Light 4.7 Earthquake Near Olancha, United States
A light magnitude 4.7 earthquake struck 20km NE of Olancha, United States on Saturday, May 23, 2009 at 10:58:32 PM UTC. This shallow crustal event (-0.6 km depth) released energy equivalent to approximately 188 tons of TNT. Here is the verified CI telemetry, live epicenter map, and ground shaking assessment.
(20km NE of)Seismic Telemetry Specifications
4.7ML
Light Seismic Class
-0.6km
Crustal Layer
36.396° N, 117.838° W
GPS Coordinates
188 tons
TNT Equivalent Power
CI
USGS Real-time Feed
Epicenter Location & Tectonic Fault Map
Is This Earthquake Dangerous?
A magnitude 4.7 event is classified as a light earthquake. Noticeable shaking of indoor objects and rattling doors/windows. Generally causes none to slight non-structural damage in older buildings.
Estimated Shaking Across Nearby Communities
Felt by all. Glassware broken, books knocked off shelves, minor plaster cracks.
Felt only by a few persons at rest, especially on upper floors.
Felt only by a few persons at rest, especially on upper floors.
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What Does Magnitude 4.7 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?
United States's seismicity is fundamentally governed by its tectonic setting: Pacific Plate sliding past North American Plate along San Andreas; Juan de Fuca subducting along Cascadia; Pacific subduction along the Aleutian Trench. Major regional fault structures include San Andreas Fault System, Cascadia Subduction Zone, Aleutian Megathrust, Hayward Fault, New Madrid Seismic Zone.
Originating at a depth of -0.6 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 4.7. 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 United States 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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