Data last collected:
QuakeFactsEvidence report · prepared 23 October 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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Nearby events with a similar magnitude
Catalog fields and provenance
Event ID
usp00033gg
Coordinates
52.056, -177.547
Network
us
Significance
630
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Questions this evidence can answer
01What exactly is this record?
Use the name, place, date and identifiers above to confirm that you have the right 65 km WNW of Adak, Alaska earthquake: magnitude 6.4 and depth | QuakeFacts record.
02What does the evidence establish?
Read the reported values with their units, coverage dates and source notes. Keep observed facts separate from estimates or interpretation.
03What should I verify next?
Follow the primary-source links and check the limitations before using this evidence for a decision, comparison or citation.
A closer look at 65 km WNW of Adak, Alaska
Depth in another unit
The recorded event depth of 93.3 km is approximately 57.97 miles below the source reference surface. Depth alone does not describe damage or local hazard.
Interpreting the recorded coordinates
The published position for 65 km WNW of Adak, Alaska is 52.056° north and 177.547° west. This expresses the source coordinates in hemispheres; it does not establish an entrance, public access or a safe route.