<P> Lasting four minutes and thirty - eight seconds , the magnitude 9.2 megathrust earthquake was the most powerful recorded in North American history , and the second most powerful recorded in world history . Soil liquefaction , fissures , landslides , and other ground failures caused major structural damage in several communities and much damage to property . Anchorage sustained great destruction or damage to many inadequately earthquake engineered houses , buildings , and infrastructure ( paved streets , sidewalks , water and sewer mains , electrical systems , and other man - made equipment ) , particularly in the several landslide zones along Knik Arm . Two hundred miles southwest , some areas near Kodiak were permanently raised by 30 feet ( 9.1 m ) . Southeast of Anchorage , areas around the head of Turnagain Arm near Girdwood and Portage dropped as much as 8 feet ( 2.4 m ) , requiring reconstruction and fill to raise the Seward Highway above the new high tide mark . </P>
<P> Lasting four minutes and thirty - eight seconds , the magnitude 9.2 megathrust earthquake was the most powerful recorded in North American history , and the second most powerful recorded in world history . Soil liquefaction , fissures , landslides , and other ground failures caused major structural damage in several communities and much damage to property . Anchorage sustained great destruction or damage to many inadequately earthquake engineered houses , buildings , and infrastructure ( paved streets , sidewalks , water and sewer mains , electrical systems , and other man - made equipment ) , particularly in the several landslide zones along Knik Arm . Two hundred miles southwest , some areas near Kodiak were permanently raised by 30 feet ( 9.1 m ) . Southeast of Anchorage , areas around the head of Turnagain Arm near Girdwood and Portage dropped as much as 8 feet ( 2.4 m ) , requiring reconstruction and fill to raise the Seward Highway above the new high tide mark . </P>
what was the magnitude of the 1964 alaska earthquake
what was the magnitude of the 1964 alaska earthquake
9.2 megathrust
9.2 megathrust