M4.6 Earthquake 102 km SSE of Hihifo, Tonga — July 29, 2023
2023-07-29 21:05:00 UTC (2023-07-29) · approx. 9:05 AM UTC-12 local
On July 29, 2023 at 21:05 UTC, a magnitude 4.6 shallow crustal earthquake struck 102 km SSE of Hihifo, Tonga, at a depth of 49.6 km and coordinates -16.7608°, -173.3197°. This earthquake was detected by 17 seismic stations with good location accuracy and was assigned a USGS significance rating of 326, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 4.6 releases seismic energy equivalent to roughly 120 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 899 m — a useful intuition for the size of the slip patch on the fault.
The epicenter is located in Tonga, a region characterized by the Tonga-Kermadec subduction zone, where the Pacific Plate descends at up to 240 mm per year — the fastest plate convergence on Earth. The nearest mapped fault system is the Tonga Trench. View all earthquakes in Tonga.
Learn more: Magnitude scale · Aftershock sequences
Earthquake Details
-173.3197°E
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Common Questions
How strong was the magnitude 4.6 earthquake near Hihifo, Tonga?
The magnitude 4.6 earthquake that struck 102 km SSE of Hihifo, Tonga on July 29, 2023 at 21:05 UTC had a depth of 49.6 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at -16.7608°, -173.3197°, which is 102 km SSE of Hihifo, Tonga. View all earthquakes in Tonga.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.6 earthquakes can continue for several days and gradually diminish over time.
Has Tonga had earthquakes this big before?
The largest recorded earthquake in Tonga was the M8.1 Tonga Trench earthquake of June 26, 1917. Today's magnitude 4.6 event is significantly smaller than that historical record.
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Location
Authoritative source: USGS event page (event ID: us6000kyfz). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, July 29, 2023). M4.6 Earthquake 102 km SSE of Hihifo, Tonga — July 29, 2023. Retrieved September 30, 2023 from https://www.earthquaketracker.org/earthquakes/event/us6000kyfz/