Final answer:
Tsunamis are primarily caused by seismic activity, especially during undersea earthquakes at convergent plate boundaries or subduction zones and sea floor spreading. The 2004 Indian Ocean tsunami was triggered by a powerful earthquake, followed by devastating waves traveling at high speeds towards coastal areas. The correct answer is option b.
Step-by-step explanation:
Tsunamis are a series of waves in the ocean primarily caused by seismic activity such as earthquakes. These earthquakes typically occur at convergent plate boundaries or subduction zones, where one tectonic plate slides beneath another, potentially triggering these massive waves. The movement of plates can also cause volcanic eruptions and the creation of mountain ranges.
The 2004 Indian Ocean tsunami, one of the deadliest in history, was caused by an underwater earthquake that had the energy of thousands of atomic bombs. The earthquake generated waves that reached 30 meters high and traveled at high speeds, impacting coastal regions across several countries. In the case of the 2011 Tohoku earthquake in Japan, the tsunami it generated caused additional damage to nuclear facilities, leading to a serious nuclear incident.
Regarding the specific question the student has about causes of tsunamis, the answer is b. seismic activity.