrust Fault: Characteristics of Surface Ruptures on the Fault that Initiated the 2002 Denali Fault Earthquake. Bulletin of the Seismological Society of America; v. 94; p. S5-S22.
- ^ a b "2002 Denali Fault Earthquake". Science. http://www.sciencemag.org/cgi/content/abstract/300/5622/1113.
- ^ Dunham,E.M. & Archuleta,R.J. 2004.Evidence for a Supershear Transient during the 2002 Denali Fault Earthquake, Bulletin of the Seismological Society of America, 92, S256-S268
External links
- The 2002 Denali Fault earthquake Magnitude 7.9 near Denali National Park, AK USGS page on the 2002 Denali Earthquake
- AEIC page on the Denali earthquake
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