QuakeFactsEvidence report · prepared 2 September 2026https://quakes99.com/entity/usp00033gg
USGS usp00033gg
21 Mar 1987, 10:41
65 km WNW of Adak, Alaska
A magnitude 6.4 mw earthquake at 93.3 km depth.
Published location
Where is 65 km WNW of Adak, Alaska?
This locator uses the coordinates in the approved source record. It shows geographic context, not a site boundary, safety zone or property-risk area.
52.056000, -177.547000
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What the numbers mean
Magnitude measures event size; depth locates the source below the surface. Neither value alone establishes local damage or personal risk.
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Use local emergency authorities and the live USGS event page. This historical evidence page is not an alert service.
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Catalog fields and provenance
Event ID
usp00033gg
Coordinates
52.056, -177.547
Network
us
Significance
630