Open AccessInSAR observations of aseismic slip associated with an earthquake swarm in the Columbia River flood basalts
Author(s) -
Wicks Charles,
Thelen Weston,
Weaver Craig,
Gomberg Joan,
Rohay Alan,
Bodin Paul
Publication year - 2011
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2011jb008433
Subject(s) - geology , earthquake swarm , seismology , interferometric synthetic aperture radar , seismic moment , slip (aerodynamics) , swarm behaviour , thrust fault , moment magnitude scale , geodetic datum , flood basalt , basalt , fault (geology) , geodesy , synthetic aperture radar , induced seismicity , tectonics , volcanism , remote sensing , geometry , thermodynamics , physics , mathematical optimization , mathematics , scaling
In 2009 a swarm of small shallow earthquakes occurred within the basalt flows of the Columbia River Basalt Group (CRBG). The swarm occurred within a dense seismic network in the U.S. Department of Energy’s Hanford Site. Data from the seismic network along with interferometric synthetic aperture radar (InSAR) data from the European Space Agency’s (ESA) ENVISAT satellite provide insight into the nature of the swarm. By modeling the InSAR deformation data we constructed a model that consists of a shallow thrust fault and a near horizontal fault. We suggest that the near horizontal lying fault is a bedding‐plane fault located between basalt flows. The geodetic moment of the modeled fault system is about eight times the cumulative seismic moment of the swarm. Precise location estimates of the swarm earthquakes indicate that the area of highest slip on the thrust fault, ∼70 mm of slip less than ∼0.5 km depth, was not located within the swarm cluster. Most of the slip on the faults appears to have progressed aseismically and we suggest that interbed sediments play a central role in the slip process.