M 4.0 - 115 km NE of Esashi, Japan
(115 km NE of)Seismic Telemetry Specifications
4.0MB
Light Seismic Class
300.6km
Deep Mantle
45.603° N, 143.720° E
GPS Coordinates
15 tons
TNT Equivalent Power
US
USGS Real-time Feed
Epicenter Location & Tectonic Fault Map
Is This Earthquake Dangerous?
A magnitude 4.0 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 Radius
~50–100 km
Potential Damage Zone
< 15 km (very minor)
Focal Depth Effect
Deep Damping
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:
10× Ground Motion Amplitude
The seismograph wave amplitude jumps by tenfold for every 1.0 magnitude step.
~31.6× Radiated Kinetic Energy
Total energy release increases exponentially (101.5 ≈ 31.62 times per magnitude unit).
Why Did This Earthquake Happen?
Japan sits at the complex collision intersection of four major tectonic plates: the Pacific, Philippine Sea, Eurasian, and North American plates. Subduction of the Pacific Plate beneath the Japanese archipelago creates intense strain that releases as high-frequency megathrust earthquakes and volcanic activity along the Pacific Ring of Fire.
Originating at a depth of 300.6 km (Deep Mantle Transition Zone (>300 km)), this rupture occurred generated deep within earth's mantle under immense hydrostatic pressure. surface shaking is significantly damped despite large energy release.
Earthquake Safety Action Plan
- •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 moderate and strong events.
- •Avoid damaged structures and listen to official emergency broadcasts.
- •Maintain a 72-hour emergency go-bag with water, non-perishable food, and first aid.
- •Anchor heavy furniture, water heaters, and appliances to structural wall studs.
- •Establish a family emergency communication protocol and meeting point.
Did You Feel This Earthquake?
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