M6.6 Earthquake 80 km WSW of Vallenar, Chile — October 31, 2023
2023-10-31 12:33:43 UTC (2023-10-31) · approx. 7:33 AM UTC-5 local
Felt by 71 people across nearby locations. Maximum shaking intensity MMI 6.6 (very strong).
On October 31, 2023 at 12:33 UTC, a magnitude 6.6 shallow crustal earthquake struck 80 km WSW of Vallenar, Chile, at a depth of 34.0 km and coordinates -28.7431°, -71.5573°. The earthquake was reported felt by 71 peopleacross nearby locations, with a maximum shaking intensity of Modified Mercalli Intensity (MMI) 6.6 (very strong). The USGS PAGER system issued a green alert level for this event, indicating no significant casualties or damage expected. This earthquake was detected by 169 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 719, making it a moderate-impact event. The nearest populated place is Vallenar (population 44,895).
Physical scale: An earthquake of magnitude 6.6 releases seismic energy equivalent to roughly 120 kilotons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 22 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 71 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 | 3,759 |
| MMI 4 | light | 743,504 |
| MMI 5 | moderate | 57,665 |
| MMI 6 | strong | 14,555 |
| MMI 7 | very strong | 537 |
Earthquake Details
-71.5573°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 6.6 earthquake near Vallenar, Chile?
The magnitude 6.6 earthquake that struck 80 km WSW of Vallenar, Chile on October 31, 2023 at 12:33 UTC had a depth of 34.0 km. It was felt by 71 people with maximum shaking intensity of MMI 6.6 (very strong). For context, this was a strong earthquake capable of causing significant damage.
Where did the earthquake occur?
The earthquake epicenter was located at -28.7431°, -71.5573°, which is 80 km WSW of Vallenar, Chile. The nearest populated place is Vallenar (population 44,895). View all earthquakes in Chile.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 6.6 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 6.6 event is significantly smaller than that historical record.
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Location
Authoritative source: USGS event page (event ID: us7000l7si). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, October 31, 2023). M6.6 Earthquake 80 km WSW of Vallenar, Chile — October 31, 2023. Retrieved January 10, 2024 from https://www.earthquaketracker.org/earthquakes/event/us7000l7si/