M8.1 Earthquake near 2021 Kermadec Islands, New Zealand Earthquake — March 4, 2021
2021-03-04 19:28:33 UTC (2021-03-04) · approx. 7:28 AM UTC-12 local
Felt by 13 people across nearby locations. Maximum shaking intensity MMI 8.0 (violent).
On March 4, 2021 at 19:28 UTC, a magnitude 8.1 shallow crustal earthquake struck near 2021 Kermadec Islands, New Zealand Earthquake, at a depth of 28.9 km and coordinates -29.7228°, -177.2794°. The earthquake was reported felt by 13 peopleacross nearby locations, with a maximum shaking intensity of Modified Mercalli Intensity (MMI) 8.0 (violent). The USGS PAGER system issued a green alert level for this event, indicating no significant casualties or damage expected.
Physical scale: An earthquake of magnitude 8.1 releases seismic energy equivalent to roughly 21.3 megatons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 234 km — a useful intuition for the size of the slip patch on the fault.
The epicenter is located in New Zealand, a region characterized by the Hikurangi subduction zone in the North Island and the Alpine Fault in the South Island. The nearest mapped fault system is the Alpine Fault. View all earthquakes in New Zealand.
Learn more: Magnitude scale · Aftershock sequences
ShakeMap — predicted shaking intensity
Modeled ground-motion intensity contoured on the Modified Mercalli scale (MMI). Computed by the USGS from the moment-tensor solution and regional ground-motion prediction equations.
Source: U.S. Geological Survey ShakeMap. View interactive ShakeMap on USGS
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 13 citizen responses to the USGS Did You Feel It? system. Each colored zone represents the average MMI from reports in that area.
Source: U.S. Geological Survey Did You Feel It?. View on USGS · submit your own report
Earthquake Details
-177.2794°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 8.1 earthquake near 2021 Kermadec Islands, New Zealand Earthquake?
The magnitude 8.1 earthquake that struck near 2021 Kermadec Islands, New Zealand Earthquake on March 4, 2021 at 19:28 UTC had a depth of 28.9 km. It was felt by 13 people with maximum shaking intensity of MMI 8.0 (violent). For context, this was a strong earthquake capable of causing significant damage.
Where did the earthquake occur?
The earthquake epicenter was located at -29.7228°, -177.2794°, which is near 2021 Kermadec Islands, New Zealand Earthquake. View all earthquakes in New Zealand.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 8.1 earthquakes can continue for months to years and gradually diminish over time.
Has New Zealand had earthquakes this big before?
The largest recorded earthquake in New Zealand was the M8.2 Wairarapa earthquake of January 23, 1855. Today's magnitude 8.1 event is within one magnitude unit of that historical record.
Authoritative source: USGS event page (event ID: us7000dflf). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, March 4, 2021). M8.1 Earthquake near 2021 Kermadec Islands, New Zealand Earthquake — March 4, 2021. Retrieved December 22, 2025 from https://www.earthquaketracker.org/earthquakes/event/us7000dflf/