by Michelle Dong
Earthquakes are considered one of the most destructive natural disasters, but like many other catastrophic phenomenon in the world, scientists can’t predict when or where they occur. However, aftershocks from the initial earthquake can last for even years later. It’s important to learn about earthquakes since you’ll never know when you might be affected.
Earthquakes happen when two faults, or fractures of rock, suddenly slide against each other. The epicenter describes the location above the earth’s surface where the earthquake starts. Some major earthquakes have foreshocks, which are smaller earthquakes that come before the main one, but all mainshocks (largest and main earthquake) have aftershocks. In other words, one earthquake can trigger numerous more smaller earthquakes in the same place.
They are most common at fault zones, such as the Ring of Fire in the Pacific Ocean, where 80% of all earthquakes occur because of all the tectonic plates that surround the region. Tectonic plates can be described as puzzle pieces that make up the lithosphere, which is the solid, outer layer of the earth.
The reason why we feel the effects of earthquakes is because the friction that occurs when two faults push against each other is released as seismic waves. Scientists measure the seismic waves using seismogram recordings from seismographs, and depending on the size and length of the lines, the earthquake is classified by magnitude (the number usually associated with it). The Richter Scale, the most common way to classify the magnitude of earthquakes, depends on the energy that is released at the epicenter, and each level is 10 times stronger than the previous. Every earthquake ranked at 4.0 are noticeable by people indoors. The diagram below from U.S. Geological Survey gives a general idea about the severity of different magnitudes.
The Iran-Iraq earthquake that occurred on November 12th had a magnitude of 7.3 and was the deadliest of the year, killing 540 people. The second most destructive with a death toll of 370 was the Puebla earthquake in Mexico on September 19th . For more information visit this site.
If you ever end up in the unfortunate situation of experiencing an earthquake, or wanted to be prepared just in case, go here.