Consisting of the islands, some of which are volcanic islands, makes Indonesia as one of the most vulnerable countries affected by the tsunami volcanic. The eruption of Mount Krakatau in the Sunda Strait in 1883, which triggered a giant tsunami, be evidence of the geological condition of Indonesia's hyperactive.

Catastrophe of Krakatoa in 1883 have opened the eyes of the world that the combination of volcanic eruptions and tsunamis can be very lethal threat. This tsunami was the largest volcanic tsunamis and to have the most extensive ever recorded in history.

James E Begét, researchers from the Alaska Volcano Observatory (2000), mentions, in 250 years there have been 90 tsunamis caused by volcanoes, and 25 percent of them fatal impact on life. Tsunami caused by volcanic oldest identified occurred during the eruption of Mount Santorini in Greece in 1638 BC. The combination of volcanic eruptions and tsunami that allegedly destroyed the civilization of Crete.

The eruption of Mount Vesuvius in Italy in the year 79, which buried Pompeii, also followed by a tsunami. Large tsunamis also occurred in Japan, when Mount Unzen erupted in 1792. High waves are believed to occur because of avalanches when Mount Unzen erupted estimated at 55 meters, and killed more than 10,000 inhabitants.

Prasetya concussion, researchers from the Amalgamated Solutions and Research (ASR), research institutes in the field of tsunamis and natural disasters, said there are 18 volcanoes in Indonesia that could potentially cause a tsunami if it erupted. Of the 18 volcanoes that, only three volcanoes that have detailed data and monitored its development at this time. The third mountain is the Son of Krakatoa in the Sunda Strait, which causes tsunamis when erupted in 1883; Tambora in Sumbawa, erupted in 1815 when, and Banda Api in the Banda Sea.

In addition to the three mountains, some volcanoes which allegedly had caused a tsunami in the past, among them, is Rokatinda on Flores Island, which erupted in 1928; Space Island in 1889, Awu Island in 1856 and 1892, Island Gamkonora in 1673, and Gamalama Island in 1871.

Makian Volcano on Halmahera, Karangetan in Sangihe, and Una-Una in the Gulf of Tomini also allegedly been caused by the tsunami. In addition, a mountain of fire under the sea around the island of Weh also been sent to the Banda Aceh tsunami.

"Our knowledge of tsunamis caused by the eruption of the volcano is still very little because it had happened a very long time and the lack of records. Most of all, knowledge is derived from sediments tsunami," said Concussion.

According Concussion, potential tsunami which triggered the eruption of volcanoes in Indonesia is quite high because of the large island of active volcanoes or volcanoes that mountain body located in the ocean.

Lessons Krakatoa

Learning from the eruption of Krakatoa in 1883, the tsunami that followed the volcanic eruption can be more deadly. Height and reach of the tsunami waves caused by volcanic eruptions is equally high when compared with tectonic earthquake caused a tsunami. Krakatau tsunami reached an altitude of 30-40 meters along the west coast of the southern coast of Banten and Lampung.

Volcano expert from the Central Geological Survey, Sutikno Bronto, say, the tsunami caused by the eruption of Krakatoa in 1883 is one of the largest volcanoes ever done, so experts are racing to examine the cause of the tsunami. "Why cause a tsunami in 1883 and many casualties in the Strait of Sunda? Why on than just a lot of people died and burns?" Sutikno said.

So far, experts have not agreed on what caused the tsunami pascaletusan Krakatoa. "At least five hypotheses are made concerning how the tsunami happened," said Sutikno.

The first hypothesis, the tsunami was caused by debris. After the eruption of material thrown up, then fall down. "The fall of material into the sea is expected to form a tsunami," said Sutikno.

The second hypothesis states, has led to the eruption of Krakatoa in the ocean basins. Sea water entered into the caldera fill and then turned out to be a tsunami. Proponents of this theory among Yokoyama (1981).

Volcano avalanche in a particular direction (debris avalanche) is the third hypothesis. "When the eruption, the eruption of material out of the mountain sides, causing avalanches that caused the tsunami," said Indyo Pratomo, geologists from the Geological Museum in Bandung.

The fourth hypothesis, Krakatau tsunami caused by the heat that goes into clouds underwater. Rising sea temperatures caused by the sudden overflow of hot clouds caused a pressure change that triggered the tsunami.

The fifth hypothesis also mention Krakatoa tsunami caused by the hot cloud. The difference, hot clouds do not get into the water, but creeping above sea level. Propagation of heat clouds that triggered the tsunami waves. This opinion is supported by oceanographers and volcanoes of the University of Rhode Island, United States, Haraldur Sigurdsson and Steven Carey.

"This hypothesis is corroborated the testimony of people than just the burning heat clouds.'s Hot clouds spread over the sea water, while vines also trigger tsunamis," said Sutikno.

Anak Krakatau

Although still a controversy, the tsunami that hit the post-eruption of Krakatoa had been agreed upon as the biggest killer factor when the mountain erupted in 1883 and killed 36,000 people. Seeing these dynamics, the tsunami is an important factor that must be seen in mitigating Anak Krakatau is currently growing rapidly and form a body resembling ancestral mountain, Krakatoa.

Children grow up in the middle of the former Krakatau eruption of Krakatoa, 1883. In 2008, Anak Krakatau has reached a diameter of 4 kilometers with an altitude of 273 meters. Concussion never make the eruption and tsunami simulation with the scenario of the collapse of the body of the mountain to see the potential of the tsunami based on the diameter and height of the mountain at that time.

Through simulation, within 45 minutes most of the wave has reached the coast in the vicinity of the Sunda Strait and into the Java Sea. Highest waves about 9 feet hit Ujung Kulon. While along the Anyer, Carita, and Labuan, the wave height of 4 meters to 7 meters. The first wave to reach those locations within 28-60 minutes. On the coast of Sumatra, the wave height of 1.5 meters to 4 meters and the first wave to reach the coast within 18-66 minutes.

In the simulation it is shown how the wave height and latency, especially in western Java, and potentially devastating casualties. Mitigation of tsunamis for the people on the coast around the Strait of Sunda become imperative. Moreover, these areas are now dense settlements and economic activities of citizens.

According Concussion, in its history, Mount Krakatau likely cause a tsunami has been several times when erupted. Note pujanngga Java, Rongowarsito, also mentioned, about the year 416, ancient Krakatoa erupted violently and sending tsunami until far into the interior of the island of Java and Lampung.