Located in Cameroon’s Northwest Region, Lake Nyos is one of the most dangerous places in the world. On August 21, 1986, a terrible natural event occurred in Lake Nyos. Known as the Lake Nyos disaster, this event came as a shock worldwide and required further measures to be taken to prevent similar events. The Lake Nyos disaster killed more than 1,700 people and 3,500 animals.
Lake Nyos is a crater lake located in Cameroon’s Northwest Region. It is located approximately 315 km northwest of the capital, Yaounde. Nyos is located in the Oku volcanic plain along the line of volcanic activity in Cameroon. It is located at a high depth on the flank of an inactive volcano. This lake is known as a volcanic reservoir because it is located in an area surrounded by volcanic formations and these formations hold the waters of the lake.
The Danger of Lake Nyos
Below Lake Nyos is a pocket of magma, and carbon dioxide (CO2) seeps into the water, turning it into carbonic acid. As such, Nyos is one of three lakes known to be saturated with carbon dioxide and is prone to limnic eruptions. Others are Monoun Lake in Cameroon, Democratic Republic of Congo and Lake Kivu in Rwanda.
In 1986, Lake Nyos suddenly released a massive CO2 cloud, causing the drowning of 1,746 people and 3,500 animals in nearby towns and villages. This event is the first known large-scale drowning event caused by a natural disaster. Although unprecedented, to prevent a repeat of this phenomenon, a degassing tube was installed in 2001 to siphon up from the lower layers of water to allow carbon dioxide to leak out in safe amounts. In 2011, measures were increased by adding two more tubes.
Today, the lake still poses a threat due to the weakening of its natural wall. A geological tremor could cause the natural embankment to collapse and water to flow into villages in the river below and even into Nigeria, escaping large amounts of carbon dioxide. For this reason, the immediate surroundings of the lake are constantly monitored and necessary security measures are taken.
What Happened in the Lake Nyos Disaster
Although a sudden CO2 outflow occurred in Monoun Lake in 1984, a similar threat was not expected in Lake Nyos. However, on August 21, 1986, an unexpected limnic eruption occurred in Lake Nyos, which caused a sudden release of approximately 100,000-300,000 tons of CO2 (according to some sources, this amount can be up to 1.6 million tons).
This gas cloud rose at about 100 kilometers per hour and stretched from Cha to Subum along an east-west oriented valley from the northern edge of the lake. This gas cloud then swept along at great speed, flowing through two valleys that diverged to the north. As a result of this disaster, a total of 1,746 people and 3,500 animals drowned in several rural villages about 25 kilometers from the lake, especially the villages of Cha, Nyos and Subum.
The villages most affected by this limnic eruption were Cha, Nyos and Subum. The explosion occurred suddenly and the gas cloud spread rapidly and affected these villages. This event showed that Lake Nyos could become unexpectedly dangerous and that other volcanic lakes with carbon dioxide accumulation could also contain potential threats. Therefore, it is of great importance to constantly monitor such lakes and to take the necessary safety measures.
Scientific Studies at Lake Nyos
The scientists came to various conclusions based on the evidence that a 100-meter spurt of water and foam had formed on the surface of the lake. A large amount of water that rose suddenly caused intense turbulence in the water and a wave of at least 25 meters hit the shore.
It is still not known exactly what triggers the catastrophic gassing. While most geologists think it was a landslide, some believe a minor volcanic eruption may have occurred on the lake bed. A third possibility is that cold rainwater falling into the lake triggered the overturning. Others still believe it was a minor earthquake, but this hypothesis seems highly unlikely as no shaking was felt on the morning of the disaster. Whatever the cause, the event caused the deep water to quickly mix with the upper layers and the CO2 stored under low pressure to bubble out of the solution.
About 1.2 cubic kilometers of gas is thought to be released. After the outgassing, the normally blue waters of the lake turned dark red as a result of the iron-rich water coming from the depths rising to the surface and oxidizing under the influence of the air. The level of the lake dropped by about 1 meter and the trees by the lake were toppled.
The 1986 disaster sparked a lot of research on how to prevent its recurrence. Although it is estimated that gas vents may occur every 10-30 years, more recent research shows that the lake’s water is released due to erosion. This erosion can reduce the carbon dioxide pressure in the lake’s water and lead to an earlier gas escape.
Precautions Taken at Lake Nyos
Several researchers suggested installing degassing columns to prevent outgassing in the lake. These columns remove the water, which was initially heavily saturated with CO2, from the bottom of the lake using a pump and release the gas by pressure loss. At Lake Monoun in 1992 and Lake Nyos in 1995, a French team led by Michel Halbwachs demonstrated that this approach is feasible. In 2001, the US Office of Foreign Disaster Relief provided funding for a permanent installation for Lake Nyos.
In 2011, Michel Halbwachs and his Franco-Cameroonian team laid two additional pipes for the complete degassing of Lake Nyos. This step is an important step towards making the lake safe.
Following the disaster, scientists surveyed other African lakes to see if a similar event had occurred elsewhere. Lake Kivu, which is 2,000 times larger than Lake Nyos, also turned out to be oversaturated, and geologists have found evidence of outgassing events around the lake every millennium.
The eruption of nearby Mount Nyiragongo in 2002 raised concerns that the gas eruption could be triggered as the lava flow pushed its way into the lake. However, as the lava flow stopped before reaching the lower layers of the lake, the gas was kept in solution under water pressure.
In 2005, a geologist named Isaac Njilah at Yaoundé University suggested that the natural volcanic rock dam found in the lake’s waters could collapse in the near future. Erosion showed that the dam was eroded, holes and pockets formed in its upper layer, and water had already flowed through the lower part. In addition, landslides outside also reduced the durability of the dam. Seismic activity from the lake’s volcanic base could cause the lake wall to collapse and approximately 50 million m3 (1.8 billion ft3) of water to flow into Northwest State and Nigeria’s Taraba state.
While acknowledging the weakening wall, the Cameroonian government, speaking through Gregory Tanyi-Leke of the Mining and Geological Survey Institute, argues it poses no immediate threat. Olaf Van Duin and Nisa Nurmohamed, who led the United Nations team, from the Dutch Ministry of Transport and Public Works, inspected the dam for three days in September 2005 and confirmed that the natural lip was weakened. Van Duin expected the dam to collapse in the next 10 to 20 years.
One potential way to prevent such a disaster is to strengthen the lake wall, but it should be noted that this process is quite time and costly. Engineers can also dig a channel to drain excess water; If the water level is lowered by approximately 20 m (66 ft), the pressure on the wall will decrease significantly.
For Article About The 10 Most Dangerous Lakes In The World CLICK HERE
