PT  - JOURNAL ARTICLE
AU  - West, Michael
AU  - Sánchez, John J.
AU  - McNutt, Stephen R.
TI  - Periodically Triggered Seismicity at Mount Wrangell, Alaska, After the Sumatra Earthquake
AID  - 10.1126/science.1112462
DP  - 2005 May 20
TA  - Science
PG  - 1144--1146
VI  - 308
IP  - 5725
4099  - http://science.sciencemag.org/content/308/5725/1144.short
4100  - http://science.sciencemag.org/content/308/5725/1144.full
SO  - Science2005 May 20; 308
AB  - As surface waves from the 26 December 2004 earthquake in Sumatra swept across Alaska, they triggered an 11-minute swarm of 14 local earthquakes near Mount Wrangell, almost 11,000 kilometers away. Earthquakes occurred at intervals of 20 to 30 seconds, in phase with the largest positive vertical ground displacements during the Rayleigh surface waves. We were able to observe this correlation because of the combination of unusually long surface waves and seismic stations near the local earthquakes. This phase of Rayleigh wave motion was dominated by horizontal extensional stresses reaching 25 kilopascals. These observations imply that local events were triggered by simple shear failure on normal faults.