San Francisco and Oakland were rocked after a section of the San Andreas fault located around Santa Cruz, Calif., ruptured over a 45 kilometer stretch. The force of the temblor reminded the country - and even San Francisco old timers - about the risks of building in an earthquake zone. And while it may have been the first such quake in most Americans' memories, it had antecedents going back to the 19th century. After the recent tragedy in Japan, is complacency still an option? If past is prologue, the answer may be one we won't like very much.
San Francisco after the earthquake of 1868On October 21, 1868, San Francisco was rocked by an earthquake with a magnitude of 7.0. At the time, about 260,000 people lived in the Bay Area. The earthquake, felt throughout the northern part of the state and Nevada, left five people dead and 30 injured. Damage was estimated at $300,000.
Following the quake, one conclusion reached by engineers was to avoid erecting buildings on land reclaimed from San Francisco bay. Unfortunately, that concern was quickly forgotten as the city rapidly rebuilt - with tragic results in 1906.
Flour mill & warehouse, Hayward, Calif. after the 1868 earthquakeThe next day, the San Francisco Morning Call recounted how the city "was visited by the most severe earthquake" residents had ever experienced.
"The great shock commenced at 7:53 A.M. and continued nearly one minute, being the longest ever known in this region. The oscillations were from east to west, and were very violent. Men, women, and children rushed into the streets--some in a state of semi-nudity--and all in the wildest state of excitement. Many acted as if they though the Day of Judgment had come. for a time the excitement was intense, and the panic was general."
You can read the entire dispatch here.
Harper's Weekly, 1868Since 1800, 21 earthquakes with a magnitude of 6.0 or greater have hit San Francisco area (Six of them have registered between 6.5 and 7.0.)
Hayward, California after the 1868 quakeThe Hayward Fault runs through the San Francisco suburb of Hayward, California. During the 1868 earthquake, the southern end of the fault ruptured, sending seismic shock waves throughout the region.
Active traces of the Hayward FaultPeriodic movements in the Hayward Fault have jolted the region for decades. According to the USGS, scientists consider the fault to be a tectonic time bomb, one likely to generate earthquakes in the 7.0 range.
Fire during 1906 San Francisco earthquakeThe 1906 San Francisco earthquake is estimated to have been in the 7.8 range (and possibly even larger.) Like the Loma Prieta earthquake of 1989, the San Andreas Fault was responsible for the 1906 temblor. More than 3,000 people died due to a combination of the earthquake and resulting fire. At the time, the area had a population of 400,000 people.
Deep cracks left by the 1906 quakeSan Francisco after the 1906 earthquake. The image shows a fissure in the road at Eighteenth and Folsom streets.
Building left destroyed by 1906 earthquake
San Andreas FaultThis photograph taken 1908 shows the surface rupture along the San Andreas fault near Point Reyes Station, north of San Francisco.
The fault represents the classic boundary between the North American and Pacific Plates.
The San Francisco bay area sits along major fault lines and thus runs the risk of suffering devastating consequences should it ever get hit by a monster-sized earthquake. But the problem isn't necessarily that earthquakes are increasing in frequency or size. In fact, says Colin Stark, Lamont Associate Research Professor at the Lamont-Doherty Earth Observatory of Columbia University, the problem is that we prefer to keep believing the dice will fall in our favor and so we keep building. "Megacities across the world continue to grow, and many are along major faults. Most of these faults have not generated giant earthquakes in recent memory, but historical and geological records, supported by abundant geophysical data, show they do so every few hundred years," he wrote in an op-ed piece for CNN.com.