The Kochi cluster is named for the city of Kochi on the island of
Shikoku, Japan. The cluster includes most of Shikoku. It includes
earthquakes to a depth of ~50 km. The only M6 event is a 6.4 mb
earthquake on March 24, 2001. About half the events are recorded only to
near-regional distances (~5.0°) but they were retained because the
relocation suffered from instability without them. All events have depth
control from near-source and local distance readings, and many have
consistent estimates of focal depth from teleseismic depth phases. The
local seismic network is very dense and direct calibration is very
robust.
