Tsunamis are large ocean waves that are primarily caused by underwater earthquakes. During an earthquake, there is a sudden release of energy underneath the Earth`s surface, which causes the ocean floor to move. This movement displaces large amounts of water, leading to the creation of a tsunami.

Option 2, earthquakes, is the correct answer. This is because tsunamis are indeed caused by earthquakes, specifically those that occur underwater. These earthquakes cause the displacement of water, resulting in the formation of a tsunami.

Option 1, hurricanes, is incorrect. While hurricanes can cause storm surges, which are elevated water levels along coastlines, they are not responsible for the creation of tsunamis. Tsunamis are generated by the vertical movement of the ocean floor, whereas hurricanes are large-scale weather systems that develop over warm ocean waters.

Option 3, undersea landslides, is also incorrect. While undersea landslides can theoretically trigger a tsunami, they are not a common cause. Tsunamis are predominantly caused by the movement of the Earth`s tectonic plates during an earthquake.

Option 4, volcanic eruptions, is incorrect as well. Although volcanic eruptions can generate tsunamis in certain instances, they are