Tsunami warning in Indonesia: what’s happening

A natural disaster is worrying the Indonesian government: between 16 and 17 April, in fact, the Ruang volcano has begun an explosive and worrying eruptive phase, which risks generating a series of disastrous chain effects, including one tsunami. From a purely scientific and more purely geological point of view, these phenomena are anything but a surprise: this volcano, in fact, is located in an archipelago that has over 120 active volcanoes.

Not only that: Ruang, specifically, is located along the so-called Belt of Fire, an area characterized by a very high presence of seismic zones, mostly lying on a series of tectonic plates. From a human point of view, however, the situation is serious because it puts the lives and safety of hundreds of people at stake and in question, who, despite being aware of the presence of the volcano, still found themselves forced to leave as quickly as possible.

What’s happening in Indonesia?

Despite the enormous preparation of the Indonesian government and the inhabitants of the islands, the overall picture remains dramatic. In the space of a few days, more than 5 dangerous eruptions were recorded. The moments of pause between one and the other have, unfortunately, been filled by highly viscous lava flows. It is precisely the viscosity of the lava that causes a much slower descent along the already steep side of the volcano and contributes to the rise of columns of smoke that reached up to 3 kilometers in height.

At the moment there are no victims, but given all these characteristics the country’s volcanological agency, the Center for Volcanology and Geological Disaster Mitigationraised the alert to the highest level, also reporting the significant tsunami risk.

Why the tsunami warning?

But why would the eruption of a volcano lead to a tsunami? Not everyone knows that these phenomena are actually closely connected, especially if the eruption affects a volcano on an island like Ruang. The tsunami can be triggered by various phenomena. For example, the movement of magma within the volcano can weaken it structure of his sideand if the flank suddenly collapses into the ocean it can generate a devastating rogue wave.

It can also happen because of falling debris: ash, rocks and lava, coming into contact with water, can not only raise its level but can also trigger gaseous processes which contribute to generating pressure waves capable of propagating through the water and transforming into a tsunami. It should be added, moreover, that in addition to these scientific and natural considerations, there are precedents worthy of note.

In fact, already in 1871 the collapse of a part of Ruang island into the sea had contributed to raising a series of anomalous waves up to 25 meters high, which, pouring into coastal settlements, caused enormous damage (the village of Bahhuas, for example, was destroyed) and several deaths . Not only that: in September of 2018 an underwater eruption caused the partial collapse of the Ruang volcano, triggering a tsunami that killed over 400 people.

Evacuation and no fly zone

Given the enormous level of danger, from the beginning of the eruptions until now the Indonesian government has evacuated not only all residents, but also all those who, being on the islands or in the nearest settlements, were considered at risk. They have now been taken to safety over 2,500 peoplebut to make sure that there is no risk to anyone, the estimated number of displaced people should rise to around 11,000.

Most of these people, specifically, live on the island of Tagulandang, which is very close to Ruang and which has a total of 20,000 inhabitants. Meanwhile, the Indonesian airport was also closed Manado and we are thinking of establishing a no fly zone in that area, because for the moment the spread of volcanic ash and the jet of pyroclasts could put any flight at serious risk.