Four offshore earthquakes hit near Alaska Peninsula, while melting glacier could trigger major tsunami this year

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      While a series of offshore earthquakes occurred in proximity to the Gulf of Alaska this morning, scientists have warned that a melting glacier in the region could trigger a major tsunami.

      The first quake hit south of the Alaska Peninsula at 9:13 a.m. local time (10:13 a.m. B.C. time) today (May 20).

      It struck at a depth of 15 kilometres (nine miles) with an epicentre located 186 kilometres (115 miles) southeast of Perryville, Alaska, and 825 kilometres (511 miles) southwest of Anchorage, Alaska. The U.S. Geological Survey originally reported it as a 4.8-magnitude quake before reassessing it as a 4.6-magnitude seismic event.

      Then a second quake struck at 9:18 a.m. (10:18 a.m. B.C. time) today (May 20), with an epicentre at a depth of 10 kilometres (six miles) located 191 kilometres (119 miles) southeast of Perryville and 828 kilometres (513 miles) southwest of Anchorage. The U.S. Geological Survey initially measured it as a 4.2-magnitude quake before downgrading it to 4.1-magnitude.

      A third quake, measuring 3.2-magnitude occurred in the same area at 11:38 a.m. local time (12:38 p.m. B.C. time). The epicentre was located at 193 kilometres (120 miles) southeast of Perryville and 827 kilometres (514 miles) southwest of Anchorage.

      A fourth quake, measuring 3.0-magnitude, followed at 12:54 p.m. local time (1:54 p.m. B.C. time), with an epicentre 167 kilometres (104 miles) southeast of Perryville and 813 kilometres (505 miles) southwest of Anchorage.

      Prince William Sound

      While none of these seismic events resulted in any tsunami warnings, scientists are warning that a potential landslide in Prince William Sound on Alaska's southern coast could trigger a large tsunami.

      Several scientists–with expertise in climate change, landslides, and tsunamis—signed an open letter, dated May 14, warning the melting Barry Glacier in Barry Arm, located about 97 kilometres (60 miles) east of Anchorage, could cause an unstable slope to fall into Harriman Ford. Up to 500 individuals, including fishermen and boaters, are in the area during the summer.

      The falling rock, which could be up to millions of tons, into the water could trigger one of the largest tsunamis to hit the northern region. 

      Scientists believe the landslide will likely happen within the next year, but could occur any time within the next 20 years.

      Heavy rainfall, rapid snowmelt, or thawing permafrost could be make the landslide a fast-moving one.

      The 7.7-magnitude 1958 Lituya Bay earthquake in the Alaska Pandhandle triggered a rockslide that caused a megatsunami, which reached up to approximately 525 metres (1,720 feet), that is considered the largest and most significant tsunami in modern times. 

      You can follow Craig Takeuchi on Twitter at @cinecraig or on Facebook.