Data last collected:
QuakeFactsEvidence report · prepared 19 October 2026https://quakes99.com/entity/usp0004m1x
USGS usp0004m1x
23 Jan 1991, 01:12
Rat Islands, Aleutian Islands, Alaska
A magnitude 6.4 mw earthquake at 108.4 km depth.
Published location
Where is Rat Islands, Aleutian Islands, 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.
51.965000, 178.838000
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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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Nearby events with a similar magnitude
Catalog fields and provenance
Event ID
usp0004m1x
Coordinates
51.965, 178.838
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 Rat Islands, Aleutian Islands, 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 Rat Islands, Aleutian Islands, Alaska
Depth in another unit
The recorded event depth of 108.4 km is approximately 67.36 miles below the source reference surface. Depth alone does not describe damage or local hazard.
Interpreting the recorded coordinates
The published position for Rat Islands, Aleutian Islands, Alaska is 51.965° north and 178.838° east. This expresses the source coordinates in hemispheres; it does not establish an entrance, public access or a safe route.