EARTHQUAKEM5.5

M5.5 earthquake near Asahi, Japan

Map: the earthquake near Asahi, Japan, with plate boundaries

A magnitude 5.5 earthquake struck 5 km (3 mi) east-southeast of Asahi, Japan on Wednesday, October 28, 2026 at 15:07 UTC, at a depth of 41 km (26 mi), according to the U.S. Geological Survey. Shallow quakes like this one shake the surface hardest. The nearest city of a million or more people is Tokyo, about 86 km (54 mi) away.

USGS’s PAGER impact estimate is GREEN: little or no damage expected.

32 people reported feeling it to USGS “Did You Feel It?”.

MagnitudeM5.5
Depth41 km (26 mi)
Time (UTC)Oct 28 15:07
Location35.70°N 140.71°E
Nearest townAsahi · 5 km
Energy3 kilotons TNT
Aftershocks M2.5+0
Tsunami flagNo
PAGER alertGREEN
Felt reports32
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Why here?

This earthquake struck about 121 km (75 mi) from the boundary between the North American and Philippine Sea plates. Most earthquakes happen along plate boundaries like this one, where the pieces of Earth’s outer shell collide, pull apart or grind past each other. Stress builds up over years until the rock suddenly slips.

The red lines on the map are plate boundaries.

What kind of fault?

USGS’s analysis of the seismic waves shows it was a thrust (reverse) earthquake: one block of crust was pushed up and over another, as happens where plates collide.

Shaking and impact

The strongest shaking USGS estimates was intensity 5 on the Modified Mercalli scale: moderate. About 116,253 people were exposed to moderate shaking or stronger (intensity 5 and up). USGS’s PAGER system estimates it most likely caused no deaths (90 percent probability). Early estimates are revised as reports come in.

How strong was it?

Magnitude is logarithmic: each whole step releases about 32 times more energy. This magnitude 5.5 released roughly the energy of 3 kilotons of TNT. That is about 178 times the energy of a magnitude 4.0, a quake people nearby feel but that rarely causes damage. The strongest earthquake ever recorded, magnitude 9.5 in Chile in 1960, released about 1,000,000 times more than this one.

Aftershocks

In the first 2 hours after it, USGS recorded no smaller earthquakes of magnitude 2.5 or more within 100 km (62 mi).

Outside the United States, USGS mainly lists quakes of about magnitude 4 and up, so smaller aftershocks there are undercounted.

Earthquake history here

Before this earthquake, USGS had recorded 287 earthquakes of magnitude 6 or larger within 300 km (186 mi) since 1900. The strongest:

Official details, updates and the shaking map: USGS event page.

See every earthquake on October 28, 2026 or earthquakes by day.

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