Second Large Earthquake in Two Months Strikes Alaska's Aleutian Islands
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Pastor Dale Morgan
Sep 3, 2010, 3:04:56 PM9/3/10
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Great Earthquakes In Diverse Places
Second Large Earthquake in Two Months Strikes Alaska's Aleutian Islands
Sep 3, 2010 Jennifer Young
Alaska is a highly seismically active area. A second major earthquake in less than two months struck the Aleutian Island chain in September 2010.
For the second time in a matter of months a large earthquake (of a magnitude greater than 6.0) has struck Alaska’s Aleutian Island chain, on 3 September 2010. The Aleutian Islands are a volcanic island arc, part of the seismically active region known as the Pacific Ring of Fire, where a significant proportion of the earth’s earthquake activity occurs.
The Alaskan Earthquake of 3 September 2010
Preliminary information from the United States Geological Survey (USGS) indicates that the earthquake was of magnitude 6.3 (initial magnitudes are often later revised) and occurred close to Adak, in the Andreanof Islands, roughly 1200 miles west of Anchorage, in the early hours of the morning, local time.
USGS information indicates that the earthquake took place at a depth of around 30 miles below the surface, at the Aleutian subduction zone. At this point on the earth’s surface, the Pacific tectonic plate is being subsumed below the crust to the north, a zone where stress builds up and is released as earthquakes. No damage had been reported at the time of writing.
In the past earthquakes in Alaska have been responsible for tsunamis, some of which have caused significant damage and loss of life in the Pacific islands and along the North America’s Pacific coast. Though the September 3 earthquake was significant, no tsunami warning was issued, although it was possible that some areas could experience what were described as ‘non-damaging sea level changes’ (NOAA West Coast and Alaska Tsunami Warning Center, “Tsunami Information Statement”).
Recent Seismic Events in Alaska
The Aleutian Islands lie on Pacific Rim and, as a consequence of the geological setting, are regularly shaken by earthquake activity. The subduction of the Pacific Plate also generates extensive volcanic activity: the Smithsonian Institute’s Global Volcanism Program lists 40 volcanoes in the island chain (Smithsonian Institute, “Volcanoes of Alaska”).
A study of the USGS data listings indicates that minor earthquakes are extremely common in the Aleutians: USGS data show that over 80 earthquakes of greater than magnitude 2.5 occurred in the island chain between 10th and 27th August 2010, the majority in the Fox Islands. Other earthquakes occurred elsewhere in Alaska, though these were fewer in number (USGS).
The pattern of seismicity displayed along the Aleutians is one of regular small earthquakes punctuated by occasional larger ones and, very rarely, major events. The September 2010 event follows relatively soon after the previous large earthquake to strike the Aleutians, the 6.1M (initially reported as 6.7) event which occurred on 17 July 2010, some way to the west in the Fox Islands. Prior to that event, the last significant earthquake event recorded was a magnitude 6.6 which occurred in April 2008.
Read more at Suite101: Second Large Earthquake in Two Months Strikes Aleutian Islands http://www.suite101.com/content/second-large-earthquake-in-two-months-strikes-aleutian-islands-a281905#ixzz0yUjtq5lt
Second Large Earthquake in Two Months Strikes Alaska's Aleutian Islands
Sep 3, 2010 Jennifer Young
Alaska is a highly seismically active area. A second major earthquake in less than two months struck the Aleutian Island chain in September 2010.
For the second time in a matter of months a large earthquake (of a magnitude greater than 6.0) has struck Alaska’s Aleutian Island chain, on 3 September 2010. The Aleutian Islands are a volcanic island arc, part of the seismically active region known as the Pacific Ring of Fire, where a significant proportion of the earth’s earthquake activity occurs.
The Alaskan Earthquake of 3 September 2010
Preliminary information from the United States Geological Survey (USGS) indicates that the earthquake was of magnitude 6.3 (initial magnitudes are often later revised) and occurred close to Adak, in the Andreanof Islands, roughly 1200 miles west of Anchorage, in the early hours of the morning, local time.
USGS information indicates that the earthquake took place at a depth of around 30 miles below the surface, at the Aleutian subduction zone. At this point on the earth’s surface, the Pacific tectonic plate is being subsumed below the crust to the north, a zone where stress builds up and is released as earthquakes. No damage had been reported at the time of writing.
In the past earthquakes in Alaska have been responsible for tsunamis, some of which have caused significant damage and loss of life in the Pacific islands and along the North America’s Pacific coast. Though the September 3 earthquake was significant, no tsunami warning was issued, although it was possible that some areas could experience what were described as ‘non-damaging sea level changes’ (NOAA West Coast and Alaska Tsunami Warning Center, “Tsunami Information Statement”).
Recent Seismic Events in Alaska
The Aleutian Islands lie on Pacific Rim and, as a consequence of the geological setting, are regularly shaken by earthquake activity. The subduction of the Pacific Plate also generates extensive volcanic activity: the Smithsonian Institute’s Global Volcanism Program lists 40 volcanoes in the island chain (Smithsonian Institute, “Volcanoes of Alaska”).
A study of the USGS data listings indicates that minor earthquakes are extremely common in the Aleutians: USGS data show that over 80 earthquakes of greater than magnitude 2.5 occurred in the island chain between 10th and 27th August 2010, the majority in the Fox Islands. Other earthquakes occurred elsewhere in Alaska, though these were fewer in number (USGS).
The pattern of seismicity displayed along the Aleutians is one of regular small earthquakes punctuated by occasional larger ones and, very rarely, major events. The September 2010 event follows relatively soon after the previous large earthquake to strike the Aleutians, the 6.1M (initially reported as 6.7) event which occurred on 17 July 2010, some way to the west in the Fox Islands. Prior to that event, the last significant earthquake event recorded was a magnitude 6.6 which occurred in April 2008.
Read more at Suite101: Second Large Earthquake in Two Months Strikes Aleutian Islands http://www.suite101.com/content/second-large-earthquake-in-two-months-strikes-aleutian-islands-a281905#ixzz0yUjtq5lt
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