A building in downtown San Francisco damaged in the 1906 quake. City Hall the day before the earthquake. Damage on East Howard Street after the 1906 earthquake. Damage to the Embarcadero area, a result of the 1906 quake in San Francisco. Damage to City Hall after the earthquake occurred. Wood houses were thought to have fared quite well during this earthquake; however, this one in particular was stationed in the Marina district of San Francisco.

1906 San Francisco Earthquake On April 18th, 1906 at 5:12 am, a very large earthquake struck the San Francisco Bay Area. As a result, buildings were destroyed, hundreds were killed, and electrical, gas, and water mains were ruptured. Severed water mains resulted in a wildly-burning conflagration which lasted for days in a residential and business district of San Francisco, south of Market Street. This map displays the areas that were affected by the 1906 earthquake. It affected areas as far north as Healdsburg and Santa Rosa, and as far south as Salinas. A 270-mile stretch of the San Andreas fault ruptured that day, with the largest displacement (separation of land horizontally) being 21 feet, to the northwest of San Francisco. The earthquake was an M7.7 on the moment magnitude scale (an 8.3 on the Richter scale), the 6th largest earthquake to occur in the contiguous United States. More that 3,000 casualties were reported in San Francisco, the population at that time a mere 400,000. Over half the entire population of San Francisco was left homeless, mostly due to the continuous 3-day fire that destroyed nearly 5 square miles of both businesses and private homes. Almost 30,000 buildings were destroyed, and the area lost a total of about $400 million. This was the largest offset caused by the earthquake, 21 feet. It happened northwest of San Francisco, at Point Reyes. Much of the damage was initially most severe in the Marina district, where buildings had foundations consisting of bayfill and sand. Bayfill often magnifies the shaking during an earthquake, which can cause an M6.0 to emulate the damage of an M7.0. The shaking of the buildings lasted a few seconds longer than the original shockwaves, contributing to the bad condition of the Marina district. However, it is thought by many that the fire caused most of the property damage as a result of the earthquake. Many buildings burned during the inferno, and because of a lack of working water mains, the fire department was almost powerless to stop the fire. They eventually had to resort to extreme measures: creating a fire block with the surrounding houses. The method worked, and after 3 days of an incessant blaze, the fire was finally out. It is thought that the fire caused most of the property damage as a result of the earthquake. It burned for 3 days, destroying nearly 5 sq. mi. of San Francisco land. The reason for the water main problems stems from the Marina district's many woes. The water mains were located within the bayfill, and as a result, were greatly affected by liquefaction. Liquefaction occurs when water-saturated sand becomes temporarily swamp-like during ground shaking. In the 1906 quake, the indirect cause of many of San Francisco's problems (lack of water resulting in an uncontrollable fire, amplified shaking) was liquefaction. --by Alex Hoff �

�