Constraints on the Slip Distribution of the 1938 MW 8.3 Alaska Peninsula
Earthquake from Tsunami Modeling
We simulated tsunami propagation for several scenario slip distributions
for the 1938 MW 8.3 earthquake along the Alaska
Peninsula, and compared these to the observed records at Unalaska/Dutch
Harbor and Sitka. The Sitka record is sensitive to the depth of slip but
not the along-strike location, and is fit best by slip at shallow depth.
The Unalaska record is sensitive mainly to the along-strike location of
slip, and is fit best by slip that is concentrated in the eastern part
of the presumed 1938 rupture zone. The tsunami data show that the actual
1938 earthquake rupture zone was smaller than previously thought, likely
~200 km in length, and had no slip near the Shumagin
Islands or in the 2020 Simeonof earthquake’s rupture zone. The rupture
models that best predict the 1938 tsunami lie within the region of high
present day slip deficit inferred from GPS.