Images

Comparison of (a) pre- and (b) post-event satellite images showing the source area of the August 10th landslide that impacted Tracy Arm. The dashed line in (a) shows the approximate location of the front of South Sawyer Glacier on August 7th, 2025 (mapped from imagery © 2025 Planet Labs PBC).

Oblique aerial photo of the August 10, 2025 landslide taken from across the fiord during a field reconnaissance overflight on August 13, 2025. Look direction is approximately north.​

Oblique aerial photo of the August 10, 2025 landslide source area captured during a field reconnaissance overflight on August 13, 2025. Look direction is approximately north.​

Oblique aerial photo of Sawyer Island captured during a field reconnaissance overflight on August 13, 2025. Look direction is to the southeast.​

Oblique aerial photo of the August 10, 2025 landslide captured during a field reconnaissance overflight on August 13, 2025. Look direction is to the west.​

Photo of tsunami-inundated shoreline at Williams Cove, near the mouth of Tracy Arm. Look direction is approximately north.​

Oblique aerial photo of the August 10, 2025 landslide headscarp. Look direction is to the northwest.​

USGS Rob Anthony sets up equipment in a freezer to test a Seismometer Interface Module at the Physical Sciences Laboratory in Stoughton, Wisconsin on Aug. 7, 2025. (Photo by Taylor Wolfram / UW–Madison)

Nicholas Pelyk, Jason Patton, Rob Anthony, and Skyler Grulke slide a part into the tube while assembling a seismometer at the Physical Sciences Laboratory in Stoughton, Wisconsin on Aug. 7, 2025. (Photo by Taylor Wolfram / UW–Madison)

Jason Patton, Rob Anthony (USGS), and Skyler Grulke assemble a seismometer at the Physical Sciences Laboratory in Stoughton, Wisconsin on Aug. 7, 2025. (Photo by Taylor Wolfram / UW–Madison)

USGS Rob Anthony puts in the Seismometer Interface Module while assembling a seismometer at the Physical Sciences Laboratory in Stoughton, Wisconsin on Aug. 7, 2025. (Photo by Taylor Wolfram / UW–Madison)

Map of the United States and its territories showing the distribution of average annualized earthquake losses by region (modified from Jaiswal and others, 2023). Economic losses from earthquakes in these nine regions are estimated to average \$14.7 billion dollars per year.

Map of the United States and its territories showing 2024 International Building Code Seismic Design Categories and Risk Categories.

An example of Bayesian updating of productivity parameter (a-value) for the 2010 Mw 8.8 Maule, Chile, earthquake. Immediately following the earthquake, the SZ-GENERIC region-specific a-value distribution can be used.

Screenshot of the Aftershock Forecast for an earthquake in California, showing the information box at the top of the forecast and the four tabs of forecast information.

Aftershock Forecast Sequence-Specific Model Parameters equation 

The probability distribution for the number of aftershocks, P(N), and the forecast can then be computed using the same procedures as for the generic model, using P_seq-spec(a) instead of P_generic(a).

Screenshot of the Aftershock Forecast for an earthquake in California, with the “Summary” tab selected, and “M4+” and “Show All” selections for magnitude and forecast duration.

Screenshot of the Aftershock Forecast for an earthquake in California, with the “Forecast Table” tab selected.

Screenshot of the Aftershock Forecast for an earthquake in California, with the “Summary” tab selected, and “M4+” and “Show All” selections for magnitude and forecast duration.
 

Screenshot of the Overview webpage for an earthquake in California. The “Aftershock Forecast” card is at lower center.

Screenshot of the Aftershock Forecast for an earthquake in California, with the “Summary” tab selected, and “Show All” and “1 Month” selections for magnitude and forecast duration.