On March 22, 1957 an earthquake struck San Francisco. At a magnitude of 5.7 its epicenter was just off the San Francisco Peninsula near the San Andreas Fault. It was felt in portions of Northern and Central California. The most significant effects were seen in the western portion of Daly City and in the Lake Merced area of San Francisco. Hence this quake was also referred to as the Daly City Quake of 1957.
Structural losses cost about $1 million and were considered minimal. Damage was primarily to content within buildings and cracked plaster. The minimal losses were attributed to the short duration and lack of high intensity shaking. However, one death and forty injuries were attributed to the event.
As shown on the following three pages, Water Department management tallied various elements of service affected due to the quake, including incoming service calls, in-city pipes and valves, and an interesting array of “miscellaneous damage.” The latter including a chimney, slippage of banks around Lake Merced, and settled landfill causing pipe severance.
Reservoirs seemed to come through fairly well, with the most predominant evidence of damage being spalling (fragments of solid material having sheared off). Sutro Reservoir seemed to have revealed the most evidence of the earthquake. Interestingly, this reservoir had been drained and inspected, and “underdrain” leakage measured just prior to the earthquake. Therefore, observation of leakage was possible following the quake, but leakage was reduced within days and leveled off satisfactorily according to the report.
And finally looking at the situation outside of the City, the report turns to the situation in the Peninsula Division and the Alameda Division. This section starts out with “Trouble at the Airport,” reporting on cracked pipes at the terminal building.
Peninsula cottage inventory showed broken china, damaged chimney, cracked plaster, broken window, etc. But the dams (San Andreas and Crystal Springs) came though unscathed. Some pipe pressure surges were registered, and some leaking pipes also occurred on the peninsula. Alameda Division came through pretty well.
And finally, the assessment of Headquarters – mostly cracks – internal and external. Some spalling in room 707 (the worst hit) “however, it was an old crack made worse.” And the best part of this tally: “these cracks do not indicate any particular structural damage.” Minimal impacts indeed.