During 2019-2020, the Alaska Earthquake Center underwent an unprecedented expansion of our permanent seismic monitoring network. We were able to achieve it by acquiring 96 of 158 temporary USArray sites in Alaska.
This evening’s M7.8 earthquake [7/21/20, 10:12 PM AKDT] occurred on the well-known subduction zone interface off the Alaska Peninsula. Strong shaking has been reported from Perryville and Sand Point to King Cove and Cold Bay.
We use the phrase “magnitude of completeness” often when referring to our understanding of seismicity in a region or following a sequence of earthquakes. This value is a simplistic assessment of a catalog of earthquakes.