What Causes Earthquake: Kids Special

Have you ever gotten a shiver down your spine after a sudden shaking and rumbling of the earth beneath your feet? It’s an earthquake, havoc wreaked underground. From the secret movements of massive plates deep within the Earth to the sudden energy bursts that produce seismic waves, earthquakes are nature’s way of showing its enormous power.

Buckle up as we embark on an intriguing journey to untangle the puzzle of the causes behind these tumbles.

What is an Earthquake

An earthquake is an intense and sudden shaking of the Earth’s outer layer, also called the crust. It’s like an underground dance party, rocking and moving the surface. On a serious note, an earthquake is a natural phenomenon caused by the sudden release of energy, creating seismic waves that radiate outwards from the earthquake’s origin. It’s nature’s own way of shuffling and rearranging its plate pieces deep beneath the mysterious ground.

Before and after the “real shaking” of the Earth’s surface, there may occur low-intensity earthquakes known as foreshocks and aftershocks, respectively. You will never identify a foreshock until you are hard hit by the main earthquake!

More than 80% of earthquakes shaking the ground occur in the Ring of Fire—one of the most seismically active areas in the Pacific Ocean, where many tectonic plates mingle. Earthquakes also shake the Mid-Atlantic Ridge and regions along several continental fault lines, such as the San Andreas Fault in California.

Now, let’s understand two common terms that come along with earthquakes. 

Seismic Waves

Seismic waves are the tremblings that travel through the ground during an earthquake. These waves carry the energy released during the Earth’s upheaval and cause the outer layer to rumble. You will see seismic waves to be more powerful at the center of the origin of an earthquake and gradually lose their power as they go further. Seismic waves can travel 20 times faster than sound!

Aftershock

A massive earthquake is often followed by smaller earthquakes. It occurs in the same place as the main earthquake and results from the crust trying to adjust to the effects of the main tremor.

What Causes Earthquakes?

Before you dive into the catalysts that make the Earth rock ‘n’ roll, let’s get a quick glimpse of what makes up the floor beneath your feet! The Earth consists of four layers: the crust, the mantle, the outer core, and the inner core. The solid outer layer, known as the lithosphere, springs into existence when the crust and mantle have a grand mingling! This shell—more like an eggshell—seems like a stony jigsaw puzzle with some pieces spread across countries, even continents! Below it is the outer core—a super-hot liquid mixture of iron and nickel that keen adventurers call the Earth’s own lava lamp! Finally, comes the inner core. Sitting deep, 2000 miles down at the Earth’s center, the inner core is made up of a sizzling iron ball, baking at a staggering 9,000° Fahrenheit!

Now, let’s get into what you are waiting for. What are the underlying causes of earthquakes? In short, the Earth shakes as the pieces of lithosphere, known as tectonic plates, trigger the Earth’s crust to release energy by constant movement. These massive rock slabs are constantly changing positions due to the axial rotation of the Earth and the hot liquid mantle underneath. When these plates collide, slide past, or converge with each other, they can cause the crust to fracture, creating faults. The movement of tectonic plates keeps building up stress along these faults. This phenomenon continues for a long time, accumulating more and more energy. When the energy gets too big for the ground to hold, and there is no movement along the fault lines, the accumulated energy gets released in the form of seismic waves. These seismic waves pass through the ground and generate vibrations that we call earthquakes.

How Long Do Earthquakes Last?

Earthquakes – the ground’s wiggly wobbles – don’t stay long. They stay for a few seconds, no more than 30–40 seconds, and go away wreaking havoc! The official longest and one of the strongest earthquakes ever recorded in the history of humankind was the Sumatran-Andaman earthquake that occurred in 2004 and lasted for 8–10 minutes. Epicentered off the west coast of northern Sumatra, Indonesia, in the Indian Ocean, this seismic salsa triggered a series of calamitous tsunamis along the coasts of 14 countries, with Indonesia being the hardest hit. Sumatran-Andaman earthquake on the coast of Indonesia, which caused shaking that was reported to last between eight and ten minutes.   

Effects of an Earthquake

Let’s go through what effects these tremors beneath our feet can have:

1. Ground Shaking: The most evitable effect is the shaking of the ground. Regions closer to the epicenter of the earthquake experienced stronger shaking compared to farther regions. Other factors influencing the intensity of an earthquake are the magnitude, duration, and depth of the earthquake, local geology, etc.
2. Damage to Man-Made Structures: Strong earthquakes can demolish infrastructure, roads, bridges, and human habitats, causing significant financial strain on governments. The extent of the damage can be extensive if structures are not designed and built following standard building codes.
3. Landslides and Avalanches: A steeper area hard hit by an earthquake may experience landslides and avalanches. As the ground shakes, the slopes get destabilised causing soil and rocks to slide downward.
4. Tsunamis: The most daunting and destructive havoc caused by an earthquake is tsunamis—a series of large waves caused by the displacement of water in the ocean or sea. These massive ocean waves sweep ashore, inundate a large area, and can even cause the death of humans. 

You can even see cliffs thrusting up, rivers changing direction, or ground having huge cracks due to a strong earthquake.   

How Do We Measure Earthquakes?

Since earthquakes occur due to seismic events, scientists use seismomenometer to measure the magnitude of an earthquake. With it, you will get seismic waves plotted in a series of zigzags.

This data is then used to find out the magnitude of the earthquake, usually expressed on the Richter scale. Invented by Charles F. Richter in the 1930s, this scale allows scientists to represent the energy an earthquake releases numerically. These readings are later used to figure out the time, location, and epicenter of the tremor. To determine the magnitude of very large earthquakes, the moment magnitude scale (Mw) is often preferred for its higher accuracy compared to the Richter scale. However, they are yet to predict when and where an earthquake will occur.

How to Survive an Earthquake

No matter where you stay, you can fall prey to a massive earthquake at any time! Don’t fret, taking some preventive measures can keep you safe during that tough time: 

• During an Earthquake: An earthquake can cause a disaster in a few seconds. If you are hit by an earthquake, keep calm and keep the following steps in mind:
• Drop: Don’t keep standing during an earthquake. Bend down on your hands and knees and proceed toward your shelter by crawling. 
• Cover: You can use your study table, bed, or desk as a safe place and cover your head underneath it. If you find no furniture, take shelter under a beam of a wall with your hands covering your head. 
• Maintain your grip: If you’ve taken shelter under furniture, hold your grip on it with a hand and move along with it if it’s moving. Stay in this place until the earthquake ends. 
• After an Earthquake: Listen to news to keep yourself aware of any instruction from the government or local authority. Don’t fret and take precautionary measures if you feel aftershocks.