Closest to the epicentre
Explanation
An earthquake involves the release of energy from a specific point within the Earth's crust, known as the Focus or Hypocentre. The point on the surface vertically above the focus is called the Epicentre. The intensity of ground shaking and the resulting destruction are directly related to the distance from the source of energy release.
Detailed Analysis:
- At the Focus : The focus is the point of origin deep underground where the fault slip occurs. While this is where the energy is released, structural damage refers to destruction on the surface. Therefore, the focus itself is not the site of surface damage.
- Closest to the Epicentre : The epicentre is the first point on the surface to experience seismic waves. Since it is physically closest to the energy source (focus), the intensity of the waves is highest here. Consequently, the greatest damage to infrastructure and life is usually observed at or near the epicentre. As the distance from the epicentre increases, the energy of the seismic waves dissipates, reducing the severity of the damage.
- Deep inside the Mantle : The mantle is a layer beneath the crust. Damage assessment is relevant to the Earth's surface where human settlements exist.
- At the Antipodal Point : The antipodal point is the location on the Earth's surface diametrically opposite to the epicentre. Seismic waves are weakest at this point due to the vast distance traveled and energy attenuation.
Key Takeaway:
Seismic intensity is maximum at the Epicentre because it is the nearest surface point to the Focus; intensity and damage decrease as the distance from the epicentre increases.