A mud volcano has been erupting for ten years – and scientists are still clueless of what may have triggered it
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Sci & Tech
Mud volcanoes are widespread on Earth, with thousands of examples known worldwide. They are found in different shapes and sizes. But they behave a little like their molten-rock counterparts, going through long periods of inactivity with periodic violent eruptions.
Similar to molten volcanoes mud volcanoes may be inactive for years or may display violent eruptions at times. However, mud volcanoes don’t discharge molten hot lava from the Earth’s mantle, yet they release a cold mixture of gas, water, and solids.
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| Now abandoned, part of Sidoarjo town is entombed in mud meters thick. sawerigading |
Some of the most spectacular examples of mud volcanoes are in Azerbaijan where they can range from a few meters across to the size of a small mountain. They are commonly found at tectonic plate boundaries, and also underwater at river deltas where sediment is buried rapidly, causing unusually high pressures to build up underground. The muddy mix is also pushed to the surface by the buoyant gas it contains. About 86% of the gas released from these structures is methane, with much less carbon dioxide and nitrogen emitted. Usually, mud volcanoes grow slowly, through layer upon layer of mud.
Lusi, the Mud Volcano in Java Islands
In the recent decades, one of the most puzzling Mud volcano events occurred in Sidoarjo (Java Island) in 2006 which is only one of its kind, with Lusi by far the fastest growing mud volcano we know of, having drowned surrounding villages in a foul-smelling, emulsion-like mud. Estimates say that the mud cover there is up to 40m thick and also have taken few lives and made 60,000 people homeless this far.
Even after a decade, scientists have no clue of what could possibly have caused this event! So far there have been debates on its causative factors as to whether it is earthquake or drilling for gas exploration that would have triggered this.
Drilling or earthquake debate
The journal Marine and Petroleum Geology has published a special issue that examined the ways this amazing phenomenon is developing. It included a paper by geoscientists Stephen Miller and Adriano Mazzini that exhumes the debate of what could have possibly triggered the eruption, offering strong support for the earthquake as the trigger and dismissing the idea the borehole was responsible.
Whereas the team arguing that drilling has had this implication have stated that the lack of protection of steel and cement casing in the lowest region of the well that was drilled have transferred the pressure. This pressure exerted by water was good enough to fracture the surrounding rock or pre-existing faults. So the mixing with underground mud from the Kalibeng Formation, which makes up part of Java’s geology, this pressurized water and mud rushed to the surface through a fault, forming the Lusi mud volcano just 200 meters from the drilling site.
The alternative explanation is that despite its proximity the drilling well was coincidental and that the 6.3 magnitude Yogyakarta earthquake on May 27, 260km away had sent vibrations into the Kalibeng Formation’s mud layer, causing it to liquefy and rise to the surface under pressure.
Though there has been enough research and reasoning from scientists, none of them had enough data that convinces everyone says, experts.
Arsha, The Lantern Team
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