Three major earthquakes occurred today, March 4, 2021, in the southern Pacific Ocean near the Kermadec Islands and New Zealand.
An 8.1 magnitude earthquake near the Kermadec Trench was the third and largest of the three. This event is close to the magnitude 7.4 earthquake that occurred about 950 km north of New Zealand this afternoon. Although these earthquakes are significant, they are distant and the USGS PAGER report is green for fatalities and economic losses. The M8.1 magnitude quake is about 11 times larger than the previous M7.4 magnitude quake and occurred at a shallower depth (initial estimates are about 20 km). The larger size and shallower depth increase the potential for tsunamis, and NOAA has issued tsunami warnings for many islands in the Southwest Pacific. New Zealand’s National Emergency Management Agency has also issued a tsunami warning.
Like the previous M7.4 earthquake, the M8.1 earthquake was triggered by a shallow overthrust fault, probably at the interface of the subduction zone between the Pacific and Australian plates. Large earthquakes are common in this region. While it is unlikely that the M 7.4 earthquake was triggered by changes in static stress caused by the previous M 7.3 earthquake near New Zealand this morning, M 8.1 and M 7.4 are directly related. The M 7.4 event can be considered a precursor to M 8.1.
- Additional and updated information on the earthquake can be found here :
- M 8.1 – Kermadec Islands, New Zealand (usgs.gov).
- M 7.4 – Kermadec Islands, New Zealand (usgs.gov)
- M 7.3 – 174 km northeast of Gisborne, New Zealand (usgs.gov)
- USGS scientists expect these events to trigger aftershocks, but their frequency will decrease over time.
- If you felt the M7.3 magnitude earthquake, report your experience on the “USGS Did You Feel It” website for this event.
- For information on tsunami warnings, alerts, or advisories, visit the National Oceanic and Atmospheric Administration (NOAA) tsunami website.
- Follow our discussion of these events on Twitter.
- Learn more about the USGS Earthquake Hazards Program.
- We will update this story as more information becomes available.
- Earthquake information and resources
- USGS Earthquake Home Page
- Earthquake Frequently Asked Questions (FAQ).
- USGS roles, responsibilities, and research
- Did you feel it?