InSAR Evidence for an active shallow thrust fault beneath the city of Spokane Washington, USA

摘要: [1] In 2001, a nearly five month long sequence of shallow, mostly small magnitude earthquakes occurred beneath the city Spokane, with population about 200,000, in state Washington. During most sequence, were not well located because seismic instrumentation was sparse. Despite poor-quality locations, earthquake hypocenters likely very residents near center both heard and felt many earthquakes. The combination poor locations lack known surface faults recent movement make assessing hazards related to swarm difficult. However, potential for destruction from shallow moderate-sized is high, example Christchurch New Zealand 2011, so hazard structure involved Spokane important. Using interferometric synthetic aperture radar (InSAR) data European Space Agency ERS2 ENVISAT satellites Canadian RADARSAT-1, satellite we are able show that slip on previously unknown thrust fault, which name Fault, source sequence. part Fault slipped during 2001 underlies north city, fault concentrated between ~0.3 2 km depth. Projecting buried plane gives possible trace strikes northeast into Spokane.