INL Seismic Monitoring Annual Report: January 1, 2006 - December 31, 2006

Payne, S. J. ; Carpenter, N. S. ; Hodges, J. M. ; Berg, R. G.

Idaho National Laboratory

关键词: Eastern Snake River Plain;    Monitoring;    58 - Geosciences;    Snake River Plain Earthquakes;    Earthquakes;   

DOI  :  10.2172/919567
RP-ID  :  INL/EXT-07-13057
RP-ID  :  DE-AC07-99ID-13727
RP-ID  :  919567

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来源: UNT Digital Library

【 摘 要 】

During 2006, the Idaho National Laboratory (INL) recorded 1998 independent triggers from earthquakes both within the region and from around the world. Fifteen small to moderate size earthquakes ranging in magnitude from 3.0 to 4.5 occurred within and outside the 161-km (100-mile) radius of INL. There were 357 earthquakes with magnitudes up to 4.5 that occurred within the 161-km radius of the INL. The majority of earthquakes occurred in the Basin and Range Province surrounding the eastern Snake River Plain (ESRP). The largest of these earthquakes had a body-wave magnitude (mb) 4.5 and occurred on February 5, 2006. It was located northeast of Spencer, Idaho near the east-west trending Centennial fault along the Idaho-Montana border. The earthquake did not trigger SMAs located within INL buildings. Three earthquakes occurred within the ESRP, two of which occurred within the INL boundaries. One earthquake of coda magnitude (Mc) 1.7 occurred on October 18, 2006 and was located southeast of Pocatello, Idaho. The two earthquakes within the INL boundaries included the local magnitude (ML) 2.0 on July 31, 2006 located near the southern termination of the Lemhi fault and the Mc 0.4 on August 6, 2006 located near the center of INL. The ML 2.0 earthquake was well recorded by most of the INL seismic stations and had a focal depth of 8.98 km. First motions were used to compute a focal mechanism, which indicated normal faulting along one of two possible fault planes that may strike N76ºW and dip 70±3ºSW or strike N55ºW and dip 20±13ºNE. Slip along a normal fault that strikes N76ºW and dips 70±3ºSW is consistent with slip along a possible segment of the NW-trending Lemhi normal fault.