Mud Volcano in Indonesia - A Devastating Natural Disaster from Both Natural Force and Human Greed

Mud volcanoes form when a combination of mud, liquids, and gases erupts onto the Earth's surface.

Rice farmers living in Sidoarjo Regency, Indonesia, woke up to a strange sight on May 29, 2006. The ground where they lived had cracked open overnight and was spewing steam.

Over the following weeks, water, hot mud, and natural gas were added to the mixture and sprayed onto the ground. As the eruption grew more violent, mud began to flow across the fields. Alarmed residents evacuated, hoping for a quick end to the eruption.

But it didn't stop. As the weeks passed, the mud spread, engulfing entire villages. In a frantic race against time, the Indonesian government began building dikes to contain the mud and stop it from spreading. As the mud overflowed these dikes, they built new dikes behind the first set. The government eventually succeeded in stopping the mud's advance, but not before the floods had wiped out dozens of villages and forced 60,000 people to evacuate.

Why did the Earth suddenly 'vomit' such a huge amount of mud?

Mud, liquid, and gas are erupting on the Earth's surface.

Mud Volcano Overview

The Lusi Structure – shortened from Lumpur Sidoarjo – is an example of a geological feature known as a mud volcano . They form when a combination of mud, liquids and gases erupts onto the Earth's surface. The term 'volcano' is borrowed from the traditional concept of volcanoes, with layers of molten rock rising to the surface.

In most cases, mud is pushed to the surface fairly quietly. But sometimes, eruptions are quite violent. Furthermore, most of the gas released from mud volcanoes is methane, which is highly flammable. This gas can ignite, creating violent and spectacular eruptions.

Mud volcanoes are uncommon in Europe and North America, but are common in many other places, not only Indonesia but also Azerbaijan, Trinidad, Italy, and Japan.

They form when liquids and gases that have built up under pressure inside the Earth's core find their way to the surface, through a network of cracks . The liquids move up these cracks, carrying mud with them, creating mud volcanoes as they escape.

You can think of this as similar to a car tire that contains air. As long as the tire is intact, the air is safe inside. However, when the air has a way to escape, it will start to leak out. Sometimes the air leaks out as a slow leak, and other times we see a forceful blowout.

The effects of the mud volcano in Sidoarjo spread to 7 square kilometers.

When fluids flow underground in the Earth, they often cannot escape under the weight of overlying sediments. Some of these fluids are trapped in the sediment as it is deposited. Other fluids may migrate in from deeper sediments, while others may be created in situ by chemical reactions in the sediment. Some important types of chemical reactions produce oil and natural gas. And finally, fluids can become overpressurized if they are forced by tectonic forces during mountain building.

Overpressure is also a common occurrence in oil and gas drilling, but it is usually planned in advance. One major way to deal with this excess pressure is to fill the borehole with a dense drilling mud that has enough weight to suppress the excess pressure.

But if wells are drilled with insufficient mud, any fluid under excessive pressure can surge to the wellhead and spray to the surface. Famous examples include the 1901 Spindletop blowout in Texas and the 2010 Deepwater Horizon disaster in the Gulf of Mexico. In those cases, oil, not mud, gushed out of the well, causing an explosion.

Scientifically, mud volcanoes are considered to be windows that open up interesting information about everything deep inside the Earth . Mud volcanoes can bring up materials from depths of 10 km below the Earth's surface. Therefore, their chemical composition and temperature can provide useful insights into processes occurring deep inside the Earth, information that we cannot obtain in any other way.

For example, analysis of erupted mud from Lusi has revealed that the water was heated by an underground magma chamber associated with the nearby Arjuno-Welirang volcanic complex .

Lusi's mud is still erupting

Homes were submerged by mudflows, forcing the evacuation of 60,000 people.

Today, more than 16 years after the eruption began, the Lusi structure in Indonesia continues to erupt, but at a much slower pace. Its mud has covered a total area of ​​about 7 square kilometers, or more than 1,300 football fields, and is contained behind a series of dykes that have been built to a height of 30 meters. Nearly 180,000 cubic meters of mud have been erupting, and this is expected to continue for the next 30 years.

As interesting as the natural phenomenon is the legal battles over blame for the disaster. The initial blowout occurred 200 meters below the surface of a gas exploration well, leading to accusations that the oil company was responsible for the incident. The operator of the well, oil and gas exploration company Lapindo Brantas, countered that the blowout was natural, caused by an earthquake that had occurred days earlier.

Those who believe that the gas well caused the blowout argue that the well did cause a blowout due to insufficient mud weight to relieve the pressure, but that the blowout did not travel all the way to the surface. Instead, the fluid only traveled part of the way up the well before being pumped into one of the geological faults and erupting on the surface a few hundred meters away. Furthermore, they argue that the earthquake was too far from the well to have any effect.

A worker at Sidoarjo checks the water temperature near the Lusi mud volcano in 2011.

In contrast, earthquake proponents believe that the Lusi eruption was caused by an active hydrothermal system below the surface . They argue that such systems have a long history, affected by earthquakes far away, so the argument that Lusi was too far away from the earthquake is invalid.

Furthermore, they suggest that a pressure test of the well conducted after the eruption began showed that the well was intact, without any fractures or fluid leaks, and there was also no evidence that any drilling mud had escaped from subsequent eruptions.

In 2009, Indonesia's Supreme Court dismissed a lawsuit alleging negligence on the part of the company. That same year, police dropped criminal investigations into Lapindo Brantas and several of its employees, citing a lack of evidence. Although the lawsuits have been settled, the debate among researchers continues.