A massive shallow earthquake registered by the USGS as M8.2 hit near the coast of Alaska at 06:15 UTC on July 29, 2021. The agency is reporting a depth of 46.7 km (29 miles). EMSC is reporting it as M8.2 at depth of 30 km (18.6 miles).
The epicenter was located 90.9 km (56.5 km) ESE of Perryville, Alaska, United States.
A Tsunami Warning is in effect for SOUTH ALASKA AND THE ALASKA PENINSULA – Pacific coasts from Hinchinbrook Entrance, Alaska (145 km / 90 miles E of Seward) to Unimak Pass, Alaska (138 km / 80 miles NE of Unalaska); and ALEUTIAN ISLANDS – Unimak Pass, Alaska (128 km / 80 miles NE of Unalaska) to Samalga Pass, Alaska (48 km / 30 miles SW of Nikolski).
A Tsunami Advisory is in effect for SOUTHEAST ALASKA – The inner and outer coast from Cape Decision, Alaska (138 km / 85 miles SE of Sitka) to Cape Fairweather, Alaska (128 km / 80 miles SE of Yakutat), SOUTH ALASKA AND THE ALASKA PENINSULA – Pacific coasts from Cape Fairweather, Alaska (128 km / 80 miles SE of Yakutat) to Hinchinbrook Entrance, Alaska (145 km / 90 miles E of Seward); ALEUTIAN ISLANDS – Samalga Pass, Alaska (48 km / 30 miles SW of Nikolski) to Amchitka Pass, Alaska (201 km / 125 miles W of Adak) including the Pribilof Islands.
Tsunami Watch was issued for the State of Hawaii.
Image credit: TW/SAM, Google
The quake was followed by M6.2 at 06:23 UTC and M5.6 at 06:32 UTC.
Regional seismicity
The USGS advised everyone to be aware of the possibility of aftershocks, especially when in or around vulnerable structures such as unreinforced masonry buildings.
Aftershocks forecast
The USGS estimates the chance of more aftershocks as follows:
Within the next 1 Week until 06:40 UTC on August 5, 2021:
The chance of an earthquake of magnitude 3 or higher is > 99 %, and it is most likely that as few as 380 or as many as 33 000 such earthquakes may occur in the case that the sequence is re-invigorated by a larger aftershock. The chance of an earthquake of magnitude 5 or higher is > 99 %, and it is most likely that as few as 3 or as many as 330 such earthquakes may occur. The chance of an earthquake of magnitude 6 or higher is 87 %, and it is most likely that as few as 0 or as many as 33 such earthquakes may occur. The chance of an earthquake of magnitude 7 or higher is 36 %, and it is most likely that as few as 0 or as many as 4 such earthquakes may occur.
This report is based on preliminary data and is being updated.
Featured image credit: TW/SAM, Google
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