Earthquakes

• Earthquakes are the shaking, rolling or sudden shock of the earth’s surface.
• Earthquakes are the Earth's natural means of releasing stress.
• Earthquakes cannot be predicted, although scientists are working on it.
• If you throw a stone in a pond of still water, a series of waves are produced on the surface of the water, these waves spread out in all directions from the point where the stone strikes the water.
• Any sudden disturbances in the earth’s crust may produce vibration in the crust which travel in all directions from the point of disturbances.
• Focus is the point on the fault where rupture occurs and the location from which seismic waves are released.
• Epicenter is the point on the earth’s surface that is directly above the focus, the point where an earthquake or underground explosion originates.
• A Fault line is the surface trace of a fault, the line of intersection between the earth’s surface.
• Fault plane are the cracks or sudden slips of the land.
• A Fault scrap is the topographic expression of faulting attributed to the displacement of the land surface by movement along faults.
• The primary cause of an earthquake is faults on the crust of the earth.
• A Fault is a break or fracture with two blocks of rocks in response to stress.
• Earth scientists use the angle of the fault with respect to the surface (known as the dip) and the direction of slip along the fault to classify faults.
• Normal fault: a dip-slip fault in which the block above the fault has moved downward relative to the block below.
• Body waves are further divided into primary (P) waves and secondary (S) waves.
• A right-lateral strike-slip fault is one on which the displacement of the far block is to the right when viewed from either side.
• S-waves move in all directions from their source.
• Seismic waves produced due to earthquakes are divided into two major types: body waves and surface waves.
• P-waves are faster than S-waves.
• Body waves travel through the interior of earth as they leave the focus.
• S-waves move forwards and backwards as they are compressed and decompressed.
• A left-lateral strike-slip fault is one on which the displacement of the far block is to the left when viewed from either side.
• Volcanic causes of earthquakes include volcanic eruptions which produce earthquakes.
• Surface causes of earthquakes include great explosions, landslides, slips on steep coasts, dashing of sea waves, avalanches, railway trains, heavy trucks, and some large engineering projects.
• Primary Waves (P-waves) are high frequency, high wavelength, and move through both solids and liquids.
• Thrust (reverse)fault: a dip-slip fault in which the upper block, above the fault plane, moves up and over the lower block.
• Secondary Waves (S-waves) are high frequency, high wavelength, and cannot move through liquids.
• Some major causes of earthquakes are surface causes, volcanic causes, and tectonic causes.
• The first P-wave to arrive after an earthquake is the S-wave.
• Tectonic causes of earthquakes are structural disturbances resulting in the parts of the lithosphere.
• During a disaster, it's important to stay calm, switch on the transistor radio and obey instructions.
• Eat something during a disaster, as it will make you better and more capable of helping others.
• Do not walk around the streets to see what is happening during a disaster, instead keep the streets clear so rescue vehicles can access the roads easily.
• Landslides are a common occurrence during disasters, causing damage to property and injuring people.
• Do not rush and try not to worsen the situation during a disaster.
• Soil liquefaction is a phenomenon that occurs during disasters, causing damage to infrastructure and making it difficult for rescue teams to access the affected areas.
• If you are aware of people who have been buried, tell the rescue team during a disaster.
• Damage to high rise building in Bhuj during a disaster.
• Water pipes, sewers are disrupted during disasters, causing economic activities like agriculture, industry, trade and transport to be severely affected.
• Tsunami and floods are natural disasters that can occur during disasters, causing widespread destruction and loss of life.