In 1906 San Francisco had a devastating earthquake - registering around 7.7 to 8.3 on the Richter scale. The disaster began with an earthquake in the early morning of Wednesday, April 18, and when the fires were extinguished three days later, at least two hundred thousand San Francisco residents were homeless.
Chicago resident George Lawrence had devised ways to take aerial photographs. As soon as news of the disaster had reached Chicago, he made plans to go to San Francisco with his Captive Airship and crew. With the Captive Airship he knew he could take aerial photographs of the prostrate city that no one else in the world could take. He was gambling by going to the devastated city, but he took the chance knowing there would be an international market for his photographs if he succeeded. Lawrence was, first and foremost, a commercial photographer.
Lawrence's photographs were a commercial success. More important for today, many of his photographs have been preserved and today are a primary source of information for historians and genealogists. If your ancestors lived in San Francisco, George Lawrence's photographs can show you the devastation they endured.
You can see several of George Lawrence's photographs at http://www.rtpnet.org/robroy/lawrence/landscape.html.
You can read more about George Lawrence and his aerial photography techniques at http://www.rtpnet.org/robroy/lawrence/intro.html#articles. The US Geological Survey has some background information on San Francisco's 1906 earthquake and even more photographs at: http://quake.wr.usgs.gov/info/1906/index.html. Still more photgraphs can be found at http://www.sfmuseum.org/1906/photos.html.
Finally, the Virtual Museum of the City of San Francisco is building a register of everyone who was in San Francisco at the time, both survivors and those who perished, at http://www.sfmuseum.org/1906_eq_quests/eq.htm.