Japan 8.3
on Sep 26, 2003

 

Tokyo, Sep 26, 2003

Two powerful earthquakes registering preliminary magnitudes of 8 and 7 on the Richter scale struck Hokkaido early Friday, injuring at least 420 people and leaving one man dead from a quake-related accident.

 

Magnitude 8.0 - HOKKAIDO, JAPAN REGION
2003 September 25 19:50:07 UTC
Preliminary Earthquake Report
U.S. Geological Survey, National Earthquake Information Center
World Data Center for Seismology, Denver

   A great earthquake occurred at 19:50:07 (UTC) on Thursday, September 25, 2003. 
   The magnitude 8.0 event has been located in the HOKKAIDO, JAPAN REGION. (This event 
   has been reviewed by a seismologist.) 

Magnitude 8.0 
Date-Time Thursday, September 25, 2003 at 19:50:07 (UTC)
  = Coordinated Universal Time 
Friday, September 26, 2003 at 4:50:07 AM 
  = local time at epicenter 
Time of Earthquake in other Time Zones 
Location 41.848°N, 143.770°E 
Depth 33 km (21 miles) set by location program 
Region HOKKAIDO, JAPAN REGION 

Distances 
  135 km (85 miles) SSW of Kushiro, Hokkaido, Japan
  240 km (150 miles) SSE of Asahikawa, Hokkaido, Japan
  240 km (150 miles) SE of Sapporo, Hokkaido, Japan
  770 km (480 miles) NNE of TOKYO, Japan

Location Uncertainty horizontal +/- 7 km (4.3 miles); depth fixed by location program 
Parameters Nst=185, Nph=185, Dmin=573.4 km, Rmss=1.01 sec, Gp= 32°,
M-type=moment magnitude (Mw), Version=9 
Source USGS NEIC (WDCS-D)

Tectonic Summary:

This subduction related earthquake initiated off the south-east shore of the island of Hokkaido, Japan, near the deep ocean trench. To the north of the event, the trench is called the Kuril trench and to the south it is called the Japan trench. This region marks the position where the Pacific plate begins to descend beneath Japan. Near the earthquake, the Pacific plate is moving west at a rate of about 8.2 cm per year relative to Eurasia.