Tsunami

Rationale: Submarine earthquakes occurring at subduction zones (convergent plate boundaries) cause sudden vertical displacement of the seafloor, generating the largest and most destructive tsunamis.

Rationale: In the deep open ocean, tsunamis have extremely long wavelengths (often >100 km) and very low amplitudes (often less than a meter), making them unnoticeable to ships.

Rationale: Tsunamis act as shallow-water waves because their wavelength is much greater than the ocean depth. Their speed is calculated as c = sqrt(gd), depending entirely on gravitational acceleration and water depth.

Rationale: The Pacific Ocean basin, surrounded by the circum-Pacific 'Ring of Fire', is prone to frequent subduction zone earthquakes, accounting for over 80% of global tsunamis.

Rationale: Run-up refers to the maximum vertical height above sea level that the water reaches onshore when a tsunami strikes.

Rationale: Before the main crest of a tsunami arrives, the trough often reaches the shore first, resulting in an abnormal and sudden retreat of seawater exposing the seabed.

Rationale: DART systems use seafloor bottom pressure recorders linked to surface buoys to detect pressure changes caused by tsunami waves in deep water and transmit data via satellite.

Rationale: Tsunamis are generated as a wave train (a series of waves). Interference patterns and varying refractory paths mean subsequent waves in the train are often much larger than the first.

Rationale: The 2004 Indian Ocean tsunami was caused by the massive Sumatra-Andaman megathrust earthquake off the coast of Aceh, Indonesia.

Rationale: Submarine landslides and volcanic collapses (such as Krakatoa in 1883) displace massive volumes of water, generating highly destructive local tsunamis, though earthquakes cause trans-oceanic ones.

Rationale: As water depth decreases, friction slows the front of the wave, compressing the wavelength while the wave height (amplitude) increases dramatically due to energy conservation.

Rationale: 'Tsu' means harbor and 'nami' means wave in Japanese, reflecting how fishermen would return to port to find their harbors destroyed even though they felt no wave in deep water.

Rationale: The Pacific Tsunami Warning Center (PTWC), operated by NOAA in Hawaii, is the primary operational center for Pacific basin tsunami alerts.

Rationale: Transform faults (horizontal sliding like San Andreas) and divergent boundaries (spreading centers) typically do not produce the massive vertical seafloor displacement required for large tsunamis.

Rationale: Inundation distance measures how far inland the water floods horizontally from the shoreline.

Rationale: Wind waves are surface phenomena whose motion decays rapidly with depth. Tsunamis have wavelengths so long that they act as shallow-water waves affecting the entire water column right down to the abyss.

Rationale: INCOIS, located in Hyderabad, operates the Indian Tsunami Early Warning Centre (ITEWC), providing advisories for the entire Indian Ocean region.

Rationale: The cataclysmic collapse and explosion of Krakatoa in August 1883 generated pyroclastic flows and caldera collapse that produced devastating tsunamis.