4.1

M4.1 Earthquake 101 km SSE of Isangel, Vanuatu — April 9, 2021

2021-04-09 18:26:35 UTC (2021-04-09) · approx. 5:26 AM UTC+11 local

MagnitudeM4.1(mb)
Time18:26 UTC≈ 5:26 AM UTC+11
Depth77.0 kmintermediate depth
Coordinates-20.334°, 169.761°
Felt byNo felt reports
Status✓ Reviewed by USGS

On April 9, 2021 at 18:26 UTC, a magnitude 4.1 intermediate depth earthquake struck 101 km SSE of Isangel, Vanuatu, at a depth of 77.0 km and coordinates -20.3342°, 169.7611°.

Physical scale: An earthquake of magnitude 4.1 releases seismic energy equivalent to roughly 21 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 406 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 5.4 mainshock that occurred 26 days ago 78 km S of Isangel, Vanuatu. 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.

Map showing earthquake epicenter at -20.33°, 169.76°

Earthquake Details

Magnitude
4.1 mb
Depth
77.0 km
intermediate depth
Location
-20.3342°N
169.7611°E

Technical Information

Event ID
us6000e1vb
Event Type
earthquake
Status
✓ Reviewed
Significance
259
Azimuthal Gap
187.0°
Min Station Distance
3.545°
RMS Residual
1.19 sec
Last Updated
2021-06-19 21:25:51 UTC

Common Questions

How strong was the magnitude 4.1 earthquake near Isangel, Vanuatu?

The magnitude 4.1 earthquake that struck 101 km SSE of Isangel, Vanuatu on April 9, 2021 at 18:26 UTC had a depth of 77.0 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 4.1 earthquakes can continue for several days and gradually diminish over time.

Is this the same earthquake as the M5.4 one earlier?

No. This magnitude 4.1 earthquake is an aftershock of the larger magnitude 5.4 mainshock that occurred earlier 78 km S of Isangel, Vanuatu. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.

Understanding This Data

Magnitude 4.1 earthquakes are often felt but rarely cause damage.

Learn more about magnitude →

Authoritative source: USGS event page (event ID: us6000e1vb). All scientific values on this page are sourced verbatim from the USGS feed.

Cite this page: EarthquakeTracker.org. (2021, April 9, 2021). M4.1 Earthquake 101 km SSE of Isangel, Vanuatu — April 9, 2021. Retrieved June 19, 2021 from https://www.earthquaketracker.org/earthquakes/event/us6000e1vb/