Earthquakes are among the most destructive forces on Earth because they can cause the most damage in the least amount of time. Even more than your brother.
FEELING SHAKY?
Don’t get up now, but there’s a 100% chance that an earthquake is going to register somewhere in the world while you’re reading this page. That’s because there are about a million earthquakes per year—about one every 30 seconds. You probably won’t even feel it, though: humans feel only about 60,000 earthquakes a year—about one every 10 minutes somewhere on the planet. And most of these don’t do any damage at all.
The average earthquake lasts less than a second, but the most damaging ones, called great earthquakes, can last for as long as several minutes. Fortunately, there’s only about one of these a year.
TIDAL WAVE!
Earthquakes can also cause huge high-speed waves known as tsunamis (soo-NAM-mee), or tidal waves. (Volcanic eruptions can also cause these.)
When an earthquake occurs somewhere beneath the ocean, the ocean floor shifts, creating a huge ripple in the water. This ripple spreads out in a circle, at speeds up to 600 miles per hour. Because the ocean is so deep, the ripple is barely noticeable…at first. But as the ripple nears the shallows and the shore, a wall of water is pushed upward, creating a devastating tsunami.
Because they appear with hardly any warning, tsunamis have wreaked havoc on coastal communities for centuries. Today they can be detected by satellites, which gives local authorities time to evacuate people in danger. But just in case you’re alone on a secluded beach, here’s nature’s warning sign: If the ocean’s water level drops drastically in a very short period of time, get to high ground as fast as you can. A tsunami is coming!
THE BIG ONE OF ’64
Many people think the earthquake capital of the U.S. is California, but it’s actually Alaska. More quakes occur there per year than in the rest of the country combined.
America’s strongest and largest recorded earthquake rocked the southwest coast of Alaska on March 27, 1964. Earthquake waves swept through the land at more than 7,000 miles per hour. Buildings, bridges, and roads crumbled. Railroad tracks bobbed up and down, hurling trains into the air. In some areas, the earth dropped 35 feet, in others it rose 50 feet. Even thousands of miles away, the ground was affected—NASA noted that it lifted 2 to 4 inches in Florida and in Texas.
Tsunamis caused by the great Alaskan quake swamped at least 68 fishing boats, and crashed into the shores of Canada and Hawaii. Amazingly, in all this devastation, only about 115 people died. The reason? Few people lived in Alaska in 1964.
There are more than 600 active volcanoes on Earth. At least 80 of them are in the ocean.