What is an Earthquake?
‘The earthlings were probably seated comfortably on their couch, maybe sipping their morning brew, or reading the day’s chronicle, while in another pole of the earth some were hitting their bed after a long day’s work, this is when the earth thought to quake!’ In our life, every single one of us has undeniably experienced earthquakes. The earth’s tremor makes us alarm instantly. We rush to find the safe spot thus, honestly, we are terrified of the shakes.
Have you ever wondered what causes earthquakes? Or more simply put, what exactly is an earthquake? In this context, we are going to discuss precisely this trembler known as an earthquake.
What is an Earthquake?
An earthquake can be defined as the sudden movement or the trembling that is felt on the Earth's tectonic plates, this creates a shake or vibration on the ground. This shaking caused by the earthquake can destroy the buildings and in worst cases can even break the Earth's surface. While sudden shakes underwater are known as tsunamis.
Earthquakes are caused by the disturbances in the balance of the earth. Earthquakes are also caused by the reactions which result from the invisible events that operate beneath the Earth's surface known as the earth’s crust.
What Causes Earthquakes?
In the study of social sciences, we previously have learned the chapter on earth’s crust. So, the layers of the earth are known as:
the inner core
the outer core
mantle
crust
We know that the crust and the top layer of the mantle are made up of thin skin which is layered on the surface of our planet earth.But, do you know the earth’s skin is not all a single piece? Rather, the skin is made up of many earthly pieces which give the structure like a puzzle. This puzzle-like piece covers the surface of the earth.Another amazing fact is these pieces of the puzzle keep on moving slowly moving around one another, it slides past one another and go on bumping into themselves. In geographic terms, these puzzle pieces are called the tectonic plates, and the edges of the plates are known as the plate boundaries. The plate boundaries are created by many faults, and most of the earthquakes around the world occur on these faults themselves.
How Does an Earthquake Occur?
The edges of these plates are quite rough, thus while bumping into each other, the edges get stuck while the rest of the plate keeps on moving. Finally, when the plate has moved quite far enough, the edges then create a vibrating motion and unstick on one of the faults, and then there causes an earthquake.
Effects of Earthquake:
Every phenomenon on this earth has a cause and effect. In the previous section we have studied the cause of the earthquake, now in this section, we will know about the effects of earthquakes.
1 Ground Shaking
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Ground shaking is the most common effect that happens during an earthquake. In fact, this is the first effect that indicates an occurrence of an earthquake. The shaking of the ground is a result of the passage of the seismic tremor which is caused through the ground. The seismic waves range from gentler type small earthquakes to incredibly violent or large earthquakes.
2 Ground Rupture
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Ground rupture is another destructive effect of earthquakes that is caused when due to the shakings of the earthquake a fault actually breaks the Earth's upper surface. Though this incident of ground rupture for an earthquake is comparatively very rare, there have been cases of it in most of the parts of California.
3 Landslides
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Landslides can also be caused due to earthquakes. Landslides happen both by the direct rupture and by the sustained shaking of the unstable slopes. These dangerous slides can easily destroy any buildings which come in their path. They also block roads, railroad lines, or take the hilltop homes down.
4 Tsunamis
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Tsunamis worldwide proved to be a grave hazard, particularly around the Pacific Ocean region. Tsunamis are actually a series of water waves that are caused when the seafloor makes movement vertically in times of an earthquake.
5 Fires
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Fires are another horrific effect that causes huge damage after the earthquakes. The ground rupture and liquefaction caused due to earthquakes can easily emit out the natural gas mains and the water mains, these both contribute to the ignition of fires which hinders the efforts to control them effectively.
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In the year 1994, Northridge faced an earthquake where water was pouring down the streets from broken water channels while at the same spot, and at the same time, the fire was blowing out of the ruptured channels.
Types of Earthquakes
The types of earthquakes majorly depend upon the region where it occurs and the geological structure of that region is also defined here. There are many different types of earthquakes, most basic and popular are these types:
Tectonic Earthquake
Volcanic Earthquake
Explosion Earthquake
Among these, the most common types of earthquakes are the tectonic type earthquakes which occur when the rocks in the earth's crust break because of the geological forces that are created by the motion of the tectonic plates.
The Volcanic types of earthquakes occur with a combination of volcanic activity. Among these is the collapse of earthquakes, which happen in underground caverns or mines.
Explosion earthquakes have resulted from the explosion of any nuclear or chemical devices.
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Earthquakes are being recorded by an instrument called seismographs. While the intensity of earthquakes is measured by the Richter Scale.
How Does a Seismograph Work?
The seismograph has a definite base structure that is being placed firmly in the ground, and then a heavy weight-like structure is hung freely. When an earthquake causes the ground to shake naturally, thus the base of the seismograph shakes in that effect, but the hanging heavyweight due to its load does not move. Instead, the spring or the string that is kept hanging from the weight absorbs all the movement. The difference in the position which is between the shaking part of the seismograph and the motionless part is then recorded on a white sheet of paper.
Magnitude of Earthquake
Here are some effects of earthquakes according to different magnitudes.
Magnitude Earthquake Effects
6.1 to 6.9 - Might cause a lot of damage in populated areas.
7.0 to 7.9 - This is a major earthquake with serious damage.
8.0 or more - Can destroy the whole community near the epicenter.
Did You Know?
Can scientists really predict earthquakes?
Absolutely not, and it seems that they can never predict them. They have tried a lot of ways to predict the earthquake but for one fault or the other, the procedure did not succeed.
Can really some animals or any mystic people tell when an earthquake is about to hit the earth?
The answer can never be a definite one. It is difficult for us to say whether some animals or people can actually predict an incoming earthquake.
Earthquakes are not Evil!
This is a fact that earthquakes never killed anyone. Rather this is the fault of our constructed weak and tall buildings which cannot bear the shakes. We have to understand, earthquakes are mindless and natural occurrences, we human beings are not the same!
Thus, we are now completely educated about earthquakes, why they happen, how they happen, and what their types are. Earthquakes are a natural phenomenon that causes different earthy structures. It erupts on its own and calms down on its own. All we need to make sure of is taking all the precautions while it hits.
FAQs on Earthquake
1. What exactly is an earthquake and what happens inside the Earth when one occurs?
An earthquake is the shaking of the Earth's surface that happens when there is a sudden release of energy in the planet's crust. This energy is usually released when massive rock bodies, known as tectonic plates, move and slide past one another. The point underground where the rock breaks and energy is released is called the focus, and this energy travels outwards as seismic waves, causing the ground to shake.
2. What are the main causes of earthquakes?
While the vast majority of earthquakes are caused by tectonic plate movement, other factors can also trigger them. The primary causes include:
- Tectonic Activity: The continuous movement of Earth's tectonic plates builds up stress along fault lines. When this stress is suddenly released, it causes an earthquake.
- Volcanic Eruptions: The movement of magma beneath a volcano can fracture rock and cause small to moderate earthquakes in the surrounding area.
- Human Activities: Large-scale activities like filling reservoirs, underground mining operations, or nuclear explosions can sometimes induce minor, localised tremors.
3. What is the difference between the epicentre and the focus of an earthquake?
The focus (also called the hypocentre) is the exact point *inside* the Earth's crust where the earthquake originates. In contrast, the epicentre is the point on the Earth's surface located directly *above* the focus. The shaking and damage are typically most severe at the epicentre because it is the closest surface point to the energy source.
4. How is the power of an earthquake measured and what does the number mean?
The power, or magnitude, of an earthquake is measured using the Richter scale. This scale is logarithmic, meaning for each whole number you go up, the ground shaking increases by 10 times. For example, a magnitude 7.0 earthquake is ten times more powerful than a 6.0. An instrument called a seismograph is used to detect and record the seismic waves to determine this magnitude.
5. Why do some parts of the world, like Japan or California, have so many earthquakes while others have almost none?
This is because earthquakes are not random. They primarily occur along plate boundaries, which are the edges where tectonic plates meet. Regions like Japan and California are situated on or very near these active boundaries, such as the Pacific 'Ring of Fire'. In contrast, areas located in the stable interior of a tectonic plate, far from any edges, experience very few earthquakes.
6. What are the most important safety tips to remember if you are caught in an earthquake?
The most crucial advice is to stay calm and follow the "Drop, Cover, and Hold On" rule. If you are indoors, drop to the ground, take cover under a sturdy piece of furniture like a heavy desk or table, and hold on until the shaking stops. Stay away from windows, glass, or anything that could fall. If you are outdoors, find a clear, open spot away from buildings, trees, and power lines.
7. Can scientists accurately predict when and where an earthquake will happen?
No, despite advancements in seismology, scientists cannot accurately predict the exact time, place, and magnitude of a future earthquake. They can, however, make long-term forecasts. By studying historical data and monitoring fault lines, they can identify seismic zones that have a high probability of experiencing an earthquake over a period of many years, which helps in creating building codes and preparedness plans.
8. Could an earthquake with a magnitude of 10.0 ever occur?
A magnitude 10.0 earthquake is considered extremely unlikely and perhaps impossible with Earth's current geology. The magnitude of an earthquake is linked to the length of the fault that ruptures. A magnitude 10.0 quake would require a fault line of enormous length to break all at once, something larger than any known continuous fault system on the planet. The largest earthquake ever recorded was a magnitude 9.5 in Chile in 1960.
