M 7.6 - Volcano Islands, Japan region
- 2000-03-28 11:00:22 (UTC)
- 22.338°N 143.730°E
- 126.5 km depth
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Origin - Review Status
- REVIEWED
- Magnitude
- 7.6 mwc
- Depth
- 126.5 km
- Time
- 2000-03-28 11:00:22 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
≥ 4.0
Contributors US
USGS National Earthquake Information Center, PDE
Tectonic Summary
The March 28, 2000, M 7.6 earthquake in the Volcano Islands, Japan region, occurred as the result of normal faulting at intermediate depth within the subducted Pacific plate, approximately 127 km beneath the Philippine Sea southeast of Japan. Focal mechanism solutions for the earthquake indicate that rupture occurred on either a near-vertical normal fault or on a very shallowly dipping oblique normal fault within the interior of the subducted Pacific slab. Of these two possible fault orientations, finite-fault modeling of globally recorded seismic data is more consistent with slip on the steep, southeast-striking fault. At the location of this earthquake, the Pacific plate moves westward with respect to the Philippine Sea plate at a velocity of about 31 mm/yr.
Earthquakes like this event, with focal depths between 70 and 300 km, are commonly termed “intermediate-depth” earthquakes. Intermediate-depth earthquakes represent deformation within subducted slabs rather than at the shallow plate interface between subducting and overriding tectonic plates. They typically cause less damage on the ground surface above their foci than is the case with similar-magnitude shallow-focus earthquakes, but large intermediate-depth earthquakes may be felt at great distance from their epicenters. “Deep-focus” earthquakes, those with focal depths greater than 300 km, also occur in the subducted Pacific plate beneath the Mariana Island Arc. Earthquakes have been reliably located to depths of about 630 km beneath the Mariana Island Arc.
Historically, this area has hosted several other large earthquakes. Within 400 km of the March 28th event there have been seven earthquakes from M 6.5 to M 6.9 over the preceding 40 years. All of these earthquakes likely occurred either on or close to the Pacific-Philippine Sea plate subduction zone interface. None are known to have any associated fatalities or damage.
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)