Minor 3.9 Earthquake – OFFSHORE CHIAPAS, MEXICO
A minor magnitude 3.9 earthquake struck near OFFSHORE CHIAPAS, MEXICO on Friday, September 18, 2026 at 07:18:19 PM UTC. This shallow crustal event (12.6 km depth) released energy equivalent to approximately 11 tons of TNT. Here is the verified UNM telemetry, live epicenter map, and ground shaking assessment.
Seismic Telemetry Specifications
3.9M
Minor Seismic Class
12.6km
Crustal Layer
14.779° N, 93.247° W
GPS Coordinates
11 tons
TNT Equivalent Power
UNM
USGS Real-time Feed
Epicenter Location & Tectonic Fault Map
Is This Earthquake Dangerous?
A magnitude 3.9 event is classified as a minor earthquake. Often felt by people indoors, especially on upper floors. Hanging objects may swing slightly; structural damage is extremely rare.
Estimated Shaking Across Nearby Communities
Felt by almost no one except under extraordinarily favorable conditions.
Did You Feel This Earthquake?
Help seismologists and community members map real-world ground shaking near Mexico.
Your immediate response verifies shaking boundaries and helps ground-truth instrumental models.
What Does Magnitude 3.9 Mean?
Earthquake strength is measured on a logarithmic scale. Compare this event with the full seismic scale:
Logarithmic Energy Multiplier
Because seismic scales are logarithmic, each whole integer increase represents:
Why Did This Earthquake Happen?
Southern and central Mexico lies directly above the Middle America Trench, where the oceanic Cocos and Rivera plates subduct beneath the North American Plate. This active subduction margin produces frequent intermediate and megathrust seismic events.
Originating at a depth of 12.6 km (Earth's Crust (0–70 km)), this rupture occurred occurred within the brittle upper crust. shallow earthquakes produce the highest peak ground acceleration and the sharpest surface shaking.
Aftershock Outlook & Secondary Tremors
Seismologists note that minor aftershocks remain common in the 24 to 48 hours following tremors of magnitude 3.9. According to statistical seismic models, there is roughly a 5% probability of a subsequent event of equal or greater strength occurring in the same fault zone. Residents in Mexico are advised to check living spaces for unsecured items.
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Earthquake Safety Action Plan
Complete Safety Guide →- •Drop, Cover, and Hold On: Take cover beneath a sturdy table or desk.
- •Stay indoors away from exterior glass windows and heavy unanchored fixtures.
- •If outdoors, move into an open area away from power lines and building facades.
- •Inspect utilities for damaged gas lines, water leaks, or electrical hazards.
- •Expect Aftershocks: Secondary tremors frequently strike after significant events.
- •Avoid damaged structures and listen to official emergency broadcasts.
- •Maintain a 72-hour emergency go-bag with water, food, and first aid.
- •Anchor heavy furniture, water heaters, and appliances to structural studs.
- •Establish a family emergency communication protocol and meeting point.
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