USGS Near-Real-Time Ground Failure Product for the 2018 Anchorage Earthquake

Date: 4/26/2019

Time: 11:30 AM

Room: Cascade II

The 2018 M7 Anchorage, Alaska, earthquake is the first earthquake to cause significant damage in the United States since the U.S. Geological Survey (USGS) began providing ground failure hazard information on the earthquake event webpages in May of 2018. These automated ground failure reports provide qualitative alert levels and quantitative summary information. The quantitative information includes aggregate hazard and population exposure statistics for earthquake-induced landslides and liquefaction, as well as maps of the locations of highest probable hazard. The Anchorage earthquake provides a timely, critical test of the accuracy, design, and utility of the ground failure product. To assess model accuracy, we documented the presence or absence of liquefaction and landsliding in the field, targeting zones of both high and low hazard as predicted by the ground failure models. The modeled distributions of landslide and liquefaction hazards, however, did not perfectly match the observed pattern of ground deformation. We primarily observed liquefaction in areas of moderate to high modeled hazard (e.g., Matanuska Valley) while also noting the absence of evidence for liquefaction in some high-hazard zones (e.g., Chickaloon Bay). The landslide model correctly identified heightened hazard in the Chugach Mountains, but did not identify the hazard on coastal bluffs. The observations of ground failure in this earthquake will be used to improve the existing models and in the development of new models. We also summarize how the product was covered by the media and how communication and product usefulness can be improved in the future. Both media reports and USGS field observations generally support the alert statements automatically issued following the earthquake.

Presenting Author: Eric M. Thompson

Authors