Application of Ocean Bottom Seismometer in Studying Marine Seismicity
- 1. 1. Jesse Hsia, DU. 2. Emmy Chang, NTU. 3. Ms. SPOT 4. Mr. Jian, NTU. Printed in August 28th, 2009 Application of Ocean Bottom Seismometer in Studying Marine Seismicity Institute of Oceanography, National Taiwan University aiwan is an island that located on the boundary between Philippine Plate and Eurasian Plate, and because of its active plate tectonic movements, it raises Taiwan to one of the tallest islands on the Planet Earth. Taiwan also sets on the Pacific Ring of Fire, therefore seismic events are occurring as matter of course. According to the seismic records, which I have observed from July of 2008 to September of 2008 from Taiwan Central Weather Bureau (CWB), I have noticed that about 90% of those 4033 seismic events were formed in the ocean off eastern Taiwan. Also I have noticed that the events from CWB can only be recorded a minimum amount due to the lack of seismological station distribution. It is obvious that the records from CWB were limited when the events were farther than Longitude of 122°E. That lack of seismic information were taken place in Ryukyu Arc and it is one of the most seismic active spot due to its geological formation as back-arc basin, which is submarine basins associated with island arc and subduction zone. Therefore it is important for us to know those specific seismic events that occurred in Ryukyu Arc. I have picked seismic events from July of 2008 to September of 2008 from Ocean-Bottom Seismometer of RATS (Ryukyu Arc Tectonic & Seismology) Report. As my result, the seismic events in Ryukyu Arc are still very active, therefore it is important for us to do a farther study in those areas. As above results, they indicate that Taiwan has a lack of seismic study in the ocean. It is important to develop Ocean-Bottom Seismometer (OBS) and Marine Cable Hosted Observatory (MACHO), therefore geophysicists can have good qualities of seismic data to calculate the energy released by seismic events and be able to pre- dict large seismic events for the sake of citizens of Taiwan. Abstract Top Left: Final check before dropping OBS into 5,000 ft. of Ocean Deep. Top Right: Collecting our OBS back, which indicated this trip was a success. Bottom: The scientific ship Ocean Researcher II for a cruise from July 29 to July 31, 2009 at Okinawa Through. According to this Map, about 90% of seismic events were formed in the Ocean. However CWB’s seismological station cannot fully record all of seismic events due to the lack of Seismological Network in the ocean. Moreover, CWB’s data were extremely imitated when events were farther than Longitude of 122°E. The Map also let us know that seismic events were very active along 122°E to 122.5°E and 24°N to 24.5°N from RATS’ data. ▲ OBS Station Fnet Station Rats Seismic Data CWB Seismic Data (2007, Oct. 30 ). In About MACHO. Retrieved Aug. 26, 2009, from http://macho.ncu.edu.tw/aboutMACHO.html (2009, Aug. 4 ). In WHOI: Instruments: Ocean-Bottom Seismometer. Retrieved Aug. 26, 2008, from http://viewInstrument.do?id=10347 Nakamura, M, and H. Katao. (2003). Microearthquakes and Faulting in the Southern Okinawa Trough. Tectonophysics, 372 (3-4), pp. 167-177. References