Preliminary analysis of deformation at the Eurasia-Pacific-North America plate junction from GPS data

Autor: Minoru Kasahara, V. E. Levin, V. N. Chebrov, Evgenii Gordeev, V. F. Bakhtiarov, V. M. Pavlov, A. A. Gusev
Rok vydání: 2001
Předmět:
Zdroj: Geophysical Journal International. 147:189-198
ISSN: 1365-246X
0956-540X
DOI: 10.1046/j.0956-540x.2001.01515.x
Popis: SUMMARY Since 1996, a network of nine permanent GPS receivers has been recording, in continuous mode, the deformation on Kamchatka peninsula. The velocity and direction of the relative displacement of observation points are estimated from the entire data set for 1996‐2000. The deformation related to the large Kronotskoe earthquake (Mw=7.8, 1997 December 5) was identified at distances up to a few hundred kilometres. Half a month before this major event, large-amplitude pre-seismic deformation appeared at stations closest to its epicentral area. The deformation corresponds approximately to a double-couple slow event with Mw=7.7 located in the foreshock area, with an orientation that differs significantly from that of the main shock. Clear coseismic displacements were also observed. They match well those predicted by the published Harvard CMT solution. Large-scale post-seismic deformation was also recorded, again with a duration of about half a month, and a cumulative moment comparable to that of the ‘main’ shock. In addition to the transient effects of a large earthquake, data show a secular trend that reflects both the continuous plate motion and the elastic response to interplate coupling. Preliminary estimates of relative plate velocities for the North America, Okhotsk and Beringia plates are given based on the data from stations distant from the most active plate boundaries. Other stations seem to show mainly the elastic response of the Okhotsk and Beringia plates to their coupling with the subducting Pacific plate. At one station at least, the velocity of continuous motion underwent a significant change at the time of the Kronotskoe earthquake, probably indicating a related change in interplate coupling or the effects of mantle rheology.
Databáze: OpenAIRE
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