Physical Sciences and Mathematics Commons^™

Extent And Duration Of The 2003 Cascadia Slow Earthquake, Walter Szeliga, Timothy I. Melbourne, M. Meghan Miller, Victor Marcelo Santillan

Faculty Scholarship for the Cascadia Hazards Institute

Inversion of continuous GPS measurements from the Pacific Northwest show the 2003 Cascadia slow earthquake to be among the largest of ten transients recognized here. Twelve stations bracketing slow slip indicate transient slip propagated bi-directionally from initiation in the southern Puget basin, reaching 300 km along-strike over a period of seven weeks. This event produced, for the first time, resolvable vertical subsidence, and horizontal displacement reaching six mm in southern Washington State. Inverted for non-negative thrust slip, a maximum of 3.8 cm of slip is inferred, centered at 28 km depth near the sharp arch in the subducting Juan de …