EARTHQUAKEM4.5

M4.5 earthquake near Honchō, Japan

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

A magnitude 4.5 earthquake struck 2 km (1 mi) north of Honchō, Japan on Wednesday, October 21, 2026 at 01:04 UTC, at a depth of 90 km (56 mi), according to the U.S. Geological Survey. At this intermediate depth, shaking spreads out before it reaches the surface.

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

MagnitudeM4.5
Depth90 km (56 mi)
Time (UTC)Oct 21 01:04
Location35.72°N 139.98°E
Nearest townHonchō · 2 km
Energy85 tons TNT
Aftershocks M2.5+0
Tsunami flagNo
Felt reports9
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Why here?

This earthquake struck about 104 km (65 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. At 90 km down, it most likely broke inside a plate that is sinking into the mantle beneath its neighbor, in what geologists call a subduction zone.

The red lines on the map are plate boundaries.

How strong was it?

Magnitude is logarithmic: each whole step releases about 32 times more energy. This magnitude 4.5 released roughly the energy of 85 tons of TNT. That is about 5.6 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 32,000,000 times more than this one.

Aftershocks

In the first 5 days 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 272 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 21, 2026 or earthquakes by day.

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