How do you measure the power of a mudslide?

Answer 1

In science the word power is used to indicate the rate at which work is done, but in common use it is taken to indicate the force that a system can impose. I am assuming that your question is in relation to the letter.

The power of a mudslide (or any other landslide) is a function of two key parameters - first the mass of the material moving (i.e. how big the landslide actually is) and second its velocity (i.e. how fast it is moving). It is logical to think that a large, fast mudslide will be more destructive than a small, slow one. So, in simplest terms the power is given by measuring the volume of material, how heavy that material is and how fast it is moving.

The destructiveness of a mudslide is controlled by two other key factors. First, the nature of the terrain that the slide is moving over. So, for example, if the mudslide is forced to follow a narrow channel the power can be concentrated in comparatively small areas. Because the velocity can be high and the material is dense, such systems can cause enormous damage (search for the images of the Sarno landslides in Italy if you want to see this in action). On the other hand, if the slide can spread out over a large area then the level of destruction is generally lower, albeit over a greater area.

Second, a key parameter is the ability for people and assets to get out of the way. For this reason energetic mudslides at night are exceptionally dangerous, even for people in houses. The darkness plus the likelihood of people being asleep means that escape is far more difficult than it is during the day, when people are more likely to hear the slide coming and can see where they are going. Nonetheless, substantial numbers of people are killed in day time landslides, especially in less developed, mountainous countries such as N. India, Nepal, the Philippines and Indonesia.

The survival rate from being buried by a mudslide is quite low as the weight of even a small volume of material can prevent the victim from being able to inflate their chest (i.e. to breathe). Thus, if a mudslide is coming then people in the path should try to avoid being buried by the mud itself. Survivers usually get out of the way by running out of the path (run perpedicular to the landslide track) or they find something to prevent the debris from crushing their chest, such as a space in a building.