The 1904Ms 7.3 Earthquake in Central Alaska

Abstract

Abstract On 27 August 1904, seismic stations from around the globe recorded an M >7 earthquake originating from central Alaska. Very little was known about this earthquake. One felt report from Rampart, Alaska, had been attributed to the notes of Harry Fielding Reid, yet its original source was unknown. Here, we present five felt reports for the 1904 earthquake that show evidence of felt shaking across most of central Alaska. Using the 1904 arrival‐time data, we estimate an epicentral location near Lake Minchumina at the northeastern extent of the Iditarod–Nixon fault. Our preferred fault for the 1904 earthquake is the right‐lateral Iditarod–Nixon fault, which, though relatively seismically quiet, generated an M 6.2 earthquake in 1935. Paleoseismic investigations are needed to search for evidence of fault activity, including the 1904 earthquake rupture, in the tectonically complex region of the 1904 earthquake. Electronic Supplement: Tables of arrival time, figures of station registers, visualization of NonLinLoc (NLL) solution for the 1904 Alaska earthquake, distribution of depths of the posterior probability for the 1904 and 1935 events, epicenter and samples of the posterior probability distribution for the 1904 and 1935 earthquakes, map of southward shift of epicenters, and estimated epicenters for the 3 February 2000 Kaltag earthquake.