The 1906 San Francisco earthquake: a centennial contemplation.

The publication of this issue of PrehospitalandDisasterMedicine coincides with the centennial of the 1906 Great San Francisco Earthquake. The 1906 San Francisco Earthquake does not rank with the larger earthquakes in world history and is not even the largest earthquake in US history. In fact, readers of this journal will recall many recent earthquakes that produced exponentially greater health damage in Kobe, Japan (1995), Chi-Chi, Taiwan (1999), Marmara, Turkey (1999), Gujarat, India (2001), Bam, Iran (2003), South Asia (2004), and Kashmir, Pakistan (2005). Nevertheless, the 1906 San Francisco Earthquake was one of the most notorious disasters of its time. In that age of telephone and telegraph, news of the Great Earthquake in the city widely celebrated as the "Paris of the West", rapidly spread around the globe. The secondary Great Fire remains the worst urban fire disaster in United States history and was unequalled in the world until the bombing raids of World War II. Until Hurricane Katrina last year, the 1906 San Francisco Earthquake was the largest disaster caused by natural events in US history. Finally, the 1906 San Francisco Earthquake offers several lessons learned in disaster medicine and emergency management that are worth re-visiting today. • An understanding of this disaster is facilitated by the conceptual framework developed by the Task Force in Quality Control in Disaster Medicine. The hazard underlying the 1906 San Francisco Earthquake was the northernmost segment of the San Andreas fault, spanning 296 miles from San Juan Bautista to Cape Mendocino, California. The primary event was the rupture of the fault line (earthquake) that occurred at 05:12 hours (h) on 18 April 1906. The epicenter most likely was in the Pacific Ocean, two miles west of San Francisco's Golden Gate Park. The magnitude of the quake has been estimated at 7.7-7.9 Richter. Much of the city of San Francisco then and now was constructed on three unstable surfaces: steep hillsides, rolling sand dunes, and land-filled marshes. The secondary event was the Great Fire that began at 52 locations across the city within 30 minutes after the quake and continued to rage for three days. Many fires were caused by ruptured gas lines, particularly in collapsed structures in lowlying areas built on land-fill. The population-at-risk included the 410,000 people who lived in San Francisco, as well as those in communities up and down the fault segment from Shelter Cove to San Juan Bautista.' Because the earthquake occurred early in the morning, most of the population at risk was sleeping indoors when the quake struck. The primary earthquake and an initial aftershock damaged buildings throughout San Francisco, especially in the low-lying areas built on former marshes. The City Hall, the Grand Opera House, and several firehouses, churches, and hotels were promptly demolished.'' Buildings tending to collapse included poorly built, wooden structures, those with poorly built brick chimneys, and those constructed with unreinforced masonry. The quake also knocked out the city's underground water mains and the critical pipeline between the city and its nearby reservoirs, local telephones, the telegraph cable that connected San Francisco with the rest of the US, and the public transportation system (cable cars and street cars). In addition, the quake demolished many structures in communities outside of San Francisco, including most of the buildings in Santa Rosa, the main building at Agnews State Hospital for the Insane in Santa Clara County, and many buildings on the campus of Stanford University.