10 – 20 meters
Explanation
Tsunamis are seismic sea waves generated by the sudden displacement of a large volume of water. This displacement is most commonly caused by undersea earthquakes in subduction zones, where one tectonic plate slides beneath another. The vertical movement of the seafloor during such an event lifts the water column above it, creating a wave.
Detailed Analysis
The 2004 Indian Ocean Tsunami was triggered by a massive undersea megathrust earthquake (magnitude 9.1–9.3). The geological mechanism involved the Indian Plate subducting (thrusting) beneath the Burma Plate.
- The earthquake caused a rupture along the fault line that was approximately 1,200 to 1,300 kilometers long.
- This sudden tectonic movement resulted in the ocean floor being vertically displaced by approximately 10 to 20 meters along the fault line.
- This massive vertical rise of the seabed displaced trillions of tons of water, generating the devastating tsunami waves that radiated across the Indian Ocean.
Key Takeaway: A tsunami is generated only when there is a vertical displacement of the ocean water column; horizontal movements of plates (strike-slip faults) generally do not generate significant tsunamis.