At 5:12 a.m. on April 18, 1906, an estimated magnitude 7.8 earthquake hit San Francisco, lasting for approximately 45 to 60 seconds. While the earth rolled and the ground split, the wooden and brick buildings of San Francisco toppled. Within half an hour of the San Francisco earthquake, 50 fires had erupted from broken gas pipes, downed power lines, and overturned stoves.

The 1906 San Francisco earthquake and subsequent fires killed an estimated 3,000 people and left over half of the city's population homeless. Around 500 city blocks with 28,000 buildings were destroyed during this devastating natural catastrophe.

The Earthquake Strikes San Francisco

At 5:12 a.m. on April 18, 1906, a foreshock hit San Francisco. However, it offered just a quick warning, for massive devastation was soon to follow.

Approximately 20 to 25 seconds after the foreshock, the large earthquake hit. With the epicenter near San Francisco, the entire city was rocked. Chimneys fell, walls caved in, and gas lines broke.

Asphalt that covered the streets buckled and piled up as the ground seemed to move in waves like an ocean. In many places, the ground literally split open. The widest crack was an incredible 28 feet wide.

The quake ruptured a total of 290 miles of the Earth's surface along the San Andreas Fault, from northwest of San Juan Bautista to the triple junction at Cape Mendocino. Though most of the damage was focused in San Francisco (in large part because of the fires), the quake was felt all the way from Oregon to Los Angeles.

Death and Survivors

The earthquake was so sudden and the devastation so severe that many people didn't have time to even get out of bed before they were killed by falling debris or collapsed buildings.

Others survived the quake but had to scramble out of the wreckage of their buildings, clothed only in pajamas. Others were naked or near naked.

Standing out in the glass-strewn streets in their bare feet, survivors looked around them and saw only devastation. Building after building had been toppled. A few buildings were still standing, but had entire walls fall off, making them look somewhat like doll houses.

In the hours that followed, survivors began helping neighbors, friends, family, and strangers who remained trapped. They attempted to retrieve personal possessions from the wreckage and scavenge some food and water to eat and drink.

Homeless, thousands upon thousands of survivors began wandering, hoping to find a safe place to eat and sleep.

Fires Start

Almost immediately after the earthquake, fires broke out across the city from broken gas lines and stoves that had fallen over during the shaking.

The fires spread ferociously across San Francisco. Unfortunately, most of the water mains had also broken during the quake and the fire chief was an early victim of falling debris. Without water and without leadership, it seemed nearly impossible to put out the raging fires.

The smaller fires eventually combined into larger ones.

South of Market Fire - Located south of Market Street, the fire was curbed on the east by fireboats that could pump salt water. However, without water in the fire hydrants, the fire quickly spread both north and west.

- Located south of Market Street, the fire was curbed on the east by fireboats that could pump salt water. However, without water in the fire hydrants, the fire quickly spread both north and west. North of Market Fire - Threatening an important commercial area and Chinatown, firefighters attempted to use dynamite to create firebreaks to stop the fire.

- Threatening an important commercial area and Chinatown, firefighters attempted to use dynamite to create firebreaks to stop the fire. Ham and Eggs Fire - Started when a survivor tried to make breakfast for her family not realizing that the chimney had been damaged. Sparks then ignited the kitchen, starting a new fire that soon threatened the Mission District and City Hall.

- Started when a survivor tried to make breakfast for her family not realizing that the chimney had been damaged. Sparks then ignited the kitchen, starting a new fire that soon threatened the Mission District and City Hall. Delmonico Fire - Another cooking fiasco, this time started by soldiers trying to cook dinner in the ruins of the Delmonico Restaurant. The fire quickly grew.

With the fires raging out of control, buildings that had survived the earthquake were soon engulfed in flame. Hotels, businesses, mansions, City Hall -- all were consumed.

Survivors had to keep moving, away from their broken homes, away from the fires. Many found refuge in city parks, but often those too had to be evacuated as the fires spread.

In just four days, the fires died out, leaving a trail of devastation behind.

Aftermath of the 1906 San Francisco Earthquake

The quake and subsequent fire left 225,000 people homeless, destroyed 28,000 buildings, and killed approximately 3,000 people.

Scientists are still trying to accurately calculate the magnitude of the quake. Since the scientific instruments used to measure the earthquake weren't as reliable as more modern ones, scientists have yet to agree on the size of the magnitude. Most, however, place it between 7.7 and 7.9 on the Richter scale (a few have said as high as 8.3).

Scientific study of the 1906 San Francisco earthquake led to the formation of the elastic-rebound theory, which helps explain why earthquakes occur. The 1906 San Francisco earthquake was also the first large, natural disaster whose damage was recorded by photography.