In the first minutes after the start of the eruption in 2018, the volcano Krakatau generated a tsunami with a height of 100 to 150 meters. By the time the coast reached the wave, it managed to decrease to 5-13 meters and caused the death of 427 people, but there could have been much more victims. This is stated in a study by Ocean Engineering.
To study the effects of the eruption, scientists used computer simulation. The results showed that in the first minutes the tsunami reached a height of up to 150 meters due to a large amount of rock falling into the water
According to researchers, in the period after 6-9 minutes after the eruption in the water, the whole side of the volcano sharply turned out to be from 150 to 170 million cubic meters of rock. This caused a wave up to 150 meters high and up to two kilometers long. Scientists calculated that the tsunami energy at the initial stage was equal to an earthquake of magnitude six.
After formation, the wave began to quickly dissipate under the action of friction and gravity, creating an underwater landslide. At the same time, at the time of the collapse on an uninhabited island a few kilometers from Krakatau, the tsunami was still very massive – 80 meters high. Five kilometers from the volcano, the wave weakened to 50-70 meters.
By the time of the collapse on the shores of Java and Sumatra, the height of the tsunami ranged from 5 to 13 meters, however, even this was enough to cause serious damage to residents and cause death of 427 people. Ocean Engineering will transmit the research results to the Indonesian authorities so that they can develop a new plan to respond to such tsunamis.
The Krakatau volcano erupted on December 22, 2018 and lasted about two minutes. The previous Krakatau eruption, which led to mass casualties, occurred in 1883, when the volcano caused a 42-meter tsunami, then 36 thousand people died.