# M5.5 Earthquake: 5 km ESE of Asahi, Japan Updated 12:07 UTC, 29 Oct 2026. Canonical: https://monitorworld.app/earthquake/2026-10-28-m5-5-asahi-japan 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. ## Key numbers - Magnitude (USGS): **M5.5** (mww) - Depth: **41 km** (shallow) - USGS PAGER impact alert: **GREEN** (estimated impact) - Aftershocks M2.5+ so far: **2** (within 50 km) ## Nearest places - [6 KM] Asahi, Chiba, Japan (6 km from the epicentre, quake was ESE of here, population 64,690) - [12 KM] Hasaki, Chiba, Japan (12 km from the epicentre, quake was WSW of here, population 39,209) - [14 KM] Sōsa, Chiba, Japan (14 km from the epicentre, quake was E of here, population 35,674) - [14 KM] Yōkaichiba, Chiba, Japan (14 km from the epicentre, quake was E of here, population 32,651) - [55 KM] Chiba, Chiba, Japan (55 km from the epicentre, quake was ENE of here, population 979,768) - [36 KM] Narita, Japan (36 km from the epicentre, quake was ESE of here, population 133,000) - [43 KM] Sakura, Japan (43 km from the epicentre, quake was E of here, population 174,000) - [52 KM] Inzai, Japan (52 km from the epicentre, quake was ESE of here, population 105,000) - [53 KM] Yachiyo, Japan (53 km from the epicentre, quake was E of here, population 199,000) ## Strongest aftershocks so far - [LOW] [M4.7 · 6 km N of Asahi, Japan](https://earthquake.usgs.gov/earthquakes/eventpage/us7000ttt2) (2026-10-28 18:32 UTC, 41 km deep, USGS) - [LOW] [M4.3 · 10 km SSE of Hasaki, Japan](https://earthquake.usgs.gov/earthquakes/eventpage/us7000ttts) (2026-10-28 20:22 UTC, 26 km deep, USGS) ## 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 12:07 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)](https://www.jma.go.jp/jma/indexe.html) - [EMSC (European-Mediterranean Seismological Centre)](https://www.emsc-csem.org/) - [USGS event page for this quake](https://earthquake.usgs.gov/earthquakes/eventpage/us7000ttpe) (ShakeMap, PAGER, felt reports) - [tsunami.gov](https://www.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. ## FAQ ### 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. ## Get the app MonitorWorld is free on iPhone and Android, rated 4.7 from 52 ratings on the US App Store. - App Store: https://apps.apple.com/app/id6760610225 - Google Play: https://play.google.com/store/apps/details?id=app.monitorworld ## Sources - [USGS event page](https://earthquake.usgs.gov/earthquakes/eventpage/us7000ttpe): 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)](https://earthquake.usgs.gov/fdsnws/event/1/): the USGS earthquake catalog, used for the 30-year counts, history and aftershocks. Public domain. Credit: U.S. Geological Survey. - [USGS Geoserve](https://earthquake.usgs.gov/ws/geoserve/): nearest places to the epicentre. - [GeoNames](https://www.geonames.org/): large-city coordinates, CC BY 4.0. ## Related - [Japan earthquakes](https://monitorworld.app/live/earthquakes/japan): Live map and the 30-year normal in and around Japan. - [M6.5 Bonin Islands, Japan region](https://monitorworld.app/earthquake/2026-10-25-m6-5-bonin-islands-japan-region): 25 Oct 2026, 884 km from this quake. - [M5.8 Severo-Kuril’sk, Russia](https://monitorworld.app/earthquake/2026-10-06-m5-8-severo-kurilsk-russia): 6 Oct 2026, 1,834 km from this quake. - [Earthquakes today](https://monitorworld.app/live/earthquakes-today): Every M2.5+ quake of the past 24 hours. - [Earthquakes by region](https://monitorworld.app/live/earthquakes): All regions and every M5.5+ quake page. - [Tsunami warning today](https://monitorworld.app/live/tsunami-warning): Latest US tsunami bulletins. - [Earthquake near me](https://monitorworld.app/live/earthquake-near-me): Sort recent quakes by distance from you.