San Francisco Bay Region Landslides

On this day in 1982, a series of landslides near San Francisco, California, kills up to 33 people and closes the Golden Gate Bridge.

In all, an amazing 18,000 different landslides took place in the San Francisco Bay Area following a very heavy rain storm.

Two fast-moving fronts carrying extremely heavy rain passed through San Francisco in a 36-hour period beginning on January 4, during which the area received an amount of rain equal to half its average annual precipitation. Some areas received as much as 24 inches of rain on January 4 and 5. On January 5, the rain began to trigger thousands of separate landslides in the Bay Area hills.

Most rainstorms are of such low intensity that they do not trigger debris avalanches. Some intense storms may trigger only a few debris avalanches. However, when the ground is already saturated from previous rain, even relatively short high-intensity rainstorms may trigger debris avalanches. For example, in January 1982, an intense rainstorm triggered literally tens of thousands of debris avalanches in the San Francisco Bay Area. These 1982 debris avalanches caught people unaware and caused 14 deaths and many injuries and destroyed or damaged several hundred homes and other structures.

A catastrophic rainstorm in central California on January 3-5,1982, dropped as much as half the mean annual precipitation within a period of about 32 hours, triggering landslides and floods throughout 10 counties in the vicinity of the San Francisco Bay. More than 18,000 of the slides induced by the storm transformed into debris flows that swept down hillslopes or drainages with little warning. Debris flows damaged at least 100 homes, killed 14 residents, and carried a 15th victim into a creek. Shortly after rainfall ceased, more than 459,000 m3 of earth and rock slid from a mountainside above the community of Love Creek in Santa Cruz County, burying 10 people in their homes. Throughout the bay region, thousands of people vacated homes in hazardous areas, entire communities were isolated as roads were blocked, public water systems were destroyed, and power and telephone services were disrupted. Altogether, the storm damaged 6,300 homes, 1,500 businesses, and tens of kilometers of roads, bridges, and communication lines. Preliminary rough estimates of total storm damage, compiled for emergency purposes within 2 weeks of the storm, exceeded $280 million. Carefully documented direct costs from landslides exceeded $66 million; total costs from landslides certainly were greater and probably constituted a much larger proportion of the total storm damage than suggested by these disparate figures. Landslides accounted for 25 of the 33 deaths attributed to the storm.

5th January, 1982 : A tragic landslide occurrence took place near San Francisco. It had killed 33 people, and had caused the closing of the Golden Gate Bridge.

Before this landslide took place, heavy rain fell for about 36 hours straight. Just from this one rainfall, San Francisco had received about half of its average annual precipitation.