Earthquake Definition

Whenever Earth's surface shake due to the release of energy in the lithosphere layer of the planet and results in seismic waves, it is referred to as an earthquake. Earthquakes range from too weak to extremely strong can and do take place. Many earthquakes have occurred and haven't even been felt, and many have damaged many lives. An earthquake is also known as a quake, tremblor, or tremor. These earthquakes can also become a reason to cause landslides. Seismic activity refers to an earthquake's type, size, and frequency in a particular period. Whenever an earthquake's epicenter occurs on or near the offshore, it causes a tsunami. An earthquake can also be defined as a seismic event caused by either humans or nature, which results in the generation of seismic waves. Rupturing geological faults by activities such as mine blasts, volcanic eruptions, nuclear tests, etc., often causes earthquakes. Its starting point is known as the hypocenter or focus. Also, the point directly above the hypocenter on the ground is known as the epicenter. Wherever there is enough elastic strain energy stored, tectonic earthquakes occur. When talking about earthquakes, we often imagine broken land surfaces. However, it is untrue many times. Earthquakes do not always do this; whenever they do, their slip is called to create an offset. Horizontal offset is known as heave, and that vertical one is known as throw. The actual measure of a fault over time, velocity, and acceleration is known as a fling.

Seismic Energy

The energy produced by seismic activities is known as seismic energy. Seismic energy is spread across basically in three different ways:

• Compression waves, also known as P waves, and mostly sound as sound waves.
• Shear waves, also known as S waves, and mostly seen like waves in any shaken rope.
• Surface waves, also known as Love waves, often seem as resembled water waves.

P and S waves are body waves that go deep in the Earth before coming to the surface. P waves do not cause any damage or just negligible ones. S waves travel first and hold the capacity to cause damage. Surface waves cause the maximum amount of damage and travel slowly compared to others.

Faults

Earthquakes occur in three different forms based on different faults. Mainly, three faults exist Normal fault, Reverse fault, and Strike-slip fault.

• Normal faults take place in the locations where the crust extends. It is a downward movement. Earthquakes aligned with these faults are generally less than 7 in magnitude.
• Reverse or thrust faults take place in the locations where the crust shortens. These faults include upward movement. Earthquakes associated with such faults are usually of 8 or more magnitude.
• When the sides of the faulting slip, forming steep structures are referred to as strike-slip faults. They involve sideways motion. These faults can lead to the creation of earthquakes having 8 as their magnitude.

When combining these faults and their movements, an oblique slip takes place.

Damage caused by earthquakes

There are different ways in which earthquake causes damage to people and property.

• Old and modern buildings are at a high risk of getting damaged due to shaking.
• A ground offset can cause damage to tunnels, highways, railroads, powerlines, etc.
• Liquefaction also happens when a solid is turned into mud due to shaking.
• Aftershocks completely vanish the structures which were previously destroyed by the main shock.
• Subsidence can lead to the disruption of lifelines and harbors.

Steps to be taken

One must know the steps to protect oneself in such a disaster. A roaring sound slowly getting louder, a gentle roaring sensation growing violent over time, or extreme shaking not letting you stand indicates the onset of an earthquake. Usually, collapsing buildings and heavy materials cause fatal injuries to people, making it necessary for the population to take steps to protect themselves. Generally, the place under the study table is considered a safe spot.

• Drop: Get down on your hands and knees to protect yourself.
• Cover: Cover yourself and place one of your arms and hand over your head and neck. Also, look for nearby tables to cover yourself.
• Hold: Hold in the same position until the shaking stops.

Tips to remember while preparing for an earthquake

Know the signs- It is very important to know the signs indicating an earthquake's start. Before the start of an earthquake, a roaring or rumbling sound is made, which gets louder within no time. It can also be a rolling sensation that grows violent afterward or a violent jot occurring suddenly, which after some seconds, leads to shaking, making it difficult for the beings to stand even properly.

Identify the safe spots- After identifying the onset of an earthquake, it gets important to know the safe spots to reach. Place under the table is considered the best reach during such situations, or cover the head with a pillow in the absence of this best position.

Create and practice plans- Always draft plans about what to do in these situations and conduct a mock drill. Adopting the proper practices might save yourself and your friends from such disasters.

Create the emergency supply kit:- There needs to be enough stock of items, at least for 3 days, needed in emergencies. It should include a first aid and supply kit, water, and food. Also, there should be a proper list of important information and a folder of crucial documents like contact information, aadhar card, birth certificate, property-related documents, passport, medical information, etc. Store all your information in a waterproof folder.

Tips to make sure to ready your home for such hazards

• Secure the items which are potential hazards and hold the capacity to harm someone.
• Sliding bolts can be installed to secure cabinet doors.
• Heavy electrical appliances like water heaters, stoves, washing machines, etc., should be secured by metal strapping or some wire or cable.
• Secure heavy mirrors and pictures over beds, chairs, and other places with some wire through eye screws.
• Know where the utilities are and how to shut them when required. Also, teach your family members, friends, and children the same.

Create evacuation plans

As said earlier, there exist different strengths of earthquakes. So, you may have to leave the area in times of disastrous earthquake or if an earthquake hits so hard. Therefore, planning, creating, and practicing an evacuation plan is necessary.

• Take time from your busy schedule, and sit with your family to draw, discuss, and decide on an evacuation plan for your home.
• Try to make a second way or door to escape in each room and area. Also, place the essentials like rope and ladder in a particular area where access to these materials is easy.
• Decide the spot where emergency supply kits, like water, first aid, food, and others, and fire extinguishers, are located.
• Mark the location where switches and valves would be set so they can be turned off easily when needed.
• Be aware of flood-zone-related information if living near dams or flood-prone areas.
• Set a location to conduct your family meeting outside your house in times of emergency.