How Large Must an Earthquake be to Trigger Landslides?
A possible trigger for a landslide that might generate dangerous waves would be ground shaking during an earthquake on the WKLFZ, especially the Annie Spring and Red Cone Spring faults. In order to cause a wave, the avalanche or slide must travel rapidly into or beneath the lake. There are many types of “landslides” that may be triggered by earthquake shaking. Those considered possible at Crater Lake include disrupted falls, slides, and avalanches of rock, soil (broadly defined as a loose, unconsolidated, or poorly cemented aggregate of particles), or snow and coherent slumps and block slides (as defined by Keefer, 1984). Subaqueous slides are likely to consist of the same kinds of rock or soil as in subaerial slides, rather than sand or finer-grained sediments, so that we will not differentiate between the two environments for purposes of this report. Moreover, because we are concerned with falls and slides that may displace sufficient lake water to cause damaging waves, we only consi
