M 8.2 - 134 km SSW of Kushiro, Japan
- 2003-09-25 19:50:06 (UTC)
- 41.815°N 143.910°E
- 27.0 km depth
Official Magnitude updated 24-Jun-2019
Reference:
Duputel, Z; Rivera, L; Kanamori, H; Hayes, G. (2012).
W phase source inversion for moderate to large earhquakes (1990 - 2010),
Geophysical Journal International, 189(2), 1125-1147.
Interactive Map Regional Information Felt Report - Tell Us! 000000Responses Contribute to citizen science. Please tell us about your experience.
- ShakeMap
IXmmi 
Estimated Intensity Map Ground Failure - Landslide Estimate
Extensive area affected
Limited population exposed
- Liquefaction Estimate
Significant area affected
Significant population exposed
Origin - Review Status
- REVIEWED
- Magnitude
- 8.2 mww
- Depth
- 27.0 km
- Time
- 2003-09-25 19:50:06 UTC
Moment Tensor Fault Plane Solution Finite Fault 
Cross-section of slip distribution. View Nearby Seismicity - Time Range
± Three Weeks - Search Radius
250.0 km - Magnitude Range
≥ 5.0
Contributors US
USGS National Earthquake Information Center, PDE
Tectonic Summary
The September 25, 2003, M 8.3 earthquake near Hokkaido, Japan, occurred as the result of shallow thrust faulting on or near the plate interface between the overriding North America plate (which extends into the northeast corner of the Eurasian landmass) and the subducting Pacific plate. At the location of this earthquake, the Pacific plate is moving west-northwest at a velocity of about 82 mm/yr relative to the North America plate, subducting beneath Japan and Eurasia at the Japan and Kuril-Kamchatka Trenches to the east of the September 25th earthquake.
In addition to experiencing great-sized thrust earthquakes that originate on the interface between these plates, eastern Hokkaido also experiences large earthquakes that originate from the interior of the subducted Pacific plate. The earthquakes of March 4, 1952 (30 km north of the 2003 earthquake), and May 16, 1968 (110 km southwest) were interface-thrust earthquakes, whereas the earthquake of January 15, 1993 (170 km north) occurred within the interior of the subducted Pacific plate. The September 25, 2003, earthquake appears to have involved rupture of the same section of the plate interface that ruptured in 1952.
While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Thrust-faulting events of the size of the July 15, 2003, earthquake are typically about 230x80 km (length x width); modeling of this earthquake implies dimensions of about 100x120 km, mostly down-dip of the hypocenter.
The last great-sized earthquake (M 8+) in the world was a M 8.4 event that occurred on June 23, 2001, near the coast of Peru. That earthquake resulted in at least 75 fatalities, including 26 killed by the associated tsunami.
Hayes et al. (2016) Tectonic summaries of magnitude 7 and greater earthquakes from 2000 to 2015, USGS Open-File Report 2016-1192. (5.2 MB PDF)
Summary Poster
