La Conchita, landslide and earthflow occurred spring of 1995 in coastal area of southern California. People were evacuated and the houses nearest the slide were completely destroyed.

Landslides in the United States cause approximately $3.5 billion (year 2001 dollars) in damage, and kill between 25 and 50 people annually. Casualties in the United States are primarily caused by rockfalls rock slides debris flows.

(USGS)

fast

Topple Rock fall Rock slide

0 % water 20

Debris avalanche Earth flow Soil creep

GRANULAR

Debris avalanche

Slope saturation by water is a primary cause of landslides.

Ve

loci

ty

20 % water 40

Debris flow

SLURRY

Debris flow type of alluvial fan along the Santa Rosa Mountains, San Diego County, Calif. Debris flows emerging from the top of the fan at the entrance of the canyon form a typical cone-shaped fan with many channels, and boulder strewn fields.

debris flow

Debris flow deposit typically with oversized clasts "floating" in a mud-rich matrix. Coffin Canyon Fan, Death

Valley, California.

mud flow

slow Slump

Earth flow

Earth flow

soil creep

Soil creep

solifluction