3.8

M3.8 Earthquake 257 km NW of Houma, TongaJuly 27, 2025

2025-07-27 20:17:12 UTC (2025-07-27) · approx. 8:17 AM UTC-12 local

MagnitudeM3.8(mb)
Time20:17 UTC8:17 AM UTC-12
Depth533.9 kmdeep-focus
Coordinates-19.822°, -177.319°
Felt byNo felt reports
Status✓ Reviewed by USGS

On July 27, 2025 at 20:17 UTC, a magnitude 3.8 deep-focus earthquake struck 257 km NW of Houma, Tonga, at a depth of 533.9 km and coordinates -19.8222°, -177.3193°.

Physical scale: An earthquake of magnitude 3.8 releases seismic energy equivalent to roughly 7.6 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 252 m — a useful intuition for the size of the slip patch on the fault.

Map showing earthquake epicenter at -19.82°, -177.32°

Earthquake Details

Magnitude
3.8 mb
Depth
533.9 km
deep-focus
Location
-19.8222°N
-177.3193°E

Technical Information

Event ID
us6000qz5p
Event Type
earthquake
Status
✓ Reviewed
Significance
222
Stations Used
18
Azimuthal Gap
126.0°
Min Station Distance
4.579°
RMS Residual
0.55 sec
Last Updated
2025-10-11 20:57:49 UTC

Common Questions

How strong was the magnitude 3.8 earthquake near Houma, Tonga?

The magnitude 3.8 earthquake that struck 257 km NW of Houma, Tonga on July 27, 2025 at 20:17 UTC had a depth of 533.9 km. 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 3.8 earthquakes can continue for several days and gradually diminish over time.

Understanding This Data

Magnitude 3.8 earthquakes are typically only recorded by instruments.

Learn more about magnitude →

Authoritative source: USGS event page (event ID: us6000qz5p). All scientific values on this page are sourced verbatim from the USGS feed.

Cite this page: EarthquakeTracker.org. (2025, July 27, 2025). M3.8 Earthquake 257 km NW of Houma, TongaJuly 27, 2025. Retrieved October 11, 2025 from https://www.earthquaketracker.org/earthquakes/event/us6000qz5p/