Volcano-triggered tsunami toll climbs to 222 in Indonesia

Volcano-triggered tsunami toll climbs to 222 in Indonesia

News:

Indonesian tsunami strikes without warning due to landslide on Krakatau volcano

Facts:

• As per the scientist, underwater landslide could be the leading theory which might have triggered the killer waves.
• Underwater landslide when occur, it pushes land into the ocean and displaces the ocean surface causing the vertical displacement of water.
• This is the second major tsunami that Indonesia has dealt with in the past few months. In late September, an earthquake triggered a huge tsunami that hit the Indonesian city of Palu, killing around 2,000 people
• A tsunami can also be caused by other things that move vast amounts of water, from storms to underwater landslides, which experts think is the most likely explanation for what happened in the Sunda Strait.
• The fact the tsunami was triggered by a volcano, and not by an earthquake, may be the reason why no tsunami warning was signaled.

Additional facts:

What is a tsunami?

• A tsunami is a series of great sea waves caused by an underwater earthquake, landslide, or volcanic eruption. More rarely, a tsunami can be generated by a giant meteor impact with the ocean
• This earthquake creates an explosive vertical motion that can displace the overlying water column, creating a rise or fall in the level of the ocean above. This rise or fall in sea level is the initial impulse that generates a tsunami wave.

Characteristics of a tsunami:

• Tsunamis have long wavelengths – Tsunami waves may have wavelengths up to hundreds of kilometers between wave crests
• The speed of tsunami waves depends on ocean depth rather than the distance from the source of the wave
• As a tsunami approaches land, the size increases – The speed and size of a tsunami is controlled by water depth. In the deep ocean tsunami waves may be unnoticed by ships or from the air. As the wave approaches land it reaches shallow water and slows down.

The Tsunami Warning System (TWS)

• In the Pacific, comprised of 26 member countries, monitors seismological and tidal stations throughout the Pacific region. The system evaluates potentially tsunamigenic earthquakes and issues tsunami warnings.

The Indian Tsunami Early Warning Centre (ITEWC)

• Established at Indian National Centre for Ocean Information Sciences, (INCOIS – ESSO) Hyderabad, autonomous body under Ministry of Earth Sciences, is being upgraded continuously to provide tsunami advisories for the events occurring in the global oceans, though it has been recognized as one of the best systems in the world.