遠地実体波による1995年奄美大島近海地震の震源過程 Rupture Process of the 1995 Amami-Oshima-Kinkai Earthquakes Inferred from Teleseismic Data
Several earthquakes, which occurred near Kikai-jima from October 18 to November 1, 1995, are examined by means of teleseismic body waves. All the focal mechanisms determined for these earthquakes reveal normal-faults having a down-dip extension within a subducting slab. The main source parameters of the largest event are : (strike, dip, rake) = (208°, 75°, -92°); the seismic moment=5.9×10<SUP>19</SUP> [Nm] (<I>M</I><SUB>w</SUB>=7.1); fault area =6.0×10<SUP>8</SUP> [m<SUP>2</SUP>];dislocation=1.5 [m]; rupture duration=23 [s]; stress drop =10 [MPa]. In this event the rupture propagated unilaterally to SW direction. The second largest event ruptured the NE region, where the fault plane did not smoothly connected but formed a step to the main fault plane. It may be noteworthy that these earthquakes did not trigger any significant inter-plate earthquakes, suggesting that the adjacent plate interface may be intrinsically aseismic.
地學雜誌 106(4), 537-545, 1997-08-25
Tokyo Geographical Society