Abstract
In order to improve the locating capability for offshore earthquakes and tsunamis monitored off northeastern Taiwan, a cable-based ocean bottom seismographic observatory named “Marine Cable Hosted Observatory” (MACHO) was constructed and began operation at the end of 2011. The installed instruments of the observatory include a broadband seismometer, a strong-motion seismometer and a pressure gauge. In addition, various scientific instruments could be deployed for other purposes as well. At present, the seismic data are transmitted in real-time via a fiber cable, and integrated into the current inland seismographic network in Taiwan. The ocean bottom station has contributed to provide high quality seismic data already. According to observations from January 2012 to June 2013, there were a total of 15,168 earthquakes recorded by the system. By using the data from the ocean bottom station, the number of relocated earthquakes with an azimuth gap less than 180 degrees substantially increase about 34 %. Meanwhile, the root–mean–square of the time residual, the error in epicenter, and the error in depth of the earthquake locations decrease. Therefore, the implementation of MACHO has the advantage of extending the coverage of existing the Taiwan seismic network to the offshore, providing more accurate and real-time seismic data for offshore earthquakes monitoring. The results show that MACHO is crucial and necessary for monitoring seismic activities in northeastern Taiwan.
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Acknowledgments
We would like to express our gratefulness to the consultative committee of the MACHO project. The representative members include Prof. C.-S. Lee (National Taiwan Ocean University), Prof. C.-S. Liu, Prof. C.-F Chen (National Taiwan University), Dr. B.-Y. Kuo, Dr. C.-H. Lin, Dr. B.-S, Huang (Academia Sinica), Prof. C.-C. Wang (National Sun Yat-Sen University), and David Guan (Chunghwa Telecom). Due to their directions and comments proposed, the submarine system has finally built and begun in operation already. Dr. Y. Kaneda from the JAMSTEC (Japan Agency for Marine-Earth Science and Technology) is also acknowledged for providing the recent information on the developments of marine cable systems in Japan. Meanwhile, we want to thank Dr. C.-W. Kan and Dr. H.-C. Pu to help arranging the seismic data of this article. Reviews of this manuscript by Editor in Chief Dr. Amy Draut and three reviewers provided numerous constructive comments and had the paper much improved. The MACHO project was supported by the National Science Council and the Central Weather Bureau in Taiwan.
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Hsiao, NC., Lin, TW., Hsu, SK. et al. Improvement of earthquake locations with the Marine Cable Hosted Observatory (MACHO) offshore NE Taiwan. Mar Geophys Res 35, 327–336 (2014). https://doi.org/10.1007/s11001-013-9207-3
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DOI: https://doi.org/10.1007/s11001-013-9207-3