3.12 Amchitka section
The Amchitka section (Figure 6) extends ~325 km from Amchitka Pass to Murray Canyon and encompasses the eastern portion of the Mw 8.7 1965 Rat Islands rupture, as well as the area of the much smaller 2003 Mw 7.8 earthquake (Figure 1). The Amchitka section corresponds to the hypothesized Rat structural block of (Geist et al., 1988) and one of three asperities in the 1965 event proposed by Beck & Christensen (1991).
Geodetic observations in the Amchitka section are sparse (Cross & Freymueller, 2008) and no direct coupling model is available. Based on the neighboring Attu section, we infer 50% coupling over an area roughly the same as the Attu section, extending ~115 km arcward from the deformation front to approximately 40 km interface depth (Figure 6).