Tectonic position in the interior of Alaska

Seismicity in interior Alaska reflects transpression and block rotation. Three different types of tectonic structures contribute to the generation of seismicity in this region: right-lateral strike-slip faults (Denali, Tintina, Kaltag), north-northeast trending seismic zones (Minto, Fairbanks, Salcha, Dall City, Rampart), and thrust faults in the northern foothills of the Alaska Range. The largest event recorded in the interior was the magnitude 7.3 Salcha earthquake in 1937. It caused extensive ground collapse at the epicenter, but there was no documented evidence of surface rupture. Other notable events include the magnitude 7.1 Rampart earthquake in 1968, the magnitude 6.1 Dall City earthquake in 1985, and the magnitude 6.0 Minto Flats earthquake in 1995. Three magnitude 5-6 earthquakes occurred in the Fairbanks Seismic Zone in 1967. A magnitude 7.2 thrust event occurred in 1947 on the leading edge of the northern foothills of the Alaska Range and south of the Salcha Seismic Zone. This event, together with current seismic activity, is indicative of ongoing thrust deformation on the north side of the central Alaska Range. East of 146°W longitude, seismic activity decreases considerably between the Tintina Fault to the north and the Denali Fault to the south.