M4.0 Earthquake south of Tonga — June 18, 2023
2023-06-18 21:26:30 UTC (2023-06-18) · approx. 9:26 AM UTC-12 local
On June 18, 2023 at 21:26 UTC, a magnitude 4.0 shallow crustal earthquake struck south of Tonga, at a depth of 10.0 km and coordinates -24.2083°, -175.3792°.
Physical scale: An earthquake of magnitude 4.0 releases seismic energy equivalent to roughly 15 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 347 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 5.0 mainshock that occurred 24 days ago south of Tonga. Since the mainshock, the USGS has recorded 3 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Earthquake Details
-175.3792°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.0 earthquake south of Tonga?
The magnitude 4.0 earthquake that struck south of Tonga on June 18, 2023 at 21:26 UTC had a depth of 10.0 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 4.0 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.0 one earlier?
No. This magnitude 4.0 earthquake is an aftershock of the larger magnitude 5.0 mainshock that occurred earlier south of Tonga. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
Actions
Location
Understanding This Data
Magnitude 4.0 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us6000kn93). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, June 18, 2023). M4.0 Earthquake south of Tonga — June 18, 2023. Retrieved August 26, 2023 from https://www.earthquaketracker.org/earthquakes/event/us6000kn93/