3.9

M3.9 Earthquake 73 km ESE of Sand Point, AlaskaOctober 16, 2024

2024-10-16 20:48:58 UTC (2024-10-16) · approx. 9:48 AM UTC-11 local

MagnitudeM3.9(ml)
Time20:48 UTC9:48 AM UTC-11
Depth11.7 kmshallow crustal
Coordinates55.115°, -159.406°
Felt by2DYFI responses· max MMI 4.0
Status✓ Reviewed by USGS

On October 16, 2024 at 20:48 UTC, a magnitude 3.9 shallow crustal earthquake struck 73 km ESE of Sand Point, Alaska, at a depth of 11.7 km and coordinates 55.1148°, -159.4059°. The earthquake was reported felt by 2 peopleacross nearby locations, with a maximum shaking intensity of Modified Mercalli Intensity (MMI) 4.0 (moderate).

Physical scale: An earthquake of magnitude 3.9 releases seismic energy equivalent to roughly 11 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 296 m — a useful intuition for the size of the slip patch on the fault.

Map showing earthquake epicenter at 55.11°, -159.41°

ShakeMap — predicted shaking intensity

Modeled ground-motion intensity contoured on the Modified Mercalli scale (MMI). Computed by the USGS from the moment-tensor solution and regional ground-motion prediction equations.

USGS ShakeMap intensity contours for the M3.9 earthquake near 73 km ESE of Sand Point, Alaska

Source: U.S. Geological Survey ShakeMap. View interactive ShakeMap on USGS

Did You Feel It? — community-reported shaking

Aggregated felt-report intensity from 2 citizen responses to the USGS Did You Feel It? system. Each colored zone represents the average MMI from reports in that area.

USGS DYFI community-reported intensity map for the M3.9 earthquake near 73 km ESE of Sand Point, Alaska

Source: U.S. Geological Survey Did You Feel It?. View on USGS · submit your own report

Earthquake Details

Magnitude
3.9 ml
Depth
11.7 km
shallow crustal
Location
55.1148°N
-159.4059°E
Felt Reports
2
DYFI responses
Intensity (MMI)
4.0
moderate
Community Intensity
2.2
CDI from reports

Technical Information

Event ID
us6000nz6z
Event Type
earthquake
Status
✓ Reviewed
Significance
234
Stations Used
21
Azimuthal Gap
234.0°
Min Station Distance
0.657°
RMS Residual
0.79 sec
Last Updated
2024-12-26 23:03:55 UTC

Common Questions

How strong was the magnitude 3.9 earthquake near Sand Point, Alaska?

The magnitude 3.9 earthquake that struck 73 km ESE of Sand Point, Alaska on October 16, 2024 at 20:48 UTC had a depth of 11.7 km. It was felt by 2 people with maximum shaking intensity of MMI 4.0 (moderate). For context, this was a minor earthquake typically detected only by instruments.

Were there aftershocks?

Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 3.9 earthquakes can continue for several days and gradually diminish over time.

Understanding This Data

Magnitude 3.9 earthquakes are typically only recorded by instruments.

Learn more about magnitude →

Authoritative source: USGS event page (event ID: us6000nz6z). All scientific values on this page are sourced verbatim from the USGS feed.

Cite this page: EarthquakeTracker.org. (2024, October 16, 2024). M3.9 Earthquake 73 km ESE of Sand Point, AlaskaOctober 16, 2024. Retrieved December 26, 2024 from https://www.earthquaketracker.org/earthquakes/event/us6000nz6z/