M4.4 Earthquake 86 km WSW of Hihifo, Tonga — September 16, 2021
2021-09-16 23:36:12 UTC (2021-09-16) · approx. 11:36 AM UTC-12 local
On September 16, 2021 at 23:36 UTC, a magnitude 4.4 intermediate depth earthquake struck 86 km WSW of Hihifo, Tonga, at a depth of 189.9 km and coordinates -16.2217°, -174.5534°.
Physical scale: An earthquake of magnitude 4.4 releases seismic energy equivalent to roughly 60 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 655 m — a useful intuition for the size of the slip patch on the fault.
This earthquake is part of an ongoing aftershock sequence following the magnitude 5.2 mainshock that occurred 18 hours ago 109 km W of Hihifo, Tonga. Since the mainshock, the USGS has recorded 1 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Earthquake Details
-174.5534°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.4 earthquake near Hihifo, Tonga?
The magnitude 4.4 earthquake that struck 86 km WSW of Hihifo, Tonga on September 16, 2021 at 23:36 UTC had a depth of 189.9 km. For context, this was a light earthquake commonly felt near the epicenter.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.4 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.2 one earlier?
No. This magnitude 4.4 earthquake is an aftershock of the larger magnitude 5.2 mainshock that occurred earlier 109 km W of Hihifo, Tonga. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
Actions
Location
Understanding This Data
Magnitude 4.4 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us7000fdhi). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, September 16, 2021). M4.4 Earthquake 86 km WSW of Hihifo, Tonga — September 16, 2021. Retrieved November 23, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000fdhi/