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Another way we can keep ourselves safe from earthquakes is by making the buildings safer. When an earthquake occurs, many buildings could topple over or break apart. If we give the buildings more support, then it will be a better chance that the building will stay intact. This way we can save man lives.
When scientists try to locate the epicenter, they use three seismographs. This method is called triangulation. The method of triangulation is based on the speed of the three seismic waves. Scientist have to use these steps to actually locate the epicenter. First, you have to find the arrival distance. Next, you find the distance from the epicenter. Then finally you plot the distance on the map. After that you use a compass to draw the circle. This will tell you about the radius of the circle.
The energy supported by the motion is the convection from the inside of the Earth. Heat acts like electricity that would be uses in a light bulb.
Chapter 6 lesson
An Earthquake is a rupture or sudden movement of the rocks along a fault. When a fault slips or breaks , it causes an earthquake to occur.
When our earth's lithosphere plates bent, it can move and act like a rubber band. After rubber bands are stretched, the energy stored to change shape without cracking is, called elastic strain.
Faults and Earthquakes
Both faults and earthquakes are related. Their similarity include the two faults sliding horizontal toward each other. Faults are cause of earthquakes and other natural things.
Where the earthquake starts. The focus is where the earthquake starts, where everything happens that is earthquake related.
Plate boundary on maps are shown as a line but in real life the plate boundary are more like zones and that is where the words fault and zone came to earth.
Plate Boundaries and Earthquakes
Different types of plate interact at different plate boundary across earth. Earthquakes size and depth depend on what type of plate boundary it is on.
Divergent Plate Boundaries
At Divergent plate boundary rock break under tension stress. Many of these boundary's occur at shallow parts of earths crust.
Convergent Plate boundary
At these boundary rocks break under compression stress forming reverse faults. Convergent plate boundary make the deepest earthquakes and the most devastating.
Transform Plate Boundary
At this boundary rocks slide pass each other (horizontally) forming a fault we call a strike-slip fault. This boundary creates rather shallow earthquakes but can be destructive.
Earthquakes Away from Plate Boundary
Some earthquakes can form in the middle of nowhere but can be deadly. people think that earthquakes can only form at plate boundary, but they are wrong. One earthquake changed the course of the Mississippi, and was nowhere near a plate boundary.
Cause of Earthquakes
Earthquakes occur when elastic strain energy builds up at the point of the rock. Also other stress and tensions put more pressure on the rock and soon it move and carries waves through Earths surface.
Earthquakes and Seismic Waves
When you throw a rock in a pond waves travel outward from the spot the rock hit. This is like seismic waves
What are seismic waves
Seismic waves are waves of energy, that can be very destructive depended on the type of seismic wave. All of the seismic waves are produced at the center at the center of an earthquake.
What are seismic waves?
Seismic waves are the type of waves that shift up and down, and side to side. During an earthquake seismic waves are released from the focus.
Surface waves are a totally different seismic wave when compared both to the S-wave and the P-wave. This surface wave is created when Both the P-wave and the S-wave reach the surface, and the energy gets trapped there. The surface wave is the slowest wave, but it also causes the most destructive earthquake because of its slow, swaying, rolling motion.
Surface waves is the second most major seismic wave. This wave is slower then the P- wave, but can still cause a destructive earthquake. The S-wave causes rock particle movement to move in a wavy motion, causing perpendicular wave travel. Also the wave movement is caused by the shear waves.
How do seismic waves travel?
Seismic waves travel through earths crust. This energy can refer to when you pull back a rubber band and let it go. It starts at the epicenter (the point on earths surface directly above a focus point) and travels at the shallows of earths surface.
What are the different types of seismic waves?
There are three major types of Seismic waves. There's the P-wave, S-wave, and the Surface waves. All three seismic waves cause massive damage to all the world, including our homes. Seismic waves are a big part that supports the process of an earthquake.
One of the major seismic waves is the Primary waves (P-wave). Out of all the seismic waves, this wave is the fastest. Their is measured to be between 5km to 7km. The P- wave causes rock particles to move like the wave, it compressed waves.
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Speeds of Seismic Waves
Earthquake waves are like people running in a race. They first star together and toward the end they end up separated.
Paths of Seismic Waves
S-waves travel through earths mantle and maybe toward the lower part of earths crust. Surface waves travel in earths surface or on top of earths crust.
Mapping Earths Internal Structure
Scientist map seismic wave throughout earth and even see where they can hit or travel to. In the twentieth century scientist found out that some waves don't hit larger areas of earth.
Seismic waves are released when a earthquake ruptures or when rocks along a fault slip. There are many different types of waves, but one thing they have in common is that they can be destructive.
Using Seismic Wave data
There are many different types of seismic waves and they travel at different speeds. some travel deep in earths crust and other times it travels literary on earths crust.
Earthquakes can be measured by a device called a seismograph. This device shows us how strong a earthquake is when it happens.
How are Earthquakes Measured
Seismographs are devices that sit on bedrock and when ever the ground shakes the pen hovering over the paper moves and however high the lines are the stronger the earthquake is. When you go on the news and they show you a bunch of lines, that means to was make by a seismograph.
Recording Seismic Waves
Seismic waves travel through earth and shake the ground with it. Seismographs record the information and then is brought up to scientist to investigate on.
Mechanical seismographs are like regular seismographs but are more sturdier and and more advanced then the first one. The new ones are more accurate and also look better.
Reading a Seismogram
A seismogram is a piece of paper recording ground movement and showing how bad it was. It may look like a bunch of lines but it shows how large the earthquake was.
Locating the Epicenter
Chapter 6 lesson 3
Measuring Earthquake Size
Earthquakes come in many different sizes and shapes and that means there are many different ways to measure them.
The Magnitude scale is used to measure the energy of the earthquake. It was based on amplitude, height, of ground motion. This scale range from about 0 to 9. The increase of one number is 10 times more in the ground shaking.
Richer Magnitude Scale
This scale was the first one to be approved an then used for rating magnitudes of earthquakes, or there size.
Moment Magnitude scale
Scientist these days use more accurate scales and so they aren't off on there grading. This scale is based on the amount of energy released by a earthquake.
Earthquakes and Intensity
Earthquakes can be described as the amount of damage they do. Scientist go to people and listen to what they say and go to buildings and see how much of it was wreaked.
Effects of Shaking
When earthquakes shake the ground they cause thing to collapse and cause serious damage to city's and homes.
Plotting Intensity Values
This type of map like thing is used to show areas where earthquakes appear most often and how powerful they are.
Features of an earthquake
The reason scientists measure seismic waves is because the want to know where an earthquake will occur and how big will it be. The scales that we use measure distance of the seismic waves from the earthquake.
Chapter 6 Lesson 4
Earthquakes Hazards and Safety
Earthquakes can cause more than just the ground shaking it can also cause fires,liquid fraction, landslides and even tsunamis.
One of the most common hazard of an earthquake is a fire. When an earthquakes occur, the rupture destroys electrical pipe lines, broken pipelines, and gas pipes.
In areas where there's steep slopes, earthquakes can make the soil go lose and then everything falls. The dirt goes from packed to loose and messy.
This is when dirt and soil acts like a liquid. That is bad because you wouldn't want your house or the building your in sink into the ground and collapse.
Some earthquakes start in the ocean and when they do the can cause a tsunami to form. A tsunami is when something in the ocean shifts and causes a disturbance in the water and cause it to make huge waves.
Avoiding Earthquake Hazards
To avoid earthquakes don't live too close to a fault or plate boundary. There are many hazards in California because a fault runs through it and is active a lot.
Avoiding earthquake Hazards
Determining Earthquake Hazards
Scientist go to active faults, so they can see where the past earthquakes occurred. Also they have a map showing where the loose sediment is and the nearest local rocks. They use this information to predict where the next earthquake will be.
California has a big earthquake hazard and it is good if you are building something follow earthquake safety rules. First don't build houses on dirt or mud because it can become liquid fraction or a landslide can occur.
Earthquakes and structures
Types of Structures
If your building survives massive earthquake that means the strength and quality of your building is good. Some building were built cheap and collapsed when a earthquake came which could have cost lives.
Earthquake Resistant Structures
To keep people safe, they use the safest material to keep the building together. To do is they have to have tests, seeing if the structures are safe enough. We have seen that steel plates and rubber are the best materials to use.
If a earthquake happens in your home go under something like the dining table or just something that can protect your head and body. If you are outside say in a area away from trees and power lines.
Before an Earthquake
Before a earthquake strikes you and your family you should have a drill on what to do when it happens. Drills like you do at school you should also do at home. Practice with your family about four times a year.
During an Earthquake
If you are indoors, stay insidde. Move away from the windows and also any objects that could fall on you from high places. Stay under and sturdy roof. Most of all do not touch any electrical items or power lines.
After a Earthquake
You should stay calm and remember what you did in your family drill for earthquake disaster plan. If you smell gas or any flammable substance leave the building or area immediately and then find a adult or your parents.
Surviving a Earthquake