Geography Reference
In-Depth Information
Fig. 20.1
Number of missing and dead within each municipality (National Police Agency
Publicity
2011
)
20.2.2
Earthquake and Tsunami Hazard
Plate boundary earthquakes of about M7-8 have repeatedly occurred off the coast
of the Tohoku region (Obara
2012
). Focal regions of these earthquakes are sepa-
rated into eight zones. It was previously believed that each zone experienced such
earthquakes at an interval of a dozen to several hundred years (the asperity model).
However, in the case of the 2011 earthquake, six of the eight zones slipped together,
a phenomenon that had not been expected in this region. The plate boundary
displaced more than 50 m, resulting in the seafl oor being vertically uplifted by 5 m.
On land, it was also confi rmed from GPS data that the Oshika Peninsula moved
