Data last collected:
QuakeFactsEvidence report · prepared 25 October 2026https://quakes99.com/entity/usp00010rm
USGS usp00010rm
20 May 1979, 09:14
104 km SSE of Ugashik, Alaska
A magnitude 6.4 mb earthquake at 71 km depth.
Published location
Where is 104 km SSE of Ugashik, 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.
56.647000, -156.725000
Open the interactive map ↗Map data © OpenStreetMap contributors
What the numbers mean
Magnitude measures event size; depth locates the source below the surface. Neither value alone establishes local damage or personal risk.
Need a current safety answer?
Use local emergency authorities and the live USGS event page. This historical evidence page is not an alert service.
Continue exploring
Nearby events with a similar magnitude
Catalog fields and provenance
Event ID
usp00010rm
Coordinates
56.647, -156.725
Network
us
Significance
630
Use this record
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 104 km SSE of Ugashik, 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 104 km SSE of Ugashik, Alaska
Depth in another unit
The recorded event depth of 71 km is approximately 44.12 miles below the source reference surface. Depth alone does not describe damage or local hazard.
Interpreting the recorded coordinates
The published position for 104 km SSE of Ugashik, Alaska is 56.647° north and 156.725° west. This expresses the source coordinates in hemispheres; it does not establish an entrance, public access or a safe route.