1957 San Francisco earthquake facts for kids
| UTC time | 1957-03-22 19:44:22 |
|---|---|
| ISC event | 886234 |
| USGS-ANSS | ComCat |
| Local date | March 22, 1957 |
| Local time | 11:44:22 PST |
| Magnitude | 5.7 Mw |
| Depth | 15 km (9.3 mi) |
| Epicenter | 37°33′26″N 122°43′26″W / 37.5572°N 122.7239°W |
| Type | Oblique-slip |
| Areas affected | San Francisco Bay Area Northern California United States |
| Total damage | $1 million |
| Max. intensity | VII (Very strong) |
| Peak acceleration | 0.18 g |
| Landslides | Yes |
| Casualties | 1 dead, 40 injured |
The 1957 San Francisco earthquake was a moderate earthquake that shook the San Francisco Bay Area on March 22, 1957. It happened at 11:44 AM local time. This earthquake is also known as the Daly City earthquake of 1957 because it caused the most damage there.
The earthquake had a magnitude of 5.7. Its strongest shaking was rated as VII (Very strong) on the Mercalli intensity scale. The earthquake's center was just off the San Francisco Peninsula, close to the famous San Andreas Fault. People felt the shaking across parts of Northern California and Central California.
Before and after the main earthquake, there were smaller tremors called foreshocks and aftershocks. These lasted for several months but did not cause much damage. The total damage from the earthquake was about US$1 million. Only one person died, and about 40 people were injured.
Contents
Understanding Earthquakes: Tectonic Plates
The Earth's surface is made of huge pieces called tectonic plates. These plates are always moving, but very slowly. The San Andreas Fault System (SAFS) is a group of faults in California. It helps to handle the movement between two big plates: the Pacific Plate and the North American Plate.
The SAFS stretches from the Mendocino Triple Junction in the north to the Salton Sea in the south. Most of the movement along these faults is a "right-lateral strike-slip." This means the land on one side moves horizontally to the right compared to the other side. Other types of faults, like those where land moves up or down, are also part of this system.
The 1957 Earthquake Details
Before the main earthquake, there were eight smaller earthquakes, or foreshocks. The biggest foreshock had a magnitude of 3.8. Scientists studied how the ground moved during the main earthquake. They found that it was different from the much larger 1906 San Francisco earthquake.
The 1957 earthquake involved a type of movement called "oblique-slip." This means the fault moved both horizontally and vertically. The eastern side of the fault moved up compared to the western side. The horizontal movement was much smaller than the vertical movement.
Earthquake Damage and Effects
The damage from the 1957 earthquake was not very severe. It mostly affected things inside buildings, like furniture, and caused cracks in plaster walls. The total cost of damage was estimated at $1 million. This amount did not include the value of damaged items inside buildings.
The worst effects were seen in the western part of Daly City, California and near the Lake Merced area in San Francisco. The main reasons for the low amount of damage were that the shaking did not last very long and it was not extremely intense.
Measuring the Shaking
The 1957 earthquake was felt over a large area, about 12,000 square miles. It was very important for scientists because 13 special instruments recorded the strong ground motion. These instruments showed how much the ground accelerated during the earthquake.
The highest ground acceleration recorded was 0.13 g in Golden Gate Park. Another reading of 0.18 g was taken on the fourteenth floor of a building in San Francisco. These measurements helped scientists understand how earthquakes affect buildings and the ground.
