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Lahars move rapidly down valleys like rivers of concrete. If you are on the floor of a valley that leads from a volcano and become aware of an oncoming lahar, seek high ground. Lahar is an Indonesian term that describes a hot or cold mixture of water and rock fragments that flows down the slopes of a volcano and typically enters a river valley.  Of the five Cascade volcanoes, Mt. Rainier is the most significant threat. Lahars from Mt. Rainier have buried the. Kent Valley, but there is no evidence a lahar has reached Seattle in the past 10,000 years. mudflows, lahars are slurries of water and at least 60% sediment by volume. Lahars look and behave much like flowing concrete. They can travel at speeds of a few tens of miles per hour along gently sloping distal valleys. Higher speeds of more than 60 miles per hour are possible on steep slopes near Mt. Rainier. Additional information about lahars. 1  Seasonal debris flows – small lahars. 2  Landslide-derived lahars at Mount Rainier. 3  Lahar hazards at Mount St. Helens. 4  Preparing for lahar hazards. 5  Monitoring for lahars in the U.S. Lahars move rapidly down valleys like rivers of concrete. 1  Lahars can occur with or without a volcanic eruption. 2  Lahars and excess sediment cause serious economic and environmental damage to river valleys and flood plains. 3  Seasonal debris flows commonly occur on glacier-clad volcanoes. Voluminous lahars commonly grow to more than 10 times their initial size as they move downslope. In steep areas lahar speeds can exceed 200 km/hr (120 mi/hr), but as they move farther away from a volcano and decelerates in lowland areas, they eventually begins to deposit some of the load and decrease in size. Lahars generally occur on or near stratovolcanoes, such as those of the Aleutian volcanic arc in Alaska and the Cascade Range in the Western U.S. A moving lahar looks like a roiling slurry of wet concrete, and as it rushes downstream, the size, speed, and amount of material carried can constantly change. Voluminous lahars commonly grow to more than 10 times their initial size as they move downslope. In steep areas, lahars can exceed speeds of 200 km/hr (120 mi/hr), but as they move farther away from a volcano and decelerate in lowland areas, they eventually begin to deposit some of the load and decrease in size. Lahars can occur with or without a volcanic eruption. lahars are possible, a lahar would likely be preceded by volcanic and seismic activity. Although there are multiple ways in which a lahar can be generated, most of the largest ones are a mix of eruptive material, unstable rock water from of a volcano.” Lahars contain high concentrations of rock debris and can travel tens of meters per second. Most, but not all, are preceded by volcanic and seismic activity. Of the five Cascade volcanoes, Mt. Rainier is the most significant threat. Lahars from Mt. Rainier have buried the Query: how fast can lahars move
Output:
Lahars move rapidly down valleys like rivers of concrete.