Chapter 4, Problem 1QR

To determine

The map of an idealized tectonic plate and the earthquake hazards associated with each type of plate edge.

Answer to Problem 1QR

The map of an idealized tectonic plate contains three types of plate edges. The divergent motion causes small earthquakes, slide-past motion causes major earthquakes, and the convergent motion causes very large magnitudes of earthquake.

Explanation of Solution

Pictorial representation: Fig.1 represents a map of an idealized tectonic plate.

Fig.1: Map of an idealized tectonic plate

An earthquake is defined as a natural event which is caused by the sudden shaking of the surface of the earth. The occurrence of an earthquake is explained by the plate-tectonics theory, in which the lithosphere breaks into rigid plates that move away from, past, and into other rigid plates. This process is seen on the ground as individual faults, where the Earth ruptures and the two sides move past each other in earthquake-generating events.

The earthquake hazards that are associated with each type of plate edge are as follows:

(i) Divergent or pull-apart motion:

The divergent motion of tectonic plates occurs at the spreading centers. It causes the rocks to fail in tension, which results in the easy rupture of the rocks. It results in the yield of many small earthquakes.

(ii) Slide-past motion:

This motion occurs at the curved paths of Earth in the transform faults and causes the plates to slide and shear with each other. It results in causing major earthquakes.

(iii) Convergent or push together motion:

It occurs at the subduction zones and in continent-continent collisions, which causes the rocks to fail in compression. This motion stores immense amount of energy, which is released during very large magnitudes of earthquake.