Student Projects/Earthquake

An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth, resulting from the sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to toss people around and destroy whole cities. The seismicity, or seismic activity, of an area is the frequency, type and size of earthquakes experienced over a period of time. The word tremor is also used for non-earthquake seismic rumbling. An earthquake is a violent movement of the rocks in the Earth's crust which create waves of energy travelling through the Earth. Earthquakes are usually quite brief (and even somewhat repeated itself, known as an aftershock), but may repeat over a period of time. The study of earthquakes is called seismology. Earthquakes usually occur where tectonic plates are in constant motion, in which these areas of constant motion (or violent motion) are usually at the edges of the plates. For example, several and several earthquakes have been recorded in the Western part of South America due to the constant motion between the South American plate and the Nazca plate. Earthquakes usually occur on faults, which are breaks in the Earth's crust formed by the sliding, pushing, or pulling of tectonic plates.

An earthquake is the sudden shaking or movement of the Earth's surface caused by the release of energy from the Earth's crust. This energy radiates in the form of seismic waves, which travel through the Earth and can cause damage to buildings, roads, and landscapes. Earthquakes are natural phenomena that can range from small tremors felt by few to devastating events resulting in significant loss of life and property.

The Earth's crust is divided into large sections called tectonic plates. These plates are constantly moving, and when they collide, slide past, or pull away from one another, stress builds up along faults (cracks in the Earth’s crust). When the stress exceeds the strength of the rocks, it is suddenly released, causing an earthquake.

• **Tectonic movements** – Most earthquakes occur due to tectonic plate interactions.
• **Volcanic activity** – Some earthquakes occur near active volcanoes.
• **Human activities** – Activities such as mining, dam building, and underground nuclear testing can also induce earthquakes (known as induced seismicity).

Caused by the movement of tectonic plates. These are the most common and destructive type.

Occur due to volcanic eruptions or magma movement beneath the surface.

Small-scale tremors that occur due to underground cave collapses or mine explosions.

Man-made, caused by nuclear explosions or large-scale chemical detonations.

Earthquakes release energy in the form of **seismic waves**, which travel through the Earth's surface and interior.

• **P-waves (Primary waves)** – Travel fastest; compress and expand material.
• **S-waves (Secondary waves)** – Slower; move material up and down or side to side.
• **Surface waves** – Travel along the Earth’s surface; responsible for most destruction.

Earthquakes are measured based on their **magnitude** and **intensity**.

It is the amount of energy released during an earthquake, measured using instruments like the **Richter Scale** or **Moment Magnitude Scale (Mw)**.

• Richter Scale:

 - 1.0–2.9: Micro
 - 3.0–3.9: Minor
 - 4.0–4.9: Light
 - 5.0–5.9: Moderate
 - 6.0–6.9: Strong
 - 7.0–7.9: Major
 - 8.0 and above: Great

Describes the effects of an earthquake on people, buildings, and landscapes, measured using the **Modified Mercalli Intensity (MMI)** scale.

The Earth is divided into seismic zones based on past earthquake occurrences and plate boundaries.

• **Pacific Ring of Fire** – Most active seismic belt (includes Japan, Indonesia, west coast of the Americas).
• **Himalayan Belt** – Includes Northern India, Nepal, and parts of Pakistan.
• **Mid-Atlantic Ridge** – Undersea seismic activity zone.

• Japan
• Indonesia
• Nepal
• India
• Turkey
• Mexico
• Chile
• Iran
• United States (especially California and Alaska)

Earthquakes can have severe and widespread consequences depending on their magnitude and location.

• Ground shaking
• Surface rupture
• Ground displacement

• Landslides
• Tsunamis (in coastal areas)
• Fires due to broken gas lines
• Soil liquefaction
• Collapse of buildings and infrastructure
• Economic loss and displacement of people

• **2004 Indian Ocean Earthquake** – Magnitude 9.1; caused a devastating tsunami; over 230,000 killed.
• **2011 Japan Earthquake (Tohoku)** – Magnitude 9.0; led to Fukushima nuclear disaster.
• **2015 Nepal Earthquake** – Magnitude 7.8; over 9,000 deaths.
• **1906 San Francisco Earthquake** – Massive destruction and fire.
• **2001 Bhuj Earthquake (India)** – Magnitude 7.7; more than 20,000 killed.

Being prepared can significantly reduce the loss of life and damage caused by earthquakes.

• Construct earthquake-resistant buildings.
• Identify safe spots like under sturdy tables or against inside walls.
• Keep emergency kits with food, water, flashlight, and first-aid supplies.

• "Drop, Cover, and Hold On"
• Stay away from windows and heavy furniture.
• Do not use elevators.

• Check for injuries and provide first aid.
• Watch out for aftershocks.
• Evacuate if there is structural damage or a tsunami warning.

Earthquakes cannot be predicted accurately, but modern technology helps in early detection and warning.

• **Seismographs** – Detect seismic waves and record earthquakes.
• **GPS and satellite data** – Track crustal movements.
• **Early warning systems** – Used in Japan and Mexico to alert people seconds before strong shaking arrives.

Advancements in geoscience and engineering help minimize earthquake damage:

• Design of seismic-resistant buildings
• Ground motion simulations
• Hazard zoning and land-use planning
• Real-time monitoring by geological agencies (like USGS, IMD)

Earthquakes are powerful natural phenomena that occur due to movements within the Earth’s crust. While they are unpredictable, understanding their causes, effects, and preparedness measures can help reduce their impact on society. Through science, technology, and public awareness, the risks associated with earthquakes can be significantly mitigated.