M4.5 Earthquake 59 km NE of Port-Olry, Vanuatu — August 4, 2023
2023-08-04 22:07:27 UTC (2023-08-04) · approx. 9:07 AM UTC+11 local
Aftershock of the M6.1 mainshock.
On August 4, 2023 at 22:07 UTC, a magnitude 4.5 intermediate depth earthquake struck 59 km NE of Port-Olry, Vanuatu, at a depth of 103.6 km and coordinates -14.6650°, 167.4691°. This earthquake was detected by 34 seismic stations with good location accuracy and was assigned a USGS significance rating of 312, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 4.5 releases seismic energy equivalent to roughly 85 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 767 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 6.1 mainshock that occurred 11 days ago 56 km NNE of Port-Olry, Vanuatu. Since the mainshock, the USGS has recorded 1 aftershocks in this area. Aftershock activity is expected to continue for weeks to months as stresses on surrounding faults redistribute.
The epicenter is located in Vanuatu, a region characterized by the New Hebrides subduction zone, where the Australian Plate subducts eastward at approximately 90 mm per year. View all earthquakes in Vanuatu.
Learn more: Magnitude scale · Aftershock sequences
Earthquake Details
167.4691°E
Technical Information
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Common Questions
How strong was the magnitude 4.5 earthquake near Port-Olry, Vanuatu?
The magnitude 4.5 earthquake that struck 59 km NE of Port-Olry, Vanuatu on August 4, 2023 at 22:07 UTC had a depth of 103.6 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at -14.6650°, 167.4691°, which is 59 km NE of Port-Olry, Vanuatu. View all earthquakes in Vanuatu.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.5 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M6.1 one earlier?
No. This magnitude 4.5 earthquake is an aftershock of the larger magnitude 6.1 mainshock that occurred earlier 56 km NNE of Port-Olry, Vanuatu. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
Has Vanuatu had earthquakes this big before?
The largest recorded earthquake in Vanuatu was the M7.9 Vanuatu earthquake of October 7, 2009. Today's magnitude 4.5 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: us6000kzes). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, August 4, 2023). M4.5 Earthquake 59 km NE of Port-Olry, Vanuatu — August 4, 2023. Retrieved October 7, 2023 from https://www.earthquaketracker.org/earthquakes/event/us6000kzes/