Nevadodel Ruiz
Nevadodel Ruiz, also called Mount Ruiz, is a volcano in Colombia. It is about 80 miles
(129 km) west of Bogotá, close to the town of Armero. It is the highest active volcano in
Colombia.There was a lahar after an eruption in 1985. About 23,000 people died when
the lahar covered the Armero, making this the most deadly lahar in the history of the
world. People who live near the volcano call it "the Sleeping Lion", because it was
dormant or sleeping for nearly 150 years before the Armero lahar.
On November 13, 1985, at 9:08 pm, Nevadodel Ruiz erupted; ejecting dacitic tephra
more than 30 kilometers into the atmosphere. The amount of magma erupted from the
volcano was 3% of that from Mount St. Helens in 1980. The eruption reached Volcanic
Explosivity Index 3. The material ejected was described by scientists as "unusually rich in
sulfur dioxide".Pyroclastic flows melted ice and snow at the summit, forming 4 thick
lahars that rushed down several river valleys. As most lahars do, the mudflows began as
flows of water, sand, and gravel, and mixed with clay along the way. The lahars were
up to 50 meters thick and six feet deep and traveled more than 100 kilometers. The
lahars destroyed many houses and towns. The town of Armero was completely covered
by debris, killing approximately 21,000 people (three-fourths of the population), as well
as affecting 13 other villages. The eruption caused an estimated 23,000 deaths, 5,000
injuries, and destroyed more than 5,000 homes. This was the second deadliest volcanic
disaster in the 20th century, ousted only by the 1902 eruption of Mount Pelee, and the
fourth deadliest eruption in recorded history. In addition, it was the deadliest lahar in
recorded history, and Colombia's worst natural disaster.