The Sephardic Heritage Museum Explores THE LIFE AND ESCAPE of the JEWS OF SYRIA

Past Articles:
HAVE YOU EVER WONDERED… WHAT ARE EARTHQUAKES AND WHAT CAUSES THEM TO TAKE PLACE?





Earthquakes are a shaking or trembling of the ground. Some earthquakes are slight tremors that are not even noticeable. Others are so powerful that they can tear down buildings, mountains, and entire cities in less than a minute! In 1995 there was an earthquake that lasted barely twenty seconds in Kobe, Japan – yet it was so violent that it killed 6,400 people and caused
$200 billion in damages.

In most earthquakes, a few minor tremors, or vibrations, are followed by an intense burst that lasts for one or two minutes. A second series of minor tremors, called an aftershock, may occur over the next few hours. An aftershock is a smaller earthquake that occurs after a large earthquake, in the same area as the main shock.

Why the Earth Shakes and Quakes

Earthquakes occur when the moving tectonic plates that make up the surface of the Earth slide past or crash into each other.

The starting point of an earthquake below the ground is called the hypocenter, or the focus. This is the section in the crust where two tectonic plates collide. The epicenter of an earthquake is the point on the surface that is directly above the hypocenter. Earthquakes are strongest at the epicenter and become gradually weaker farther away.

Primary waves (p-waves) are the first waves of an earthquake; they travel through the earth's crust, mantle, and core. Next come secondary waves (s-waves), which are slower and only travel through the crust and solid mantle. Surface waves (also called l-waves) travel along the top of Earth’s crust and are the strongest waves, with a motion similar to ocean waves. As the movement of l-waves takes place on the surface of Earth itself, these waves cause the most damage.

Measuring Earthquakes

In 1935 Charles Richter developed a system to measure the magnitude (amount of energy released in something) of an earthquake. This system measures earthquakes by using what’s known as the Richter scale. Each whole number on the Richter scale indicates a tenfold increase in amplitude (greatness in size). So, a 7.5 earthquake on the Richter scale actually has ten times the amplitude of a 6.5 earthquake. There is no upper limit on the Richter scale, meaning that it could be used to measure earthquakes of a ten or more magnitude if one ever occurred. As of now, though, the most devastating earthquakes we know of are 8 or 9 on the Richter scale.

If an earthquake is rated 1, you can hardly feel it. In a level 2 earthquake, people who are resting may feel it, especially if they're near the top of a tall building. A level 5 earthquake can cause dishes and windows to break, and a level 6 earthquake can cause heavy furniture to move around. A level 8 earthquake is enough to cause many buildings to fall down.Did You Know?

The most powerful recorded earthquake in the world occurred in Chile on May 22, 1960. The earthquake measured 9.5 on the Richter scale, and created seismic waves (waves of energy that travel through Earth’s layers) that went all around the planet and shook the entire Earth for many days!

Tsunami

(pronounced: tsoo-nah-me)

Earthquakes also occur in the ocean. Usually these earthquakes just shake the water and are not noticeable. But when the ocean floor is violently shaken – usually by an earthquake, landslide, or a volcanic eruption – it can cause a tsunami.

A tsunami is a series of huge, powerful, and destructive waves. Tsunamis can travel at speeds of up to 500 mph, with waves over 100 feet high! The waves in a tsunami usually strike in a series of a dozen or more, at intervals ranging from five minutes to one hour apart. The largest tsunami wave ever recorded was a 279-foot-high wave, which struck Japan in 1771.