by Sam Schultz and Mitchell Nabata
Earthquakes Home Page
Introduction for Earthquakes:
An earthquake is a shaking of the earth’s surface, known as the crust. The earth’s crust is made of huge rock plates, which can shift to cause an earthquake.
There are millions of earthquakes everyday! Most earthquakes are not big, so no one notices them. The ground beneath you may seem solid, but an earthquake can change your life completely in only a matter of minutes.
How Earthquakes are Formed:
Earthquakes can happen anywhere: land, mountains and oceans. Depending on where earthquakes happen, there are different outcomes. For example, if you have a big earthquake in the middle of a body of water, then there could be a tsunami following the quake.
Most earthquakes happen when two rock plates meet, creating friction. The force is so strong it will send shockwaves through the ground, creating an earthquake. The earth’s tectonic plates can be very elastic and but can snap when placed under too much pressure.
Faults are places on the earth’s crust that are weak spots of rock. Most earthquakes come from huge lines of these faults all across the world. These are called fault lines.
A man named Alfred Wegener came up with the idea of continental drifting. He thought that all the continents were one big island, and that they split apart because of the earth’s plates shifting, like it does in earthquakes. Scientists have discovered that parts of his theory are true. Using a map of the earth’s fault lines, you can actually piece together the continents forming this big island. The fault lines show exactly where the one continent spilt. When it split it created these massive fault lines. It is believed that the tectonic plate’s theory is still happening. This large super continent is called Pangaea.
A seismograph is a measurement machine that measures earthquakes. It’s used by seismologists in order to detect earthquakes. A seismograph records vibrations in the earth’s surface and will pick up even the slightest vibration. This is recorded on a sheet of paper under the seismograph needle that writes it. When there are vibration, the needle sways, causing bigger lines to be drawn. See diagram S1.
But there was another kind of seismograph, made much earlier by the Chinese. When there is large vibrations in the earth, this seismograph will drop a small metal ball from the mouth of a metal dragon and into the mouth of a metal toad. If one of these metal balls landed in a toad’s mouth, there will most likely be an earthquake in the direction of the toad that it landed in. See diagram S2
Diagram S1 is a modern seismograph (one the left) and Diagram S2 is the Chinese seismograph (on the right)
The Richter Scale:
In 1930, a scientist named Charles Richter invented the Richter scale (pronounced Ricter). This scale is used to measure the amount of energy is produced by an earthquake; this generally means how devastating it will be. When an earthquake happens, this devise will measure the earthquake’s energy, and it will measure anywhere from 1-10 on the scale. When the Richter scale was first invented, it was named the “magnitude scale”; it was later changed to the Richter scale after Charles Richter.
On this scale, each number is 10 times larger than the previous number, meaning there is a huge difference between 2 and 4. A 2 on the Richter scale is hardly noticeably, while a 7 is powerful enough to destroy an entire city.
There are other scales for measuring earthquakes, such as the European Macroseismic Scale (EMS), or the Shindo scale from Japan. Even though they are different, they have the same purpose, to measure earthquakes.
Chart from ScienceFocus™7 textbook
Safety from Earthquakes:
Research indicates there are at least 9 main safety concerns for earthquakes.
1. Make sure furniture is secure, so it does not hurt anyone.
2. If you live in an area exposed to earthquakes, make sure your home has adequate safety precautions.
3. You should have a plan of what to do if an earthquake starts.
4. Have multiple fire extinguishers in your home.
5. Are you or any neighbours ready to assist one another?
6. Do you know how to turn off the gas supply?
7. Keep under a stable object.
8. Don’t be near windows.
9. Make sure you’re not in danger of anything falling on you.
Hopefully, these things will help people survive earthquakes.
Facts about Earthquakes:
Every year there are thousands of earthquakes, though most you can’t even feel. Small earthquakes just shake the ground a little, but the larger earthquakes can even create large cracks in the earth.
The place where all earthquakes are created, no matter how it was created, is the earthquake’s focus point. It is the focus, centre point of an earthquake, where the plates shift. The epicentre is a spot vertically above the focus of an earthquake. About 75% of earthquakes in the world happen in a region of the Pacific Ocean on the fault lines, called the Ring of Fire. Earthquake cracks can be anywhere from a couple centimetres to hundreds of kilometres.
The darkened part is a picture of the Ring of Fire.
When plates shift, it creates shockwaves that go though the earth, the shock waves are the actual earthquakes, and they go through the earth vibrating it as they go, causing all the destruction. These shockwaves can travel at speeds of 16 km per second. As shockwaves move away from the focus, they lose energy and slow down. All these shockwaves could also be called tremors.
The scientists that study earthquakes are called seismologists. Seismologists study how an earthquake works, how to measure it, and when one might come. Some seismologists use laser stations set up randomly in areas of earthquake activity, these laser stations can detect even the slightest vibration in the earth around that area. These laser stations are great tools to know when an earthquake might occur. With the information these scientists gather, seismologists and structural engineers try to make buildings stronger so they have a better chance of withstanding an earthquake. Now some buildings are even being designed with rubber and special steel pads in hopes to absorb or slow down the shockwaves of the earthquake.
There are three classifications of shockwaves. The first is surface waves. These are shockwaves that move through the earth’s crust. Second is primary waves, which are shockwaves that pass through liquids. And finally secondary waves, the shockwaves that can not pass though liquid, so they can not move through the earth’s molten core. Vibrations in the ground, which are caused by an earthquake far away from where you are, are called teleseisums.
There are millions of earthquakes every year (most very small) and most big ones last about 1 minute. Sometimes, we humans can also create earthquakes from our machinery, this is called induced seismicity. Sometimes, scientists measure the stress on the earth’s plates, this could also help them predict when an earthquake might happen. Too much stress and they know something will probably happen. These plates are also called, tectonic plates. Its not always an earthquake that’s formed Sometimes when these plates shift, there is a chance that they will crack open and slowly form a volcano,.
This disaster causes much destruction. It is said to be one of the most devastating disasters. When an earthquake strikes, it causes damage across a huge area of land. When a really large earthquake strikes a city, it will be almost completely destroyed after the earthquake has stopped. Hopefully, the city would have evacuated the city or areas of the city before the earthquake strikes. After its destruction has stopped most of the buildings are reduced to ruins and most people are homeless for a time. They are forced to take refuge in any churches, schools, or other community buildings, until the damage can be repaired. Even your money can be greatly effected by an earthquake. The whole city is destroyed, the banks would be destroyed, and your money would be lost.
But not all these earthquakes are considered ‘bad’. When earthquakes occur in unpopulated areas, it does not have the chance to destroy a city, only the landscape. So when an earthquake is created, it could shape the land causing cracks and rocks to shift, cliffs to form and even things like underwater valleys. Some earthquakes have created some of the greatest natural landmarks in the world. So depending on where the earthquake occurs, it could be beneficial, or bad.
Conclusion for Earthquakes:
You cannot stop earthquakes, but we can learn more, in hopes of discovering ways to protect ourselves from them. There are a few ways we could help prevent some damage of earthquakes in the future. Many buildings are constructed in areas of earthquake risk. If a building is being constructed in a city that has experienced earthquakes, new plans and building materials should be used to strengthen the building. Recently, materials like this have been invented, such as a combination of steel and rubber plates on buildings to absorb the shock of the earthquake. Another easy safety thing for earthquakes is for the government of a city to invest in a proper seismograph centre, and make sure there is always at least one person monitoring it in case of an earthquake. Simple precautions are the most effective way to minimize earthquake damage.