Question

1. figure 5.1 shows earth’s major tectonic plate boundaries. the diagram shows the direction of movement.

fig. 5.1
a) with reference to fig. 5.1, name the type of tectonic plate boundary
between the nazca plate and the south american plate 1
between the indian plate and the african plate 1
b) explain how an underwater earthquake can lead to the formation of a tsunami.
2

1. figure 6.1 shows the location of the moon relative to the earth.

fig. 6.1
a) on fig. 6.1, write the letter x on the earth to show a location that would have a very high tide. 1
b) on fig. 6.1, write the letter s to indicate the sun’s position that would cause a spring tide when the moon is in the position shown. 1
name the force exerted by the moon and sun that affects earth’s ocean levels. 1

Explanation:

Part 5a (Nazca and South American Plate):

The Nazca plate and the South American plate interaction is a convergent boundary (specifically ocean - continental convergence, where the oceanic Nazca plate subducts beneath the continental South American plate).

Part 5a (Indian and African Plate):

The Indian plate and the African plate interaction is a divergent boundary, as these plates are moving apart from each other.

Part 5b:

An underwater earthquake occurs due to the sudden movement of tectonic plates. This movement displaces a large volume of water. The displaced water then moves outward in the form of waves (tsunami waves). As these waves approach the shore, their speed decreases and their height increases significantly, which can lead to the inundation of the coastline.

Part 6 (Force affecting tides):

The force exerted by the Moon and the Sun that affects Earth's oceanic levels is the gravitational force. The gravitational pull of the Moon (and to a lesser extent the Sun) causes the water in the oceans to bulge, resulting in tides.

Answer:

5a (Nazca - South American Plate): Convergent (Subduction) Boundary

5a (Indian - African Plate): Divergent Boundary

5b: Underwater earthquake displaces water, creating waves that grow in height near shore, inundating land.

6: Gravitational Force (from Moon and Sun)