M4.9 Earthquake 125 km ESE of Madang, Papua New Guinea — October 31, 2023
2023-10-31 17:58:48 UTC (2023-10-31) · approx. 3:58 AM UTC+10 local
Aftershock of the M5.5 mainshock.
On October 31, 2023 at 17:58 UTC, a magnitude 4.9 shallow crustal earthquake struck 125 km ESE of Madang, Papua New Guinea, at a depth of 10.0 km and coordinates -5.5467°, 146.8710°. This earthquake was detected by 30 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 369, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 4.9 releases seismic energy equivalent to roughly 338 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.4 km — 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 5.5 mainshock that occurred 6 days ago 116 km ESE of Madang, Papua New Guinea. 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.
The epicenter is located in Papua New Guinea, a region characterized by the collision and subduction of the Pacific, Australian, and Solomon Sea plates. View all earthquakes in Papua New Guinea.
Learn more: Magnitude scale · Aftershock sequences
Earthquake Details
146.8710°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.9 earthquake near Madang, Papua New Guinea?
The magnitude 4.9 earthquake that struck 125 km ESE of Madang, Papua New Guinea on October 31, 2023 at 17:58 UTC had a depth of 10.0 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at -5.5467°, 146.8710°, which is 125 km ESE of Madang, Papua New Guinea. View all earthquakes in Papua New Guinea.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.9 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.5 one earlier?
No. This magnitude 4.9 earthquake is an aftershock of the larger magnitude 5.5 mainshock that occurred earlier 116 km ESE of Madang, Papua New Guinea. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
Has Papua New Guinea had earthquakes this big before?
The largest recorded earthquake in Papua New Guinea was the M8.0 New Britain earthquake of July 18, 1971. Today's magnitude 4.9 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: us7000l8nk). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, October 31, 2023). M4.9 Earthquake 125 km ESE of Madang, Papua New Guinea — October 31, 2023. Retrieved January 10, 2024 from https://www.earthquaketracker.org/earthquakes/event/us7000l8nk/