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Sequence of strong intraplate earthquakes in the Kodiak Island Region, Alaska in 1999–2001
Author(s) -
Ratchkovski Natalia A.,
Hansen Roger A.
Publication year - 2001
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2001gl013416
Subject(s) - seismology , geology , aftershock , intraplate earthquake , hypocenter , seismometer , subduction , seismic moment , focal mechanism , moment tensor , north american plate , sequence (biology) , pacific plate , fault (geology) , induced seismicity , tectonics , oceanography , genetics , deformation (meteorology) , biology
A sequence of strong earthquakes was registered in 1999–2001 in the Kodiak Island region of the Alaska‐Aleutian subduction zone. Two Mw 7 earthquakes occurred in December, 1999 and January, 2001 and an Mw 6.5 event occurred in July, 2000. These events and their aftershocks recorded by the regional seismograph network were relocated using a Joint Hypocenter Determination (JHD) method. Regional broadband data were used to obtain seismic moment tensors for the main shocks and their largest aftershocks. Relocation and moment tensor inversion results indicate that these events originated inside the subducting Pacific plate. The focal mechanisms indicate down‐dip tension with the fault planes being nearly vertical and parallel to the strike direction of the subducting plate. The 1999 and 2000 events were located down‐dip of the locked portion of the megathrust, while the 2001 event was located directly beneath it.