[SCG58-P36] Distribution of very low-frequency earthquakes in the Miyako Strait, central Ryukyu Trench
Keywords:Very Low Frequency Earthquake, Ryukyu Trench, Seismic
As a waveform of the broadband earthquake, we used the F-net stations of the NIED and the temporary stations (Hateruma, Tarama, Miyako, Kume, and Okinoerabu) which were set by Association for The Development of Earthquake Prediction (ADEP). The waveforms were band-pass filtered at the frequency range of 0.05–0.1Hz for seismogram of top and bottom, using the Seismic Analysis Code (SAC). Next, we searched the VLFE swarms which occurred between the Okinawa island to Miyako island from the VLFE catalog that is computed for the method of (Nakamura and Sunagawa, 2015), and we adopted the most remarkable events to the template. Next, we conducted the detection of the VLFE swarms which occurred in 5 October 2017 and epicentral determination.
Three VLFE events were detected and their hypocenters were determined during this period. The epicenters were located near 25.227N and 126.415E with a radius approximately 20 km. This position is almost the same as that obtained by Nakamura and Sunagawa (2015) and is distributed within a narrower area compared with the results of Nakamura and Sunagawa (2015). Although the accuracy of the location from the trench is poor because the seismic stations are parallel to the island arc, it indicates that the cluster of the VLFE in the region occur in a narrow area.