Spatial variations in the frequency-magnitude distribution of earthquakes in the southwestern Okinawa Trough
|Author(s)||Lin Jing-Yi1, 4, Sibuet Jean-Claude1, Lee Chao-Shing2, Hsu Shu-Kun3, Klingelhoefer Frauke1|
|Affiliation(s)||1 : IFREMER, Ctr Brest, F-29280 Plouzane, France.
2 : Natl Taiwan Ocean Univ, Inst Appl Geophys, Chilung 202, Taiwan.
3 : Natl Cent Univ, Inst Geophys, Chungli 32001, Taiwan.
4 : Coll France, Chaire Geodynam, F-13545 Aix En Provence 4, France.
|Source||Earth, Planets and Space (1343-8832) (TERRAPUB), 2007-05 , Vol. 59 , N. 4 , P. 221-225|
|WOS© Times Cited||8|
|Keyword(s)||Magma chamber, Slab tear, Southern Okinawa Trough backarc basin, B Values|
|Abstract||The relations between the frequency of occurrence and the magnitude of earthquakes are established in the southern Okinawa Trough for 2823 relocated earthquakes recorded during a passive ocean bottom seismometer experiment. Three high b-values areas are identified: (1) for an area offshore of the Ilan Plain, south of the andesitic Kueishantao Island from a depth of 50 km to the surface, thereby confirming the subduction component of the island andesites; (2) for a body lying along the 123.3 degrees E meridian at depths ranging from 0 to 50 km that may reflect the high temperature inflow rising up from a slab tear; (3) for a third cylindrical body about 15 km in diameter beneath the Cross Backarc Volcanic Trail, at depths ranging from 0 to 15 km. This anomaly might be related to the presence of a magma chamber at the base of the crust already evidenced by tomographic and geochemical results. The high b-values are generally linked to magmatic and geothermal activities, although most of the seismicity is linked to normal faulting processes in the southern Okinawa Trough.|