# M5.6 Earthquake: Southern Mid-Atlantic Ridge Updated 09:06 UTC, 29 Oct 2026. Canonical: https://monitorworld.app/earthquake/2026-09-29-m5-6-southern-mid-atlantic-ridge A **magnitude 5.6** earthquake struck southern Mid-Atlantic Ridge at 13:06 UTC on 29 Sep 2026, at a depth of 10 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. No M2.5+ aftershock had been listed within 50 km when this page was updated. ## Key numbers - Magnitude (USGS): **M5.6** (mww) - Depth: **10 km** (shallow) - USGS PAGER impact alert: **GREEN** (estimated impact) - Aftershocks M2.5+ so far: **0** (within 50 km) ## Nearest places - [399 KM] Edinburgh of the Seven Seas, Tristan da Cunha, Saint Helena (399 km from the epicentre, quake was WNW of here, population 271) - [2,850 KM] Arraial do Cabo, Rio de Janeiro, Brazil (2,850 km from the epicentre, quake was ESE of here, population 26,163) - [2,852 KM] Armação de Búzios, Rio de Janeiro, Brazil (2,852 km from the epicentre, quake was ESE of here, population 23,463) - [2,855 KM] São João da Barra, Rio de Janeiro, Brazil (2,855 km from the epicentre, quake was ESE of here, population 20,606) - [2,855 KM] Cabo Frio, Rio de Janeiro, Brazil (2,855 km from the epicentre, quake was ESE of here, population 108,239) ## Strongest aftershocks so far No M2.5+ aftershock listed yet. ## Key context ### Tectonic setting **Mid-Atlantic Ridge.** This is a mid-ocean ridge, where two plates pull apart and new sea floor forms. Quakes here are shallow and frequent, but they rarely pass M7 and happen far from people, so they seldom cause damage or a large tsunami. The USGS moment tensor shows strike-slip faulting: the two sides of the fault slid sideways past each other. At 10 km it was a very shallow quake: shallow quakes shake the ground above them hardest, so local damage depends on how close towns are. ### 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. USGS had no "Did You Feel It?" reports for this quake when this page was updated; remote and offshore quakes often get none. ### Aftershocks This page counts quakes of M2.5 or more within 50 km after the main shock, from the USGS catalog (last checked 09:06 UTC, 29 Oct 2026): 0 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 90 quakes of M5 or more within 250 km of this epicentre, about 1.8 a year. Since 1900 the same circle had 42 quakes of M5.6 or larger. Largest earlier quakes within 250 km, USGS catalog since 1900 (M6+). | Magnitude | Place (USGS) | Date | Depth | | --- | --- | --- | --- | | M7.0 | southern Mid-Atlantic Ridge | 2015-06-17 | 10 km | | M6.6 | southern Mid-Atlantic Ridge | 2005-02-16 | 10 km | | M6.4 | southern Mid-Atlantic Ridge | 1981-06-03 | 10 km | | M6.4 | southern Mid-Atlantic Ridge | 1989-09-13 | 12 km | | M6.3 | southern Mid-Atlantic Ridge | 1998-01-03 | 10 km | | M6.3 | southern Mid-Atlantic Ridge | 1998-04-25 | 10 km | | M6.3 | Tristan da Cunha region | 1960-08-20 | 15 km | | M6.2 | southern Mid-Atlantic Ridge | 1939-08-02 | 10 km | ### Official information - [EMSC (European-Mediterranean Seismological Centre)](https://www.emsc-csem.org/) - [USGS event page for this quake](https://earthquake.usgs.gov/earthquakes/eventpage/us6000tyc3) (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 22 Oct 2026 at 20:41 UTC. Magnitude, depth and location can still be revised; this page keeps the same address if they change. ## FAQ ### How strong was the earthquake southern Mid-Atlantic Ridge? USGS measured it at magnitude 5.6 (mww), 10 km deep. 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? USGS had no felt reports when this page was updated. That is common for offshore and remote quakes. If you felt it, you can report it on the USGS event page. ### Will there be more aftershocks? Aftershocks are likely to continue for days to weeks, becoming less frequent over time. So far 0 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 EMSC (European-Mediterranean Seismological Centre). ### 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/us6000tyc3): 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 - [M5.9 Bouvet Island region](https://monitorworld.app/earthquake/2026-10-24-m5-9-bouvet-island-region): 24 Oct 2026, 2,751 km from this quake. - [M6.8 central Mid-Atlantic Ridge](https://monitorworld.app/earthquake/2026-10-13-m6-8-central-mid-atlantic-ridge): 13 Oct 2026, 3,894 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.