Tectonic earthquakes and Alaska volcanoes
Posted: November 30, 2018
Seismic station at Great Sitkin
Large tectonic earthquakes rarely trigger volcanic eruptions; this is an active area of research, but there are only a few convincing cases globally, and those are most likely to occur at volcanoes already in eruption or primed to erupt.
• The current eruptive activity at Veniaminof, and the unrest at Cleveland, Semisopochnoi, and Great Sitkin, continues without change since this morning's large tectonic earthquake.
• AVO maintains ground-based networks for seismic and GPS monitoring of Alaska volcanoes, along with remote sensing methods such as satellite and infrasound.
• AVO’s volcano-monitoring networks also record tectonic earthquakes, and broaden the data set of all types of earthquakes, such as the tectonic earthquake experienced on the morning of 30 November 2018.
The M7.0 earthquake was tectonic and not volcanic:
• For more information about this tectonic earthquake, please visit the National Earthquake Information Center: https://earthquake.usgs.gov/earthquakes/eventpage/us1000hyfh/oaf/commentary
or the Alaska Earthquake Center: https://earthquake.alaska.edu/anchorage-m70-what-we-know-so-far
• The earthquake occurred at a depth of 24 miles beneath the surface (40 km).
• The earthquake occurred in the subduction zone - the interface between the Pacific and North America plates, which extends to depths of 24 to 37 miles (40 to 60 km).
• Subduction zones, where most active volcanoes are found, can generate high rates of earthquakes that are not volcanic.
• Aftershocks will occur.
• The Aleutian arc is a seismically active region, evidenced by the many moderate to large earthquakes occurring each year. Since 1900, this region has hosted twelve large earthquakes (M>7.5) including the May 7, 1986 M8.0 Andreanof Islands, The June 10, 1996 M7.9 Andreanof Islands, and the November 17, 2003 M7.8 Rat Islands earthquakes.
• The most recent large earthquake to occur in this area was the 2016 M7.1 Iniskin earthquake.
Links for further information:
USGS National Earthquake Information Center earthquake information: https://earthquake.usgs.gov/
Alaska Earthquake Center earthquake information: http://earthquake.alaska.edu/
NOAA tsunami information: https://www.tsunami.gov/
Earthquake preparedness information: https://www.muni.org/Departments/OEM/Prepared/Pages/EarthquakePrep.aspx
Alaska Volcano Observatory information statements and volcano status updates: https://avo.alaska.edu