M5.1 Earthquake – RYUKYU ISLANDS, JAPAN

Published: 34 days ago•Sunday, September 20, 2026 at 7:28 AM UTC

A moderate magnitude 5.1 earthquake struck near RYUKYU ISLANDS, JAPAN at a depth of 70.0 km (intermediate focal zone), releasing seismic energy equivalent to approximately 674 tons of TNT. Here is the verified EMSC telemetry, interactive epicenter map, and ground shaking assessment.

5.1MAG
Moderate EarthquakeIntermediate Focal Depth
RYUKYU ISLANDS, JAPANJapan

Seismic Telemetry Specifications

Magnitude

5.1MW

Moderate Seismic Class

Focal Depth

70.0km

Upper Mantle

Epicenter

28.443° N, 129.380° E

GPS Coordinates

Energy Yield

674 tons

TNT Equivalent Power

Network Source

EMSC

USGS Real-time Feed

Epicenter Location & Tectonic Fault Map

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EMSC Source

Is This Earthquake Dangerous?

A magnitude 5.1 event is classified as a moderate earthquake. Can cause slight to moderate damage to poorly constructed buildings. Felt widely across nearby communities within dozens of kilometers.

Estimated Shaking Radius~100–250 km
Potential Damage Zone~30–50 km
Focal Depth EffectModerate Damping

Estimated Shaking Across Nearby Communities

The epicenter occurred in a remote or offshore marine sector with no major population centers situated within the primary ground shaking perimeter.

Did You Feel This Earthquake?

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Your immediate response verifies shaking boundaries and helps ground-truth instrumental models.

What Does Magnitude 5.1 Mean?

Earthquake strength is measured on a logarithmic scale. Compare this event with the full seismic scale:

1.0 – 2.9Micro
3.0 – 3.9Minor
4.0 – 4.9Light
5.0 – 5.9Moderate
This Event
6.0 – 6.9Strong
7.0 – 7.9Major
8.0+Great

Logarithmic Energy Multiplier

Because seismic scales are logarithmic, each whole integer increase represents:

10× Ground Motion Amplitude
The seismograph wave amplitude jumps tenfold for every 1.0 magnitude step.
~31.6× Radiated Kinetic Energy
Total energy release multiplies exponentially (101.5 ≈ 31.62 times per 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 70.0 km (Upper Mantle / Wadati-Benioff Zone (70–300 km)), this rupture occurred originated within the descending oceanic plate inside the upper mantle. shaking radiates over a wider geographic area with attenuated high frequencies.

Aftershock Outlook & Secondary Tremors

Following an earthquake of magnitude 5.1, an active aftershock sequence is expected over the coming days and weeks. In accordance with Omori's Law and Båth's Law of seismology, secondary tremors decrease in frequency over time, with the largest expected aftershock historically averaging approximately 1.0 to 1.2 magnitude units below the mainshock. Local residents should remain vigilant for secondary shaking, particularly when inspecting older structures or unreinforced masonry.

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Earthquake Safety Action Plan

Complete Safety Guide →
During the Shaking
  • •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.
Immediately After
  • •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.
Preparation & Kits
  • •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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