The 1994 Bolivia earthquake occurred on June 9, 1994. The epicenter was located in a sparsely populated region in the Amazon jungle, about 200 miles from La Paz.^[1]

Harvard assigned it a focal depth of 647 km and a magnitude MW of 8.2, making it the largest earthquake since the Sumbawa earthquake of 1977.^[1] It is also the largest earthquake ever recorded with a focal depth greater than 300 km.^[2] South America also experienced the second and third largest earthquakes at focal depths greater than 300 km: Colombia, 1970; and northern Peru, 1922.^[1]

Description

The rupture was located on the Nazca plate where it is being pushed beneath the mantle of the South American continent.^[2] It shook the ground from Argentina to Canada and its oscillations were the first to be captured on a modern seismic network.^[2] Light damage to buildings was felt in Sao Paulo, Brazil, and Toronto, Canada.^[3]

The quake also destroyed scientists' opinions on deep earthquakes. According to the squeeze theory of earthquakes, pressures and temperatures at the depth of 200 to 400 miles should be so great that rock should not undergo frictional sliding; most geologists believed that the crushing pressures and increasing heat below a certain depth compressed rocks into forms that were denser, creating huge cracks in the Earth's surface.^[3] The Bolivian earthquake was 395 miles below sea level and, according to geologist Paul G. Silver, "[the earthquake] looks and acts and talks like these shallow earthquakes. But it shouldn't exist."^[3]

References

fa: ( ) ka: (1994)