“BBBOOOMMM!” you hear an explosion off in the distance then a wall of steaming hot water screams toward a house down in the valley below. The house is torn apart, but no one was in it lucky for you. You left for a trip and you were just coming home.
Lahars are a deadly mixture of volcanic debris and water, and it comes down mountains rushing up to 40 m/s. the family above was luck but not everyone is. Lahar is an Indonesian word made for the description above. It is also referred as a volcanic mudflow or debris flows. These dangerous freaks of nature can reach speeds up to 40 meters a second and 60 meters deep. It can carry from pebbles to large boulders 10 meters wide. The most surprising part is that the temperature varies widely and can reach 100 degrees centigrade.
They are formed by: 1) rapidly melting snow and ice by pyroclastic flows. 2) Intense rainfall on loose volcanic rock. 3) Breakout of a dammed area by volcanic deposits. 4) Debris avalanches.
Lahars are considered one of the most dangerous parts of a volcanic eruption increasing in size and speed as it flows down the mountainsides. They are similar to pyroclastic flows but contain 30% more water. Lahars that contain 20 to 60 percent more water tend to be more turbulent. Some that contain 80 percent more water flow more smoothly. But also can also have the consistency of concrete.
May 18 1980 Mount Saint Helens created a monster lahar that covered 24 square miles it destroyed 27 bridges and over 200 homes. It stranded 31 ships in up stream harbors in the Columbia River. It also decreased the depth of the river from 11 meters to 4 meters. Washington was devastated!!!!
As you see that lahars are very deadly and can boil you with scalding temperatures or smash you with giant pieces of rock. So please if you live by a volcano MOVE because if the ash or the lava doesn’t kill you the lahars will come pretty close. CM5