Earthquake

A strong and shallow earthquake registered by the USGS as M6.4 hit near the Rat Islands, Aleutian Islands, Alaska at 17:54 UTC on March 4, 2026. The agency is reporting a depth of 10 km (6.2 miles). EMSC is reporting the same magnitude and depth. According to the National Tsunami Warning Center (NTWC), there is no tsunami danger from this event.
The epicenter was located 224 km (139 miles) ESE of Attu Station (population 21), Alaska, and 1 097 km (682 miles) ESE of Klyuchi (population 10 000), Russia.
There is no tsunami danger for Alaska, British Columbia, Washington, Oregon, or California. Based on earthquake information and historic tsunami records, the earthquake is not expected to generate a tsunami, the National Tsunami Warning Center said.
The USGS issued a Green alert for shaking-related fatalities and economic losses. There is a low likelihood of casualties and damage, and there are likely to be no affected structures in this region.
The agency identified this event as the potential mainshock of an earthquake sequence. According to their aftershock forecast updated at 18:34 UTC, there is a 41% chance of one or more aftershocks larger than magnitude 5 within the next week.
At the time of the forecast, no magnitude 3 or higher aftershocks and no magnitude 5 or higher events had been recorded.
The USGS estimated that during the coming week until 18:30 UTC on March 11, there is more than 99% chance of additional earthquakes of magnitude 3 and above, with a most likely count between 2 and 640.
The probability of M4 and above earthquakes is 86%, with 0 to 64 expected. M5 and above events have a 41% probability, with 0 to 7 anticipated, while M6 and above events have a 9% chance, with 0 to 1 expected.
There is a 4% probability that this earthquake could act as a foreshock to a larger event of M6.4 or greater, and a 1% chance of magnitude 7 or higher aftershocks, according to the USGS.
This earthquake took place in the central segment of the Aleutian arc, a remote region stretching across the North Pacific Ocean where the Pacific Plate subducts beneath the North America Plate.
The Aleutian arc extends about 3 000 km (1 864 miles) from the Gulf of Alaska to the Kamchatka Peninsula and marks the boundary where the Pacific plate descends beneath the North America plate.
This subduction process creates the deep Aleutian Trench and the chain of volcanic islands that define the arc. Relative plate motion changes along its length, compressional in the east and more transform toward the west, resulting in regional differences in volcanism and seismic behavior.
In the central Aleutians, including the Rat Islands, the subduction angle is oblique and the Wadati-Benioff zone is well defined to depths near 200 km (124 miles).
The area regularly produces interplate thrust earthquakes and occasional strike-slip events within the overriding plate. Volcanic activity remains moderate, with many volcanoes distributed along the island chain.
Since 1900, the Aleutian arc has generated numerous great earthquakes larger than M7.5, including the May 7 1986 M8.0 Andreanof Islands event, the June 10 1996 M7.9 Andreanof Islands earthquake, and the November 17 2003 M7.8 Rat Islands earthquake. Six events of M8.3 or greater have ruptured nearly the entire shallow megathrust interface since 1906.
Among these, the April 1 1946 M8.6 Unimak Island earthquake generated a Pacific-wide tsunami with run-up heights up to 42 m (138 feet) on Unimak Island and fatal waves in Hilo, Hawaii.
The March 28 1964 M9.2 Prince William Sound earthquake, the second largest recorded earthquake globally, caused widespread damage and tsunami impacts along the Gulf of Alaska and the U.S. West Coast. A year later, the February 4 1965 M8.7 Rat Islands earthquake ruptured about 600 km (373 miles) of fault, producing tsunami run-ups to 10.7 m (35 feet) on Shemya Island.
Although tectonically active, the westernmost Aleutians experience fewer megathrust events due to the growing transform component of plate motion. Most earthquakes in that segment are shallow strike-slip events of M5–6, and volcanism diminishes westward toward the Commander Islands.