Moment Magnitude (Mw):
Greenwich Mean Date:
HOKKAIDO, JAPAN REGION
An earthquake registering a preliminary magnitude of Mw 6.0 occurred at 4:54 p.m. local epicentral time, February 20 (07:54 UTC, February 20) off the souther coast of Hokkaido, Japan. The quake was centered about 25 miles south of Urakawa on the southern peninsula, or about 15 miles southeast of Sapporo. The quake had an unusually low Surface wave magnitude compared to the Moment magnitude. The focal mechanism was nearly pure thrust along a north-northeast trending plane. The depth was determined to be about 38 km.
Although there have been no reports as of yet, the quakes is likely to have been widely felt.
Note: This was only the third global earthquake to register 6.0 or stronger for the month. During the 1990's, only two other months have recorded this few a number of 6.0s, January 1992, and February 1993. However, since 1960 there have been at least 25 months with three or less +6.0 quakes, and six of these months recorded only 1 +6.0 temblor!