New Years Day Flood
January 01, 2002
January 1 in southern California is usually associated with the Pasadena Rose Parade and Rose Bowl game. But it also marks the anniversary of the "New Year's Day Flood" of 1934 in the nearby La Cañada Valley. The flood killed more than 40 people, destroyed about 400 houses, and damaged streets, bridges, and highways.
About 7.5 square miles of mountain area adjacent to the La Cañada Valley were burned over by a fire in November, 1933. Fire increases the likelihood of landslides after a heavy rain by destroying the vegetation that anchors top soil, which makes it more likely that the soil will slide when saturated. Winter storms of 1933/34 produced the heaviest rainfall in years. Sediments of all sizes - including boulders weighing tons - had been building up in the canyons for a long time. The heavy rains and the burned hills caused the debris to flow, and destroy all in its path. Catchment basins and flood control dams have since been built to help contain debris flowing from the mountains, but the awesome power of water on the alluvial slopes of the San Gabriels is a threat that will remain well into the geologic future.
This Landsat 7 image was acquired in December, 2000 and depicts vegetation as red and urbanized areas as blue.