What causes temblors?

What causes temblors?

An earthquake is caused by a sudden slip in a subterranean fault, which is an existing weakness in the Earth’s crust caused by two plates moving against each other over a long period of time.

According to statistics, California has the most damaging earthquakes on average in the U.S. In any given year, some 37,300 quakes are recorded in California.

The world’s largest instrument-recorded earthquake in the world struck Chile on May 22, 1960. Studies show that it had a magnitude of 9.5. The 1906 earthquake in San Francisco that killed 3,000 people registered a 7.8.

The world’s most destructive single earthquake in the world tore apart Shansi, China on Jan. 23, 1556. Approximately 830,000 people died as a result of the quake.

Statistics show that about 1 million earthquakes, including those too small to be felt, occur each year across the globe.

In truth, seismic activity can never be predicted with 100 per- cent accuracy.

Some people believe man receives his best clues from animals, some of which are known to act differently just before an earthquake strikes. During the 1989 quake in Northern California, some Bay Area residents reported abnormal behavior from their pets just before the ground shook.

Experts believe an animal’s abnormal behavior in such circumstances is probably coincidental. And even if animals could feel a temblor before humans do, the U.S. Geological Survey contends that it would be impossible to determine beforehand what factor caused the animal’s change in behavior.

The first known instrument to record an earthquake dates back to 132 A.D., sources say. Chinese philosopher Chang Heng invented a large urn decorated with eight dragon heads facing the eight principal points of the compass. Below each dragon head was a toad with its mouth opened toward the dragon.

When an earthquake occurred, one or more of the eight dragon mouths would release a ball into the open mouth of the toad sitting below. The direction of the shaking determined which of the dragons released its ball.

Records indicate that the instrument detected an earthquake 400 miles away that wasn’t even felt at the location of the device.

The workings of Heng’s invention are unknown. Some scientists theorize that the motion of some kind of pendulum activated the dragons.

The best defense against an earthquake today?

Be prepared.

—Michael Picarella