M5.5 Earthquake: 5 km ESE of Asahi, Japan

Updated 11:27 UTC · 29 Oct 2026

A magnitude 5.5 earthquake struck 5 km ESE of Asahi, Japan at 15:07 UTC on 28 Oct 2026, at a depth of 41 km, reported by USGS. USGS PAGER issued a green alert: little or no damage and a low chance of deaths. USGS did not set a tsunami flag for this quake. So far 2 aftershocks of M2.5+ have been recorded within 50 km, the largest a M4.7.

M5.5

Magnitude (USGS)

mww

41 km

Depth

shallow

GREEN

USGS PAGER impact alert

estimated impact

Aftershocks M2.5+ so far

within 50 km

[ fig. 1 ] M5.5 EPICENTRE, AFTERSHOCKS AND PAST QUAKESThis quakeAftershock M5+AftershockPast M6+

USGS · updated 11:27 UTC 2026-10-29Tap a point for details · pinch or ctrl + scroll to zoomTrack this live in the app ›

Nearest places

Asahi, Chiba, Japan6 km from the epicentre · quake was ESE of here · population 64,6906 KM
Hasaki, Chiba, Japan12 km from the epicentre · quake was WSW of here · population 39,20912 KM
Sōsa, Chiba, Japan14 km from the epicentre · quake was E of here · population 35,67414 KM
Yōkaichiba, Chiba, Japan14 km from the epicentre · quake was E of here · population 32,65114 KM
Chiba, Chiba, Japan55 km from the epicentre · quake was ENE of here · population 979,76855 KM
Narita, Japan36 km from the epicentre · quake was ESE of here · population 133,00036 KM
Sakura, Japan43 km from the epicentre · quake was E of here · population 174,00043 KM
Inzai, Japan52 km from the epicentre · quake was ESE of here · population 105,00052 KM
Yachiyo, Japan53 km from the epicentre · quake was E of here · population 199,00053 KM

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Strongest aftershocks so far

Key context

Tectonic setting

Japan Trench. Off northern Japan the Pacific Plate subducts westward beneath Honshu and Hokkaido along the Japan and Kuril trenches. This boundary produced the M9.1 Tohoku earthquake and tsunami of 11 March 2011, and it has M6-7 quakes every few years.

The USGS moment tensor shows thrust (reverse) faulting: one block of crust was pushed up and over the other, the typical motion where plates converge.

At 41 km it was a shallow quake (USGS counts 0 to 70 km as shallow). Most damaging quakes are in this range.

Shaking and impact

USGS PAGER estimates the impact from the shaking and the number of people exposed. For this quake it issued a green alert: little or no damage and a low chance of deaths (fatality alert: green, economic loss alert: green). PAGER is an early estimate and can change as reports come in.

The USGS ShakeMap estimates the strongest shaking at intensity V on the Modified Mercalli scale (moderate).

58 people sent a "Did You Feel It?" report to USGS, with the strongest reported intensity IV (light).

Estimated shaking in nearby towns, from USGS PAGER.
Town	Population	Estimated intensity
Tokyo	37,732,000	IV (light)
Yokohama	3,757,630	IV (light)
Kawasaki	1,539,522	IV (light)
Saitama	1,325,843	IV (light)
Chiba	981,738	IV (light)
Setagaya	940,509	IV (light)
Nerima	742,463	IV (light)
Ota-ku	737,187	IV (light)

Aftershocks

This page counts quakes of M2.5 or more within 50 km after the main shock, from the USGS catalog (last checked 11:27 UTC, 29 Oct 2026): 2 aftershocks so far.

Aftershocks are normal after a quake of this size. They usually become less frequent over days and weeks, but a strong aftershock can still happen, and in a few sequences a later quake is larger. No one can predict their exact time or size; follow the official agency for your area.

Earthquake history within 250 km

Since 1976, USGS lists 1,331 quakes of M5 or more within 250 km of this epicentre, about 27 a year. Since 1900 the same circle had 707 quakes of M5.5 or larger.

Largest earlier quakes within 250 km, USGS catalog since 1900 (M6+).
Magnitude	Place (USGS)	Date	Depth
M8.0	5 km SSE of ?iso, Japan	1923-09-01	15 km
M7.9	174 km SE of Katsuura, Japan	1953-11-25	25 km
M7.9	47 km E of ?arai, Japan	2011-03-11	43 km
M7.9	5 km E of Tateyama, Japan	1923-09-02	15 km
M7.8	105 km E of Iwaki, Japan	1938-11-05	35 km
M7.7	69 km ESE of Kitaibaraki, Japan	1938-05-23	15 km
M7.7	116 km E of Namie, Japan	1938-11-06	30 km
M7.7	116 km ESE of Namie, Japan	1938-11-05	35 km

Official information

Japan Meteorological Agency (JMA)
EMSC (European-Mediterranean Seismological Centre)
USGS event page for this quake (ShakeMap, PAGER, felt reports)
tsunami.gov for US tsunami bulletins

Data status

USGS review status: reviewed. Magnitude type: mww. USGS last updated this event on 29 Oct 2026 at 09:29 UTC. Magnitude, depth and location can still be revised; this page keeps the same address if they change.

Questions and answers

How strong was the earthquake near Asahi, Japan?

USGS measured it at magnitude 5.5 (mww), 41 km deep. The strongest estimated shaking was intensity V (moderate). Quakes of M5 to 5.9 are classed as moderate.

Was there a tsunami?

USGS did not set a tsunami flag for this quake. If you are on a coast and feel strong or long shaking, move to high ground anyway, and follow local officials.

Was the earthquake felt?

Yes. 58 people reported it to USGS "Did You Feel It?", with reports up to intensity IV.

Will there be more aftershocks?

Aftershocks are likely to continue for days to weeks, becoming less frequent over time. So far 2 aftershocks of M2.5+ have been listed. Most sequences do not produce a larger quake, but some do. No one can predict the time or size of the next one; follow Japan Meteorological Agency (JMA).

What should I do after a strong earthquake?

Expect aftershocks: Drop, Cover and Hold On when shaking starts again. Check for injuries and damage, stay out of damaged buildings, and use text messages instead of calls so emergency lines stay free. On a coast, move to high ground after strong shaking. Follow your local officials.

Related live pages

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Sources

USGS event page: magnitude, location, ShakeMap, PAGER and Did You Feel It? data for this event. Public domain. Credit: U.S. Geological Survey.
USGS ComCat (FDSN event web service): the USGS earthquake catalog, used for the 30-year counts, history and aftershocks. Public domain. Credit: U.S. Geological Survey.
USGS Geoserve: nearest places to the epicentre.
GeoNames: large-city coordinates, CC BY 4.0.

Page built 11:27 UTC, 2026-10-29. Full list: data sources and method.