Examples of Historic Pyroclastic Flows

The world has many examples of historic pyroclastic flows. The oldest known flow is Mt. Vesuvius, Pompeii in Italy. Donna O’Meara in Volcano shows examples of each of these many volcanoes that have erupted over time. Four recent flows occurred in Montserrat in the Caribbean, Washington USA, Pinatubo in the Philippians, and Nevado Del Ruiz in Columbia.

Pyroclastic flows comprise lethally hot volcanic debris made of gas along with rocks and ash. They flow at high speeds making it difficult for anything to escape its path. These can cause tsunamis, earthquakes, rock slides and mudflows. Earthquakes often precede them. The flows can burn and suffocate whatever ends up in front of it.

Castle Peak, Soufriere Hills, Montserrat in 1997 erupted unexpectedly. The debris from the explosion coursed into the White River and out into the Caribbean Sea. Though five thousand people lived nearby, none lost their lives because they evacuated the area three weeks before the disaster. The flows began in January of that year. By February, the flows buried Castle Peak. The flows continued until the collapse of the volcano in 1998.

In 1991, the people in the Philippines on the island of Luzon experienced the effects of a volcanic debris flow from the Pinatubo volcano. This mudflow covered towns and villages and removed vegetation and everything in its path. In its wake, it left agricultural land and fishponds devastated and affected over a million lives producing 847 deaths and many injuries. Sixty-one towns became casualties of the volcano. Here, rain combined with the already fast-moving debris increased the amount of damage they sustained. It damaged many modern conveniences, and collapsed many homes and buildings.

Mount Saint Helens in Washington State erupted in 1980, sending hot debris down its sides and destroying much of the life around it. The flow moved quickly at around sixty miles an hour, reaching almost seven miles away. Seventeen different flows accompanied the eruption of the volcano. Fifty-seven people lost their lives on May 18, along with thousands of wild animals in the area.

The pyroclastic flow in the Andes of South America caused 25,000 deaths to human beings and 15,000 deaths to animals. Historically, Nevado Del Ruiz has deadly flows of mud. In 1985, the mountain played games with the citizens of Amero. The officials at first ordered an evacuation, but then the mountain stopped erupting. A couple hours later, the flow came and melted the ice cap of the mountain, pushing the debris down the mountain at breakneck speeds. Nearly 13,000 people lost their homes.