Kermadec and New Zealand Earthquakes

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Three notable earthquakes struck in the southern Pacific Ocean near the Kermadec Islands and New Zealand today, March 4, 2021.

A magnitude 8.1 earthquake near the Kermadec Trench was the third and largest earthquake of the three. This event is near the magnitude 7.4 earthquake that occurred earlier this afternoon, some 600 miles (950 km) north of New Zealand. While large, these earthquakes are remote and the USGS PAGER report is Green for fatalities and economic losses. The M8.1 earthquake is about 11 times larger than the earlier M 7.4 and occurred at a shallower depth (early estimates about 12 miles, or 20 km). The larger size and shallower depth increase the tsunami potential, and NOAA have released tsunami warnings for many islands in the southwest Pacific. The National Emergency Management Agency of New Zealand have also released a tsunami warning.

Map showing shaking intensity of the M7.3 New Zealand earthquake

Map shows shaking intensity of the March 4, 2021 New Zealand earthquake.

(Credit: USGS. Public domain.)

Like the preceding M7.4, the M 8.1 earthquake occurred as the result of thrust faulting at shallow depth, likely on the subduction zone interface between the Pacific and Australia plates. Large earthquakes in this region are common. While the M 7.4 earthquake was unlikely to have been triggered by static stress changes caused by the prior M 7.3 near New Zealand this morning, the M 8.1 and M 7.4 are directly related. The M 7.4 event can be considered a foreshock of the M 8.1. 

Further and updated information about 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 NE of Gisborne, New Zealand (usgs.gov)

USGS scientists expect that these events will trigger aftershocks, but these will decrease in frequency over time.

If you felt the M7.3 earthquake, report your experience on the “USGS Did You Feel It?” website for this event.

For information about tsunami watches, warnings or advisories, visit the National Oceanic and Atmospheric Administration (NOAA) tsunami website.

Follow our discussion about these events on twitter.

Learn more about the USGS Earthquake Hazards Program.

We will update this story if more information becomes available.

Earthquake Information/Resources