Slip on the Suckling Hills splay fault during the 1964 Alaska earthquake

The Suckling Hills in southern Alaska experienced localized, anomalously large coseismic uplift in the Mw 9.2, 1964 Alaska earthquake. Large uplift at the Suckling Hills can be explained by increased slip, or an asperity, on the Alaska-Aleutian megathrust; however, this paper suggests that increased uplift may be a result of slip on the Suckling Hills splay fault. We present a series of models that demonstrate how the inclusion of the Suckling Hills fault improves the fit between modeled vertical displacement and measured coseismic uplift in comparison to slip on the Alaska-Aleutian megathrust alone. Our results suggest that ~3m of average slip on the Suckling Hills fault during the 1964 earthquake can help explain the large coseismic uplift data. These results are consistent with recent studies indicating Pleistocene slip on the Suckling Hills fault and together highlight the potential seismic and tsunami risk associated with this segment of the Alaskan subduction complex. •Suckling Hills splay fault likely slipped ~3m in the 1964 Alaska Earthquake.•No significant asperity on the megathrust beneath the Suckling Hills•Simplified map pattern of maximum coseismic uplift