Science 6 Sylvie K and Abigail T

Ms.Kee Pd. 8 Earthquake Paragraphs

Earthquakes are destructive natural disasters that can be felt by people many miles away from the epi-center of the quake. Every day there are earthquakes, just not all of them are destructive. Some are so small, that they aren’t noticed by anyone except scientists.

An earthquake is a violent movement of Earth’s surface. It can be a sudden jolt releasing stress from faults. A group of seismic waves can cause a tremor. A temblor can also be sudden movement of tectonic plates. Tectonic plates are huge rock slabs under the Earth’s surface. There are seven major plates but many smaller ones. These plates are always moving. After earthquakes there are aftershocks, which are tremors after the main quake. Aftershocks can cause more damage than earthquakes because they can last longer than the first tremor.

Tremors can occur in many places. One way an earthquake can arise is when part of the earth, (plates), move quickly. A quake can also occur when two or more plates rub against each other. A fault is a crack, or fissure. Eighty percent of major tremors happen in the Ring of Fire due to its weakness. The Ring of Fire is a subduction zone. Plate boundaries are where plates meet. A divergent boundary is when two plates diverge. Transform boundaries slide against each other. A subduction boundary is when one plate slips under another. When two or more plates move toward each other, it is called a convergent boundary.

Earthquakes can be underwater or on land. When there is a quake underwater, it may cause a tsunami. Where a plate is weak, a tremor is likely to occur. The edges around the Pacific Ocean are vulnerable to an earthquake because they are weak (Ring of Fire). The Philippine plate and the North American plates meet in Japan which causes many quakes. The San Andreas fault, located in California has many earthquakes because the Pacific and North American plates meet there. It is found that there are about one million earthquakes around the world each year.

Earthquakes release primary and secondary waves. Waves spread out from the epi-center of the quake. Secondary waves move the land from side to side. Primary waves stretch and compress as they travel through the Earth. Seismic waves spread out from the focus of the quake. The basic seismic waves are body and surface waves. Body waves move through the inner part of the Earth. Surface waves travel over the surface of the Earth. Land waves are formed when primary and secondary waves combine. Waves shake the Earth in many different ways.

In history, there have been some horrible tremors. Ninety-five people were injured in 1960 in Chile. The tremor stretched to Japan and Hawaii and even injured people there! A large tsunami swept Japan after a quake. It caused a lot of destruction. There were fifty-thousand fatalities that were a result of a temblor in Bam, Iran, 2003. In 193( there was a terrible earthquake in Chile at the bottom of the sea. Surface waves in Mexico City, 1985 caused an earthquake. Also in Mexico City, 1985, there was a terrible quake that measured 8.1 on the Richter Scale. After the tremor in Peru, 1983, there was a large landslide which was extremely dangerous. The San Francisco earthquake in 1906 was caused by crashing plates. A large tremor in Landers, California in 1992 was triggered by shifting fault lines.

Earthquakes cause a lot of damage. Often, they destroy buildings. After a quake, you may not have electricity. Many tremors cause fires. It is hard to put these fires out because pipes may have broken which lets water out. Then there is not enough to put out the fire and the drinking water is dirty and people may get diseases. Streets and highways may get ruined and cars get totaled due to quakes. Underground explosions can be caused by quakes as well. Sadly, there are many fatalities as a result of earthquakes.

Scientists measure earthquakes on scales to figure out how strong they are and to measure movement. The Mercalli Scale measures magnitude (seismic waves). It goes from I to XII. The Richter Scale is used to measure the strength of a quake. It is named after C.F. Richter. Seismographs and seismometers are also used to measure magnitude. There are seismograph stations all over the world. A seismogram shows how the ground moves. Laser beams are used to detect ground movement. To measure water movement a tiltmeter is used.

You have to know how to stay safe during an earthquake. Always keep canned food handy in case you have to evacuate. Make sure to keep a can opener close to your canned food so you remember it. Keep bottled water to drink. Do not keep glass bottles because they can break. If you are inside during an earthquake, stay inside and go under a strong bed. You will also be safe during a temblor if you stay under a strong table. Doorways are sturdy, so if you are inside, you should stand under one. Windows may shatter during a quake, so stay away from them. If you know about an earthquake in advance, you should tape up your windows using packing tape or nail board onto the window frame. One good way to stay safe during a temblor if you are outside is to stay away from buildings and trees. Also stay away from power lines. Go to an open area and you will be ok.

Scientists know a lot about earthquakes, but they still have some to learn. What scientists don’t know is how to accurately predict earthquakes. They are studying seismic activity and will hopefully learn many things about these harmful quakes.

Bibliography

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