Minor 4.0 Earthquake Near San Antonio, Puerto Rico
A minor magnitude 4.0 earthquake struck 50 km NNW of San Antonio, Puerto Rico on Sunday, August 30, 2026 at 05:47:03 AM UTC. This shallow crustal event (53.0 km depth) released energy equivalent to approximately 13 tons of TNT. Here is the verified PR telemetry, live epicenter map, and ground shaking assessment.
(50 km NNW of)Seismic Telemetry Specifications
4.0MD
Minor Seismic Class
53.0km
Crustal Layer
18.912° N, 67.288° W
GPS Coordinates
13 tons
TNT Equivalent Power
PR
USGS Real-time Feed
Epicenter Location & Tectonic Fault Map
Is This Earthquake Dangerous?
A magnitude 4.0 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 indoors. Hanging objects swing slightly. Vibration like a passing light truck.
Felt only by a few persons at rest, especially on upper floors.
Did You Feel This Earthquake?
Help seismologists and community members map real-world ground shaking near Puerto Rico.
Your immediate response verifies shaking boundaries and helps ground-truth instrumental models.
What Does Magnitude 4.0 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?
Puerto Rico's seismicity is fundamentally governed by its tectonic setting: Located on the Puerto Rico-Virgin Islands microplate between the North American Plate to the north (Puerto Rico Trench) and Caribbean Plate to the south (Muertos Trough). Major regional fault structures include Puerto Rico Trench, Muertos Trough, Mona Passage Faults, Great Northern Puerto Rico Fault Zone.
Originating at a depth of 53.0 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 4.0. 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 Puerto Rico 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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