Jakarta, domclub Indonesia
—
Volcano
In Ethiopia, Hayli Gubbi, erupted on Monday (24/11), after 12 thousand years of ‘sleeping’ or experiencing a dormant period.The volcanic eruption ejected volcanic ash as high as 14 kilometers into the atmosphere.
So can a volcano that has been ‘sleeping’ for thousands of years suddenly erupt again?
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Head of the Center for Volcanology and Geological Disaster Mitigation (PVMBG) Hadi Wijaya explained that a volcano that appears to be sleeping does not mean it is dead.
“Dormant volcanoes remain connected to the magma system at depth, but there have been no eruptions for tens to hundreds of years so they are often considered sleeping,” said Hadi when contacted
domclubIndonesia.com
, Tuesday (25/11).
“Dormant volcanoes are not an indicator that magma has stopped rising to the surface,” he added.
He explained that there are several mechanisms that trigger magma to rise to the surface or erupt, including the formation of new magma at depth or magmatic recharge.The mechanism of rising fresh magma from the Earth’s mantle or lithosphere in this case causes an increase in pressure, accumulation of volcanic gas, and weakening of the cover rock.
“If the pressure exceeds the strength of the rock, an eruption will occur,” he said.
Apart from that, another mechanism is magma migration to the surface or magma intrusion.Hadi said a new dike or sill could break rocks, generate volcanic earthquakes, increase temperature and degassing.
This process, said Hadi, can occur after hundreds of years of dormancy.
Another factor that triggers eruptions is the interaction between water and a heat source or what is usually called hydrothermal pressurization.Hadi explained that this happens when the groundwater system is exposed to hot magma, causing high pressure steam to form, resulting in a sudden phreatic eruption.
Phreatic eruptions are eruptions that are dominated by water vapor, caused by water contact with heat beneath the volcanic crater.
Tectonic earthquakes can also cause dormant volcanoes to erupt.Pressure earthquakes of great strength can open new cracks, change pore pressure, and disrupt the stability of the magma system, ultimately causing an eruption.
Another trigger factor is changes in external pressure such as crater erosion, lava dome landslides, and changes in water load due to extreme rainfall.
“Phreatic eruptions most often appear suddenly, even on mountains that have been silent for a long time,” said Hadi.
Trigger for the eruption of Mount Hayli Gubbi
Hadi said that Mount Hayli Gubbi was classified as a dormant mountain which experienced a sudden eruption with a phreatic-phreatomagmatic character.
Mount Hayli Gubbi is south of Erta Ale which is an active rifting area in Afar, Ethiopia.This region is included in a dynamic tectonic zone where three plates are moving away from each other, namely the Nubian, Somali and Arabian plates.
“This process of continental expansion causes the crust to stretch, thin, and new cracks form, making it easier for magma to rise to the surface,” explained Hadi.
Therefore, the Afar region is known as one of the most active areas in the world regarding oceanic crust formation and continental separation.
“The revival of Mount Hayli Gubbi activity was most likely triggered by magma intrusion driven by the rifting process,” said Hadi.
“This assumption is reasonable because studies around Erta Ale show that magma intrusions can propagate far below the surface and affect other volcanic systems,” he added.
In other words, he said, even though the surface appears calm, the Afar rifting process creates a large accumulation of pressure under the crust that ultimately triggers a sudden eruption.
(lom/dmi)
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