Triggering of mass-wasting events
A mass-wasting event can occur any time a slope becomes unstable. Sometimes, as in the case of creep or solifluction, the slope is unstable all of the time, and the process is continuous. But other times, triggering events can occur that cause a sudden instability to occur.
A sudden shock, such as an earthquake may trigger a slope instability. Minor shocks like heavy trucks rambling down the road, trees blowing in the wind, or man made explosions can also trigger mass-wasting events.
Modification of slope either by humans or by natural causes can result in changing the slope angle so that it is no longer at the angle of repose. A mass-wasting event can then restore the slope to its angle of repose.
Heavy rains can saturate regolith reducing grain to grain contact and reducing the angle of repose, thus triggering a mass-wasting event.
produce shocks like explosions and earthquakes. They can also cause snow to melt or empty crater lakes, rapidly releasing large amounts of water that can be mixed with regolith to reduce grain to grain contact and result in debris flows, mudflows, and landslides.
Submarine Slope Failures
These can be caused by rapid deposition of sediment that does not allow water trapped between grains to escape, or by generation of methane gas from the decay of organic material, which increases pressure between unconsolidated grains and thus reduces grain to grain contact.