Test: Interior Of The Earth - 1 - UPSC MCQ

The point inside the Earth where the energy of an earthquake is first released is called the hypocenter, alternatively known as the focus of the earthquake. This is the initial point where the rocks along a fault break and the energy is released, leading to the generation of seismic waves. The hypocenter is located beneath the Earth's surface, and its corresponding point on the surface directly above is known as the epicenter.

The property of velocity causes earthquake waves to change direction as they reflect or refract when coming across materials with different densities. The velocity of waves changes as they travel through materials with different densities, with denser materials increasing the wave velocity.

The primary feature that sets apart the shadow zone of S-waves from the shadow zone of P-waves is the size of the shadow zone. The shadow zone of S-waves is notably larger than that of P-waves, extending beyond 105° from the epicenter.

Earthquake events are commonly categorized based on the intensity and magnitude of the shock they produce. The Richter scale measures the magnitude, which relates to the energy released, while the Mercalli scale gauges the intensity by considering visible damage.

Gravity anomalies provide valuable information about the distribution of mass in the Earth's crust. By studying gravity anomalies, scientists can gain insights into the variations in density and composition of materials within the Earth's crust. This data is crucial for understanding the geological structure and composition of the Earth's outermost layer.

Shield volcanoes are predominantly made up of basaltic lava, which is very fluid when erupted. This fluidity contributes to the gentle slopes of shield volcanoes. The fluid nature of basaltic lava allows it to flow more easily and cover larger areas compared to more viscous lavas like andesitic or rhyolitic lava. This lava type is responsible for the expansive, low-angle profiles characteristic of shield volcanoes.

Seismic activities play a crucial role in helping us understand the Earth's interior structure. By studying seismic waves generated by earthquakes and other sources, scientists can infer valuable information about the composition, density, and layering of materials beneath the Earth's surface. This data provides insights into the properties and behavior of the Earth's interior layers.

Magnetic surveys primarily offer information about the distribution of magnetic materials in the Earth's crust. By conducting magnetic surveys, scientists can map out the locations of magnetic minerals and materials within the Earth's crust. This data helps in understanding the geological composition and structure of the Earth's outermost layer in greater detail.

Flood basalt provinces are linked to the eruption of highly fluid lava that can flow for long distances, covering extensive areas with thick basaltic lava flows. These volcanic regions can be characterized by the outpouring of massive amounts of lava, leading to the formation of vast basalt plateaus and landscapes covered with layers of basaltic rock. The Deccan Traps in India are an example of a flood basalt province that has produced extensive lava flows, shaping the geological features of the region.

Sills and sheets are near-horizontal bodies of intrusive igneous rocks that are typically found at the top of anticlines in folded igneous country. These formations vary in thickness, with thinner deposits referred to as sheets and thicker ones as sills. Understanding the location and formation of sills and sheets is crucial in interpreting the geological history of a region.