HR: 17:10h
AN: S34C-05    [Abstracts]
TI: Seismic and aseismic processes on the Psathopyrgos normal fault, western rift of Corinth, Greece.
AU: * Bernard, P
EM: bernard@ipgp.jussieu.fr
AF: IPGP, 4 Place Jussieu, Paris, 75252, France
AU: Boudin, F
AF: IPGP, 4 Place Jussieu, Paris, 75252, France
AU: Boudin, F
AF: DTM,Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC, 20015-1305, United States
AU: Linde, A
AF: DTM,Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC, 20015-1305, United States
AU: Sacks, S
AF: DTM,Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC, 20015-1305, United States
AU: Serpetsidaki, A
AF: Seismological Laboratory, University of Patras, Rio, Patras, 26500, Greece
AU: Patau, G
AF: IPGP, 4 Place Jussieu, Paris, 75252, France
AU: Diagourtas, D
AF: Department of Geophysics and Geothermy, University of Athens, Athens, 11527, Greece
AB: The western rift of Corinth (Greece) displays a fast opening rate (1.5 cm/year from GPS) and a very high, strongly fluctuating microseismic activity, monitored since 2000 by a local seismometer array. Several moderate to large earthquakes (M=6 to 6.7) have occurred historically on its segmented normal fault system, and one earthquake in this magnitude range is expected to occur in the coming decades. We focus here on the activity of the Psathopyrgos fault, the westernmost one in the rift ( 15 km away from the city of Patras), which did not rupture in historical time (more than 300 years), despite its clear morphological slip activity. This raises the question of possible creep on this fault, as a future coseismic release of more than 3 to 4 meters of slip on a 15 km long segment seems unlikely. A large seismic swarm occurred on this fault, in November-December 2002, with several events above magnitude 3, mostly located between 4 and 10 km in depth, and one reaching magnitude 3.5, at the exceptionally shallow depth of 3 km: this swarm suggests a large-scale activation of the whole fault, by creep or fluid migration. About 30 minutes before this M3.5 event, a strong compression signal is recorded oh the borehole dilatometer installed 15 km away in the Trizonia island, reaching its maximum at the time of the event, then gradually decaying. This signal can be modelled by a 10 cm aseismic creep involving the shallowest, eastern part of the fault. These observations raise the question of the possibility for mature normal faults to slip intermittently, both seismically and by creep.
DE: 1209 Tectonic deformation (6924)
DE: 7215 Earthquake source observations (1240)
DE: 7230 Seismicity and tectonics (1207, 1217, 1240, 1242)
DE: 8109 Continental tectonics: extensional (0905)
DE: 8118 Dynamics and mechanics of faulting (8004)
SC: Seismology [S]
MN: 2007 Fall Meeting