Authorities in Indonesia are watching over the increased activity of the Anak Krakatau volcano, which on Saturday caused a tsunami that left 430 dead and 159 missing around the Sonda Strait.
The volcanology agency of the country (PVMBG) today increased the alert level from 2 to 3 on a scale of 4 for the volcano after the increase in activity that caused the cancellation of at least twenty flights due to the ash cloud and smoke.
The spokesman of the National Disaster Management Agency (BNPB), Sutopo Purwo Nugroho, asked residents of the area to "calm down" their Twitter account and recommended that they remain informed.
Authorities have said that "people and tourists are prohibited from doing any activity within a radius of five kilometers from the crater on top of Mount Anak Krakatau," located in the Sonda Strait, which separates the islands of Java and Sumatra.
The meteorological agency BMKG recommended to avoid activities between 500 meters and one kilometer from the coast in this arm of the sea before the possibility of another tsunami like last Saturday.
Sutopo indicated that the best tsunami warning in the area is an increase in volcanic or seismic activity.
The Anak Krakatau, which entered the current phase of activity last July, continues to record strombolian-type "uninterrupted" eruptions, with the discharge of lava and the emission of incandescent rocks and columns of smoke that cover several areas of the seabed with ash. of the strait, added the spokesman.
According to Sutopo, the volcano registered a small-scale eruption on December 22, but satellite images show that it caused the collapse of its southwestern slope, which, when it fell into the sea, caused the tsunami that hit the west coast of Java and the south. of Sumatra with the result of the aforementioned 430 dead and almost 22,000 displaced.
The column of smoke thrown by the Anak Krakatau in its last eruption and that moves towards the southwest determined that the responsible of the civil aviation of the country diverted all the air traffic, although they do not foresee that it affects any airport, including the one of Jakarta, located about 135 kilometers east of the volcano.
"All flights are redirected due to the red alert for ash from the Krakatau volcano," AirNav news agency reported in a statement.
Meanwhile, rescue teams are working against the clock but with little hope of finding any of the 159 people reported missing.
Other teams are responsible for distributing food and water to the victims in the most remote areas.
The tsunami also forced about 22,000 people to flee to evacuation centers, in large part because the authorities have ordered the complete evacuation of small islands from the Sonda Strait.
To these are added 1,818 residents of two villages in the northwest of the Regency of Banten, the part of Java affected by the tsunami, which have had to be evacuated due to the flooding that the same area suffers.
Sutopo attributed the avenue of water to the overflow of the Cikalumpang River, caused by the intense rains that fall in the area, and that make difficult the tasks of rescue and assistance of those affected by the tsunami.
The devastating tsunami, of waves between three and five meters, did not trigger any warning because Indonesia does not have systems to detect giant waves caused by submarine landslides like the one that caused the Anak Krakatau.
The system of buoys installed after the devastating tsunami of 2004 that caused 167,000 deaths in Indonesia and another 59,000 in eleven countries bathed by the Indian Ocean, does not work due to vandalism and lack of maintenance, although the country has other less sophisticated meters.
Anak Krakatau, which means "son of Krakatoa", was formed several years after the eruption of Krakatoa in 1883, which was so strong that it caused 30,000 deaths and affected the global climate.
Indonesia sits on the "Pacific Ring of Fire", an area of great seismic and volcanic activity that is shaken every year by some 7,000 tremors, most of them moderate.