Earthquake Research Institute, The University of Tokyo
Earthquakes, resulted from slip behaviors of faults, emit seismic waves that travel through Earth's interior to the ground surface. The seismic waves cause ground motion, which is sensed by seismometers and also people.
We, seismologists, use the ground motion recorded by seismometers as data to obtain insight into generation mechanisms of earthquakes and the structure of the Earth. Thanks to several hundreds of seismic observatories deployed at Japan islands in the past two decades, our understanding of seismic activity and subsurface structures beneath Japan has improved dramatically.
Nevertheless, there is still need of seafloor instrumentation, since many damaging earthquakes occur subduction zones located in offshore regions. Ocean-bottom seismometers (OBSs) have been developed for a long time here at Earthquake Research Institute, The University of Tokyo. These instruments offer continuous waveform data with excellent quality—now the data are applicable in sophisticated waveform analyses. One of my research interests is to clarify Earth's tectonic processes and the nature of seismogenic zones using data from OBSs.
I am also interested in developing analysis method itself. Conventionally, seismological studies read arrival times of major seismic phases from seismograms. With recent rapid progress in computation, it is now possible to use entire waveforms as input data. OBS data, however, is strongly influenced by reverberations within seawater and sediment layers that overprints later phases from deeper structures. Nobel techniques to overcome this difficulty are essential.