Following the sudden explosion on December 3rd (see below), which claimed 23 lives at the summit of the volcano, a modest explosive activity continued in the summit crater of the volcano. This resulted in ash emissions a few hundred meters high quite frequently, but they had very little impact on the population living near the volcano.
However, they replenished the summit area with materials that could be mobilized by rain, putting at risk urbanized areas near the gullies that descend from the volcano in mudflows, known as lahars in volcanic environments. They are particularly insidious as they only depend on rain and can occur long after an eruption. Furthermore, these mudflows can extend for several tens of kilometers and have a great erosive power…
A New Disaster, Five Months After the Previous One on this Volcano
On Saturday evening, around 10:30 PM local time, heavy rains occurred in the area, triggering lahars on the slopes of the volcano. The toll is still provisional, but at least 41 victims have been reported, while 17 people are still missing. Dozens of houses have also been destroyed or severely damaged, along with about ten bridges, roads, and at least twenty hectares of rice fields covered in mud…
A lahar, right in the middle of a village.
The toll, sad and impressive!
Significant damage!
Here, a road partially washed away in the river!
A Sudden Eruption of Mount Marapi Claims Several Lives
A strong explosion occurred on this very active volcano in Indonesia in the afternoon of December 3rd, while about sixty people were in the summit area. After a night of search, the provisional toll is quite heavy, with at least 11 fatalities, a few injured, and still twelve missing persons. No specific precursor signal was recorded before this event…
Article by Ludovic Leduc, published on December 4, 2023
Update as of December 7, 2023: the search operations have concluded, with an official toll of 23 dead and 52 survivors.
At 2:54 PM local time on Sunday, December 3rd, an explosion occurred on Marapi, a very active volcano on the Indonesian island of Sumatra. It formed an ash plume at least three kilometers high, as well as a pyroclastic flow that spread over three kilometers.On a mountain trail in Indonesia, an unexpected event occurred. An impressive explosion took place, with ash plumes seen from below and a pyroclastic flow at its base. Around sixty people were at the top of the volcano when it happened. Unfortunately, the toll is tragic, with eleven confirmed deaths and several injuries, including fractures and burns. The exact number of casualties is yet to be determined as twelve people remain missing.
The monitoring agency responsible for the volcano confirmed that there were no precursory signs of the eruption in terms of seismic activity, deformation, or visual observations. This event seems to be a non-magmatic explosion related to the hydrothermal system of the volcano. The hydrothermal system, located between the magma reservoir and the surface, consists of a mixture of magmatic gases and rainwater that infiltrates and heats up inside the volcano. Normally, these gases are released at the surface, forming continuous degassing. However, the heat and acidity of these fluids can alter the rocks, potentially blocking the degassing zones. This leads to an increase in pressure within the hydrothermal system, which can result in explosions. If the pressure rise is associated with deep-seated magma, the explosions are called phreatic, and if it’s related to hydrothermal activity, they are termed hydrothermal explosions.
These hydrothermal explosions can be silent or challenging to detect compared to magmatic eruptions. Such events have led to disasters like the one at Mount Ontake in Japan in 2014. Similar explosions have occurred in the past at Mount Marapi, especially when it has been at alert level 2 since 2011. Due to this risk, there is a three-kilometer exclusion zone around the crater of the volcano as a safety measure.