M6.6 Earthquake 278 km NNE of Codrington, Antigua and Barbuda — July 10, 2023
2023-07-10 20:28:26 UTC (2023-07-10) · approx. 4:28 PM UTC-4 local
Felt by 417 people across surrounding communities.
On July 10, 2023 at 20:28 UTC, a magnitude 6.6 shallow crustal earthquake struck 278 km NNE of Codrington, Antigua and Barbuda, at a depth of 14.0 km and coordinates 20.0634°, -61.1021°. The earthquake was reported felt by 417 peopleacross surrounding communities, with a maximum shaking intensity of Modified Mercalli Intensity (MMI) 4.0 (light). The USGS PAGER system issued a green alert level for this event, indicating no significant casualties or damage expected. This earthquake was detected by 172 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 920, making it one of the more significant events of the week. The nearest populated place is Simpson Bay (population 5,000).
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.
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 417 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 | 7,518 |
| MMI 4 | light | 97,722 |
Earthquake Details
-61.1021°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 6.6 earthquake near Codrington, Antigua and Barbuda?
The magnitude 6.6 earthquake that struck 278 km NNE of Codrington, Antigua and Barbuda on July 10, 2023 at 20:28 UTC had a depth of 14.0 km. It was felt by 417 people with maximum shaking intensity of MMI 4.0 (light). For context, this was a strong earthquake capable of causing significant damage.
Where did the earthquake occur?
The earthquake epicenter was located at 20.0634°, -61.1021°, which is 278 km NNE of Codrington, Antigua and Barbuda. The nearest populated place is Simpson Bay (population 5,000).
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.
Actions
Authoritative source: USGS event page (event ID: us7000keq3). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, July 10, 2023). M6.6 Earthquake 278 km NNE of Codrington, Antigua and Barbuda — July 10, 2023. Retrieved September 16, 2023 from https://www.earthquaketracker.org/earthquakes/event/us7000keq3/