Earthquake Research Institute

Office: ERI-1-709
TEL: +81-3-5841-8287
FAX: +81-3-3812-9417

Research Field

Ocean floor seismology

Current Research

My research is based on development of ocean bottom seismometers (OBSs) which is aimed to reveal earth interior beneath the ocean, where we could not obtain fine structure only from land observations. We make a group for marine seismology and ocean bottom solid earth geophysics to perform this aim, because we should work together for marineexperiments. My current studies are (1) development of a long-term broad-band OBS, (2) fine imaging of mantle beneath the Philippine Sea plate by using these OBSs, and (3) OBS surveys for crustal structure, seismic activity and aftershock distribution.
(1) and (2)To understand history of the earth well, it is now believed that we should research the earth from the view of plate and plume tectonics, then we need fine image of the whole earth interior. As 70% of the earth surface is covered by the sea, it has been difficult to obtain a high resolution structure of the mantle beneath the ocean, such as the western Pacific, only from land data. A long-term and broad-band observation is required to detect several large earthquakes used as signal sources, those can penetrate into the deep interior. The long-term broad-band OBS is designed for the aim above, and it is now on the way to improve the data quality through practical observations. By using 15 semi broad-band OBSs, we start a very long profile observation across the Philippine Sea from Dec. 1999, which is aimed to make a fine image of the subducting slab of the Pacific plate.
(3)Our group has been developing a Japanese standard OBS for mobile observations such as crustal structure survey and micro seismic activity or aftershock study. Observations are performed all over the world with foreign scientists and ships. Currently, I devote to a study about a large earthquake occurred south off Ishigaki island (1998/5/4), which located within the Philippine Sea plate. The aftershock observation by OBSs made a clear view of the fault plane and its relation with the sea bottom topography.

Representative Publications

1. D. Suetsugu, and H. Shiobara Broadband Ocean Bottom Seismology Annual Review of Earth and Planetary Sciences, 42, 27-43, 2014.
2. H. Shiobara, T. Kanazawa, and T. Isse New Step for Broadband Seismic Observation on the Sea Floor: BBOBS-NX IEEE-JOE, 38, 2, doi: 10.1109/JOE.2012.2222792, 396-405, 2013.
3. H. Shiobara, H. Sugioka, K. Mochizuki, S. Oki, T. Kanazawa, Y. Fukao and K. Suyehiro Double seismic zone in the North Mariana region revealed by long-term ocean bottom array observation Geophys. J. Int., 183, 3, 1455-1469, doi:10.1111/j.1365-246X.2010.04799.x, 2010.