What is a Earthquake?

Earthquakes are usually caused when underground rock suddenly breaks and there is rapid motion along a fault. This sudden release of energy causes the seismic waves that make the ground shake.

What causes earthquakes and where do they happen?

The earth has four major layers: the inner core, outer core, mantle and crust. The crust and the top of the mantle make up a thin skin on the surface of our planet.

But this skin is not all in one piece – it is made up of many pieces like a puzzle covering the surface of the earth. Not only that, but these puzzle pieces keep slowly moving around, sliding past one another and bumping into each other. We call these puzzle pieces tectonic plates, and the edges of the plates are called the plate boundaries. The plate boundaries are made up of many faults, and most of the earthquakes around the world occur on these faults. Since the edges of the plates are rough, they get stuck while the rest of the plate keeps moving. Finally, when the plate has moved far enough, the edges unstick on one of the faults and there is an earthquake.

Types Of Earthquakes

There are four different types of earthquakes: tectonic, volcanic, collapse and explosion

Tectonic Earthquake :- Is one that occurs when the earth's crust breaks due to geological forces on rocks and adjoining plates that cause physical and chemical changes.

Volcanic earthquake :- is any earthquake that results from tectonic forces which occur in conjunction with volcanic activity.

Collapse earthquake :- are small earthquakes in underground caverns and mines that are caused by seismic waves produced from the explosion of rock on the surface.

Explosion earthquake :- is an earthquake that is the result of the detonation of a nuclear and/or chemical device.

How to protect yourself in the case of earths quakes

Drop. Cover. Hold on.

In most situations, you can protect yourself if you immediately:

• DROP down onto your hands and knees before the earthquake knocks you down. This position protects you from falling but allows you to still move if necessary.

• COVER your head and neck (and your entire body if possible) underneath a sturdy table or desk. If there is no shelter nearby, get down near an interior wall or next to low-lying furniture that won’t fall on you, and cover your head and neck with your arms and hands.

• HOLD ON to your shelter (or to your head and neck) until the shaking stops. Be prepared to move with your shelter if the shaking shifts it around.

Tips to Reduce Earthquake Damage

Here are some other things you can do:

§ To prevent injuries from flying glass, apply safety film to windows and glass doors.

§ Anchor large appliances to walls using safety cables or straps.

§ Install ledge barriers on shelves and secure large, heavy items and breakables directly to shelves to keep them from falling.

§ Install latches on drawers and cabinet doors to keep contents from spilling.

§ Anchor filing cabinets and televisions to walls.

§ Hang mirrors and pictures with closed hooks.

§ Secure water heaters to wall studs with two metal straps.

How are earthquakes recorded?

Earthquakes are recorded by instruments called seismographs. The recording they make is called a seismogram. The seismograph has a base that sets firmly in the ground, and a heavy weight that hangs free. When an earthquake causes the ground to shake, the base of the seismograph shakes too, but the hanging weight does not. Instead the spring or string that it is hanging from absorbs all the movement. The difference in position between the shaking part of the seismograph and the motionless part is what is recorded.

Can scientists predict earthquakes?

No, and it is unlikely they will ever be able to predict them. Scientists have tried many different ways of predicting earthquakes, but none have been successful. On any particular fault, scientists know there will be another earthquake sometime in the future, but they have no way of telling when it will happen.

Did you know?

Elephants Rats and snakes can also show unusual movement patterns before earthquakes. In this way, the researchers discovered unusual behavioral patterns up to 20 hours before an earthquake. “The closer the animals were to the epicenter of the impending shock, the earlier they changed their behavior.

Valdivia Earthquake

On May 22, 1960, the most powerful earthquake in recorded history — magnitude 9.5 — struck southern Chile. The rupture zone stretched from estimates ranging from 500 kilometers to almost 1,000 kilometers along the country’s coast. The event was named after the city most affected by the quake, Valdivia.

The Valdivia earthquake left two million people homeless, injured at least 3,000, and killed approximately 1,655. The economic damage totaled more than $4.8 billion (adjusted for 2020 inflation).

The Valdivia earthquake triggered a massive tsunami that raced across the Pacific. Waves wracked coastal communities as far away as New Zealand, Japan, and the Philippines. In Hawai'i, the tsunami devastated the coastal town of Hilo, killing 61 people.

Japan Model

3 Ways Japanese Respond to an Earthquake

If you like videos more than reading, check out this 20-minute documentary about Japan’s earthquake systems.

1. Trains

Seismometers are placed on every train track to monitors seismic activity (earthquakes). When signaled, the system automatically engages the breaks, coming to a near halt in the time before the quake hits.

Saftey measures like guard rails have been added to prevent complete derailment and most tracks are built to sustain a swaying movement. Even a bullet train hurtling along at full-speed can come to a halt and keep its occupants safe.

2. Buildings

It’s a marvel of Japanese engineering that skyscrapers stay standing during an earthquake. Many have a counterweight system installed that swings with the movement of the building to stabilize it.

Smaller houses are built on flexible foundations that can absorb movement in 6 directions and diminish the effects of the quake. Elevators automatically shut down and have to be checked before they operate again. Gas, electricity and water lines turn off automatically when triggered, preventing fires, floods, and explosions.

3. People

Children are trained by their schools to deal with earthquakes from kindergarten. They do drills, learn not to panic, and gain experience in simulation machines. After an earthquake, an adult is required to pick up a child from school, just in case, there is damage to their home or family.

There is a calm ‘no panic’ attitude that everyone adopts during an earthquake. Even when scared, people will follow the protocols, ensuring the safest environment possible.

By:- Vedant Sonawane & Kunj Patil