Quick Quake Briefing Webinar: M7 Alaska Hubbard Glacier Earthquake

Value of the Information & Strength of the Argument

The webinar provides valuable insights into a significant seismic event in a remote region. The speakers present a clear narrative linking the earthquake to the broader tectonic framework, using evidence from geodesy, historical seismicity, and aftershock patterns. The argumentation is solid, with each point supported by data and references to published studies. The discussion of the connector fault is particularly valuable, as it fills a gap in understanding the regional fault system. The presentation of USGS real-time products demonstrates the practical application of seismological research for rapid hazard assessment. The speakers are careful to distinguish between established facts and preliminary interpretations, such as the stress transfer models, which are described as ‘work in progress.’ Overall, the information is well-structured and scientifically rigorous.

Scientific Rigor, Source Quality, Title Accuracy

The webinar maintains high scientific rigor. The speakers are leading experts in their fields, and the content is consistent with current seismological knowledge. They reference several published studies, including those by Elliott and Freymueller (on tectonic block motions) and the USGS seismic hazard model for Alaska. The use of official data from the Alaska Earthquake Center and USGS adds credibility. The title accurately reflects the content, and the webinar is well-organized. The presence of a brief sponsorship segment for EERI members is noted but does not detract from the scientific value. The Q&A session further clarifies technical points, demonstrating the speakers’ depth of knowledge. Overall, the sources are reliable and the presentation is trustworthy.

The title accurately reflects the content: a briefing on the M7 Alaska Hubbard Glacier earthquake, covering seismology and ground failure.

8/10

The webinar features two authoritative speakers: the Alaska State Seismologist and a USGS research geophysicist specializing in earthquake-induced landslides. They present data from official monitoring networks and reconnaissance flights, and the content is consistent with established seismological and geological knowledge. However, the webinar is a briefing rather than a peer-reviewed study, and some interpretations are preliminary.

Markers derived by PSI from the transcript: the creator did not define chapters.

• 02:00Introduction by Maggie Ortiz Milan, EERI Director of Programs, and welcome from Dick McCarthy, President of the Northern California Chapter.
• 05:00Bruce Mason introduces the webinar format and the two speakers.
• 10:00Dr. Michael West begins his presentation on the seismology of the earthquake, starting with the tectonic setting of the Fairweather Fault.
• 20:00West discusses the Yakutat block and its role in driving regional tectonics, referencing the 2002 Denali Fault earthquake.
• 30:00West explains the inferred connector fault and how the earthquake's location and focal mechanism support its existence.
• 40:00West shows aftershock distributions and stress transfer models, highlighting ongoing research.
• 50:00West discusses ground motion records and the importance of long-period shaking for triggering landslides.
• 1:00:00Dr. Kate Allstadt begins her presentation on landslides and avalanches, describing USGS real-time products.
• 1:10:00Allstadt shows reconnaissance photos and discusses the over 700 landslides triggered, with some traveling over 3 miles.
• 1:20:00Q&A session begins, with questions from the audience addressed by both speakers.

• EERI Website — Mentioned as the organization hosting the webinar and providing resources.
• USGS Earthquake Hazards Program — Referenced for ShakeMap, PAGER, and ground failure products.
• Alaska Earthquake Center — Referenced as the source of seismic data and aftershock monitoring.
• Yukon Geological Survey — Mentioned as a collaborator for reconnaissance flights and field assessment.

• Elliott, J. L., & Freymueller, J. T. (2020). A Block Model of Present-Day Kinematics of Alaska and Western Canada. Journal of Geophysical Research: Solid Earth. — Referenced by Dr. West for the tectonic block model showing the rotation of southern Alaska.
• USGS National Seismic Hazard Model for Alaska (2023) — Referenced as the source of the fault set used in the seismic hazard map.