What is an Earthquake?

An earthquake is what occurs when two blocks of earth suddenly slip past each other. The surface where the slip occurs is called the fault or the fault plane. The location between the earth's surface and where the earthquake starts is called the hypocenter. The location directly above that on the surface is called the epicenter.

Sometimes earthquakes have smaller quakes that follow, these are called foreshocks. Scientists can't tell if these are foreshocks until the larger earthquake happens. These are known as the mainshock. These shocks always have after shocks that follow. Depending on the size of these mainshock's, aftershocks can continue for weeks, months, or even years.

What Causes Earthquakes and Where do They Occur?

The earth has four crucial layers, this includes: the inner core, outer core, mantle, and crust. The crust and top mantle make up a thin skin on the surface of earth. This skin is made up of several pieces covering the surface of the earth. These pieces are constantly, but slowly, moving around, sliding past and bumping into each other. These are known as tectonic plates. The edges of tectonic plates are known as plate boundaries.

Plate boundaries are made up of many faults, these are where the majority of earthquakes occur. The edges of the plates are rough, this means that get stuck when the other plates continue moving. When these plates move far enough, the edges unstick on one of these faults. These are known as earthquakes.

How are Earthquakes Measured?

Earthquakes are recorded by instruments called seismographs. The recordings seismographs create are known as seismograms. The seismograph has a base that sets firmly in the ground, and a handing weight that hands free. When earthquakes occur, the base moves, but the hanging weight doesn't. The difference between position in the shaking part of the seismograph and the motionless part is what's recorded.

How do Scientists Locate Where Earthquakes Occur?

The size of the earthquake depends on two factors: size of the fault and the amount of slip on the fault. This is something that can't be measured simply with common measuring tool. The scientists use seismogram recordings made on the seismographs at the surface of the earth to determine how large the earthquake was. A short wiggly line that doesn't wiggle much means that it's a small earthquake. A long wiggly line that wiggles a lot indicates a large earthquake. The length of this wiggle depends on the size of the fault and the size of the wiggle depends on the amount of slip.

This size of a earthquake is called the magnitude. This means that there's only one magnitude per earthquake.

Safety Procedures for Earthquakes

How can I prepare?

To prepare for an earthquake, it's a good idea to become aware of your surrounds and evacuation plans. To do this, you should pick a safe place in each room of your frequently visited locations. A safe place would be under a piece of furniture or against an interior wall away from windows, and tall furniture that could fall on you. Practice drop, cover, and hold. It's also a good idea to keep equipment useful for emergencies, like a flashlight and safe clothing. Make sure your home is up to earthquake standards. This may include being anchored to foundations, bolting and bracing water heaters and tall furniture, ect. Also make sure to install strong latches and bolts to furniture, this will ensure the utmost safety.

What should I do during an earthquake?

If you're currently inside when shaking occurs, drop, cover, and hold on. Make sure you move as little as possible. If you're on a bed, stay there, curl up, and hold on. Protect yourself with surrounds, like pillows and blankets. Make sure to stay away from windows or anything else that can cut you.

If you're outside when shaking occurs, find a clear spot and drop to the ground. Stay there until the shaking stops, make sure you're away from buildings, power lines, trees, street lights, ect. If you're in a vehicle, pull over to a close clear location and stop. Avoid bridges, overpasses, and power lines to the best of your ability. If something dangerous falls on your vehicle, like a powerline, don't get out, wait for assistance.

What do I do after an earthquake?

After an earthquake, be aware that disaster may continue. This means that you need to prepare for potential after shocks, landslides, or even tsunamis. Each time you feel an aftershock, drop, cover, and hold on. These shocks can occur for long periods of times. Before you do anything, check yourself for injuries and get treatment if necessary. This includes if you're going to help an injured or trapped person. Check for damage around your house and make sure everyone is out of the house if it's deemed unsafe. Listen to portable battery-operated or hand-cranked radio for emergency information and instructions. Immediately clean up anything spilled that's deemed dangerous. Lastly, make sure you're aware of your surrounds-outside and inside too.

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By: Marissa Spencer