On September 19, a massive 7.1 magnitude earthquake rocked Mexico. It knocked down dozens of buildings and killed more than 250 people. The death toll is expected to climb as more rubble is cleared. This quake happened on the anniversary of another earthquake that struck Mexico in 1985.
Earth's crust is broken into slabs of rock called tectonic plates. An earthquake happens when the edges of the plates push against each other. Mexico is one of countries in the world with the most earthquakes, says Julie Dutton. She's a geophysicist at the United States Geological Survey in Colorado. The reason for the large number of earthquakes is that the nation sits on top of three tectonic plates.
Just a week and a half earlier, an even larger earthquake struck in Mexico. It was 8.1 magnitude. Although that quake was stronger, it caused fewer deaths. That's because its epicenter, or central point, was in the ocean. The most recent quake's epicenter was 120 kilometers (75 miles) outside Mexico City. Mexico City is the country’s capital and home to
more than 11 million people.