M6.4 Earthquake 73 km W of Talcahuano, Chile — September 21, 2021
2021-09-21 13:14:32 UTC (2021-09-21) · approx. 8:14 AM UTC-5 local
Felt by 83 people across nearby locations. Maximum shaking intensity MMI 4.7 (moderate).
On September 21, 2021 at 13:14 UTC, a magnitude 6.4 shallow crustal earthquake struck 73 km W of Talcahuano, Chile, at a depth of 18.8 km and coordinates -36.7771°, -73.9329°. The earthquake was reported felt by 83 peopleacross nearby locations, with a maximum shaking intensity of Modified Mercalli Intensity (MMI) 4.7 (moderate). The USGS PAGER system issued a green alert level for this event, indicating no significant casualties or damage expected. The nearest populated place is Lebu (population 22,345).
Physical scale: An earthquake of magnitude 6.4 releases seismic energy equivalent to roughly 60 kilotons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 16 km — a useful intuition for the size of the slip patch on the fault.
The epicenter is located in Chile, a region characterized by the Peru-Chile Trench, where the Nazca Plate subducts beneath South America at 65-80 mm per year. The nearest mapped fault system is the Peru-Chile Trench. View all earthquakes in Chile.
Learn more: Magnitude scale · Aftershock sequences
Nearest Populated Places
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 83 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
Population exposure (USGS PAGER)
Estimated population that experienced each level of shaking. Based on the USGS PAGER rapid impact assessment, which combines ShakeMap output with global population grids.
| Shaking intensity (MMI) | Description | Population exposed |
|---|---|---|
| MMI 3 | weak | 2,998,929 |
| MMI 4 | light | 1,255,903 |
| MMI 5 | moderate | 1,352 |
Earthquake Details
-73.9329°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 6.4 earthquake near Talcahuano, Chile?
The magnitude 6.4 earthquake that struck 73 km W of Talcahuano, Chile on September 21, 2021 at 13:14 UTC had a depth of 18.8 km. It was felt by 83 people with maximum shaking intensity of MMI 4.7 (moderate). For context, this was a strong earthquake capable of causing significant damage.
Where did the earthquake occur?
The earthquake epicenter was located at -36.7771°, -73.9329°, which is 73 km W of Talcahuano, Chile. The nearest populated place is Lebu (population 22,345). View all earthquakes in Chile.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 6.4 earthquakes can continue for weeks to months and gradually diminish over time.
Has Chile had earthquakes this big before?
The largest recorded earthquake in Chile was the M9.5 Great Chilean earthquake of May 22, 1960. Today's magnitude 6.4 event is significantly smaller than that historical record.
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Location
Authoritative source: USGS event page (event ID: us7000fd4k). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, September 21, 2021). M6.4 Earthquake 73 km W of Talcahuano, Chile — September 21, 2021. Retrieved December 22, 2025 from https://www.earthquaketracker.org/earthquakes/event/us7000fd4k/