Teknologi.id - On December 22, 2018, a tsunami hit the west coast of Banten and the southern coast of Lampung, Indonesia. The Earthquake and Tsunami Information System managed by the Meteorology, Climatology and Geophysics Agency did not detect any tectonic earthquake activity.
When there were initial reports of seawater on the coast, they considered it a tidal wave of effects from the full moon and bad weather. Only at 23.55 WIB, the agency corrected the news, that there was a tsunami caused by the volcanic activity of Mount Anak Krakatoa.
Earthquakes or earth shift isn't always causing Tsunami. A landslide from volcanic mountain activity can cause a tsunami. Without early warning, it is like a tectonic tsunami detector.
These tsunamis can occur at any time, and occur suddenly as a result of volcanic avalanches which cause the sudden transfer of a large volume of water. So that it causes very fast waves like a jet to the coast. What then happens is the phenomenon we call a Tsunami event.
The Process of a Tsunami Due to Volcanic Activity
Volcanic activity or underwater volcanic mountains can cause landslides, causing large waves. The fall of the Vulcanic avalanche material that falls into the sea causing this wave. So that causes a very large volume of water.
This tsunami wave usually has a length of hundreds of kilometers, but with a height that is not too high at all. These waves cross the ocean with a jet-like speed or around 640-960 Km/hour.
Then there was 'Shoaling' which is a process where there is a high increase in a wave due to the waves entering more shallow water. Wave height can increase more than twice the initial amplitude.
Because of the change in depth, changes in wave speed occur. The speed of the wave decreases, so it is in a stationary position. By increasing energy density, will balance this situation. Increased energy density is what causes the increase in wave height.
So that high tide reaches the coast as a prefix. After that, the sea will recede, and return with a larger wave. This process occurs more than once, and this is a phenomenon that is not a large wave that we know as a Tsunami.
We can conclude that Tsunami occurs not only due to tectonic activity but can also be caused by volcanic activity. And of course, we also do not consider the activities of volcanic mountains that are still active. Of course, we have to be wiser in acting, not only because we are comfortably enjoying the atmosphere. We don't pay attention even if we don't care about the surroundings.
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