Final answer:
The 1964 lateral spread slide in Turnagain Heights, Anchorage, Alaska was triggered by an earthquake.
Step-by-step explanation:
The 1964 lateral spread slide in Turnagain Heights, Anchorage, Alaska was triggered by earthquake. An earthquake occurred in the area, which caused the ground to shake and destabilize, resulting in the lateral movement of the earth and the subsequent slide. The earthquake was part of a larger seismic event that was related to the tectonic plate movement in the area.