a) A tsunami is a series of ocean waves caused by large-scale disturbances of the ocean, such as earthquakes, volcanic eruptions, or underwater landslides. These disturbances can displace a large volume of water, creating a series of waves that travel across the ocean, sometimes at very high speeds.
Tsunamis are characterized by their long wavelength, which means that they can travel great distances across the ocean without losing much energy. When a tsunami reaches the shore, its long wavelength causes the water to pile up into a very tall and powerful wave, which can cause widespread damage and destruction.
b) An earthquake is a sudden and violent shaking of the Earth’s surface, caused by the movement of tectonic plates. Tectonic plates are large pieces of the Earth’s crust that move and interact with each other, sometimes creating friction and tension that build up over time. When this tension is released suddenly, it can cause the Earth’s surface to shake and vibrate, resulting in an earthquake.
The Richter Scale is a numerical scale used to measure the magnitude or strength of an earthquake. It is based on the amplitude of the seismic waves produced by the earthquake, as measured by seismographs. The scale is logarithmic, meaning that each whole number increase represents a ten-fold increase in the amplitude of the seismic waves.
The earthquake in Pakistan dated 26 October 2015 had a magnitude of 7.5 on the Richter Scale. Its epicenter was located in the Hindu Kush mountain range in Afghanistan, but it was felt across Pakistan and northern India. The earthquake caused significant damage and loss of life, particularly in remote and mountainous areas where many homes and buildings were not built to withstand seismic activity.