Katsuhisa Kanda

Monitoring of earthquake induced motions and damage with optical motion tracking

Optical motion tracking technologies using surveillance cameras have been applied to the measurement of earthquake induced motions and detection of seismic damage to interior elements to reduce risks in a building. We have developed methods for detecting structural collapse and overturning of interior elements. Shaking table tests were carried out to evaluate the optical systems ability to detect damage. The movements of two-storey frame structures and rectangular pieces of wood on the shaking table were monitored using conventional video cameras. Results from this exploratory study showed that optical measurements are promising in terms of capturing small to large deformations and identifying various types of seismic damage.

Inversion analysis of the 2004 off the Kii peninsula earthquakes using seismic intensity data

An inversion analysis has been developed to evaluate short-period radiation zones on an earthquake fault plane using seismic intensity data. It is robust and widely applicable even for historical earthquakes without ground motion, tsunami and geodetic data observed by instruments. It was applied to the 2004 off the Kii peninsula earthquakes that occurred in the Philippine Sea plate along the Nankai Trough. The short-period seismic wave radiation zone of each event during the 2004 off the Kii peninsula earthquakes from the inversion analysis was included in epicenter area of the corresponding aftershocks and slipped fault zone derived from the waveform inversion analysis as well. It may be also found that there were slip areas where little short period energy radiated. It also applied to the 1899/3/7 earthquake whose felt area was similar to that of the 2004 off the Kii peninsula earthquakes. However, it was indicated that the short-period radiation zones of the 1899 earthquake was located near the coast of the Kii peninsula and departed from that of the 2004 earthquake. The 1899 event might be an intermediate-depth earthquake in the Philippine Sea plate or a relative small interplate event at the west margin of the Tonankai earthquake source region.