Abstract
A brief review of continuous crustal movement observation conducted by Hokkaido University since 1971 is presented. The first observatory was established near Erimo Cape at the southern tip of Hokkaido island in 1971. Data from 13 vault type and 6 borehole type stations, which consist of three components of strain-meter and two components of tilt-meter, are transfered by a telemeter system with 24-bits ADC and 1 Hz sampling rate in 2006. In 1973 clear pre-, co-, and post-, seismic crustal deformations were recorded at Erimo station related to the 1973 Nemuro-hanto-oki (MW7.7) earthquake which occurred at 250 km north-east of the station. However, no clear pre-seismic crustal deformation was observed related to the 2003 Tokachi-oki (MW8.0) that occurred at 100km east of the station. Clear co-and post-seismic deformations related to this event were recorded at several stations. Especially, it should be noted that complete strain seismograms of Mw -8 event were recorded by the new recording system at MYR station nearest the source of the event.
