Broadband Seismic Observation

Seismic Observation of Solar Tachocline

Helioseismology has established the existence of a layer of strong gradients of angular velocity at the base of the solar convection zone. This layer (`tachocline') separates the convection zone exhibiting a strong latitudinal differential rotation from the radiative interior that rotates almost rigidly. Turbulence generated in the tachocline is likely to mix material in the upper radiative zon...

Broadband Seismic Methods for Towed-streamer Acquisition

Observation of equipartition of seismic waves.

Equipartition is a first principle in wave transport, based on the tendency of multiple scattering to homogenize phase space. We report observations of this principle for seismic waves created by earthquakes in Mexico. We find qualitative agreement with an equipartition model that accounts for mode conversions at the Earth's surface.

Development of Broadband Radar and Initial Observation

We have developed a broad-band radar which is the precipitation Ku-band doppler radar using the pulse compression technique (bandwidth=80MHz), and observed the rainfall. We could successfully obtain the vertical profile of the equivalent reflectivity factor Ze and doppler velocity with the high range-resolution from low altitude.

Rapid characterisation of large earthquakes by multiple seismic broadband arrays

An automatic procedure is presented to retrieve rupture parameters for large earthquakes along the Sunda arc subduction zone. The method is based on standard array analysis and broadband seismograms registered within 30– 100 epicentral distance. No assumptions on source mechanism are required. By means of semblance the coherency of P waveforms is analysed at separate large-aperture arrays. Wave...