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Earthquake Hazards Program

#### U.S. Geological Survey Professional Paper 993

# Historic Ground Failures in Northern California Triggered by Earthquakes

### *By*T.L. Youd and S.N. Hoose

### 1978

Map of California showing Coast Ranges province, areas covered by regional maps, and areas in which ground failures have occurred during historic northern California earthquakes**

#### Abstract

A major source of earthquake-related damage and casualties in northern California has been ground failures generated by the seismic shaking, including landslides, lateral spreads, ground settlement, and surface cracks. The historical record shows that, except for offshore shocks, the geographic area affected and the quantity and general severity of ground failures increase markedly with Richter magnitude. Hence, the largest historical event, the 1906 San Francisco earthquake, has been the most important generator of ground failures. Because of recent population growth and land development in northern California, the potential for damage in future events is enormous compared with that existing in 1906. 

Reports of the 1906 San Francisco earthquake and other northern California earthquakes and descriptions of ground failures therein are used to (1) identify and clarify the types of ground failures associated with earthquakes, (2) provide a guide for engineers, planners, and others responsible for minimizing seismic hazards, and (3) form a data base for other geotechnical studies of earthquake-triggered pound failures. 

Geologic, hydrologic, and topographic setting have an important influence on ground failure development as well as distance from the causative fault. Areas especially vulnerable to ground failure in northern California have been oversteepened slopes, such as mountain cliffs, streambanks, and coastal bluffs, and lowland deposits, principally Holocene fluvial deposits, deltaic deposits, and poorly compacted fills. Liquefaction has been the direct cause of most lowland failures. The historical record suggests that ground failures during future large earthquakes are most likely to occur at the same or geologically similar locations as failures during previous earhquakes.

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#### Text

Download the text of this report as a 180-page PDF file (pp993_text.pdf; 8 MB).

#### Photographs

The text linked above was made by scanning printed pages in black and white.  Pages that have photographs do not show the shades of gray.  So we acquired nice gray-scale scans of the photographs used in the figures and provided them in the folder linked below.  The files range from 250 kB (1.2 megapixels) to 13 MB (23 megapixels).  Most in the 2–6-MB range.
Go to the print-resolution Photographs folder that contains 70 JPG files (278 MB total).

Go to the web-resolution Photographs folder that contains the same 70 photos but downsampled for viewing with your browser (8.9 MB total).
Plates
Download Plate 1 as a ~34" x ~21" PDF file:  Location Map of Ground Failures in the Monterey Bay Counties Region (pp993_plate1.pdf; 8.1 MB).

Download Plate 2 as a ~29" x ~21" PDF file:  Location Map of Ground Failures in the San Francisco Bay Counties Region (pp993_plate2.pdf; 5.4 MB).

Download Plate 3 as a ~27" x ~27" PDF file:  Location Map of Ground Failures in San Francisco City and County (pp993_plate3.pdf; 7.8 MB).

Download Plate 4 as a ~33" x ~21" PDF file:  Location Map of Ground Failures in the North Bay Counties Region (pp993_plate4.pdf; 9.2 MB).

Download Plate 5 as a ~16" x ~22" PDF file:  Location Map of Ground Failures in the North Coast Counties Region (pp993_plate5.pdf; 54.3 MB).
Also of Interest
From the Loma Prieta Earthquake Professional Papers, see also:  USGS Professional Papers 1551-A, B, C, D, and F,  *Strong Ground Motion and Ground Failure*, Coordinated by Thomas L. Holzer

For questions about this report, contact Les Youd (Brigham Young University).

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U.S. Department of the Interior | U.S. Geological Survey URL: https://pubs.usgs.gov/pp/1978/pp0993/ Page Contact Information: Michael Diggles Page Last Modified: October 2, 2008 (mfd)