M5.4 Earthquake 73 km SSW of George Town, Cayman Islands — October 16, 2021
2021-10-16 18:27:28 UTC (2021-10-16) · approx. 1:27 PM UTC-5 local
Felt by 14 people across nearby locations.
On October 16, 2021 at 18:27 UTC, a magnitude 5.4 shallow crustal earthquake struck 73 km SSW of George Town, Cayman Islands, at a depth of 10.0 km and coordinates 18.7014°, -81.7053°. The earthquake was reported felt by 14 peopleacross nearby locations, with a maximum shaking intensity of Modified Mercalli Intensity (MMI) 3.1 (light). The USGS PAGER system issued a green alert level for this event, indicating no significant casualties or damage expected. The nearest populated place is East End (population 1,639).
Physical scale: An earthquake of magnitude 5.4 releases seismic energy equivalent to roughly 2 kilotons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 3.2 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 14 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 | 59,643 |
Earthquake Details
-81.7053°E
Technical Information
Common Questions
How strong was the magnitude 5.4 earthquake near George Town, Cayman Islands?
The magnitude 5.4 earthquake that struck 73 km SSW of George Town, Cayman Islands on October 16, 2021 at 18:27 UTC had a depth of 10.0 km. It was felt by 14 people with maximum shaking intensity of MMI 3.1 (light). For context, this was a moderate earthquake that could be widely felt.
Where did the earthquake occur?
The earthquake epicenter was located at 18.7014°, -81.7053°, which is 73 km SSW of George Town, Cayman Islands. The nearest populated place is East End (population 1,639).
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 5.4 earthquakes can continue for days to weeks and gradually diminish over time.
Actions
Authoritative source: USGS event page (event ID: us6000fv9g). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, October 16, 2021). M5.4 Earthquake 73 km SSW of George Town, Cayman Islands — October 16, 2021. Retrieved December 22, 2025 from https://www.earthquaketracker.org/earthquakes/event/us6000fv9g/