Volcanic eruptions and Flow

  

I’ve  been reading articles on the volcanic eruption in Hawaii because I have land in the area.  Right now, it is not in any danger because most of the lava is escaping further south along various fissures.   At one point in the article, a scientist stated lava was moving at a speed of 17 mph.  This is a starting point for creating some real world problems involving a real world event.  Imagine, if this math could be combined with a unit taught by the science department!

There are 4 things which effect the speed of lava.
1. The composition of the lava and the amount of gas.  In other words it’s viscosity.

2. The amount of material coming out do the volcano.

3. The slope of the land.  The steeper the slope, the faster it will flow.



4. Whether it’s flowing in a sheet, a channel, or a tube

If lava is traveling fast, it moves about 17 mph while a more realistic speed is 6 mph.  Lava can get down to half a mile an hour if it’s quite viscous.  Now consider the average speeds of a human.  They can run at 20 mph, jog at 7 mph and walk at 3 mph.  This means it is possible to outrun any lava flow.  There are a few flows that get going extremely fast but I gave average speeds.

Now if students check out a topographic map to check out the slope of the area with current volcanic activity in Hawaii, they can get a better idea of slope, shape of the land the lava travels across to get a better feel for why the lava is going 17 mph.  I just down loaded an app which gets me access to topographic maps.

The teaching engineering site has two lovely lessons which contribute to a student,s understanding of how far lava flows and how to find the speed of flowing lava.   The first exercise has students learn about fluid flow in regard to volume, slope, viscosity, and surface through hands on experimentation while the second continues with how volume, viscosity, and slope effects the area covered by lava.  Both of these exercises require mathematical calculations.

In addition, one of the places in Australia offers a lesson on the speed of lava.  I think it is good to offer some lessons as activities or experiments sine it adds a real world element to the whole think.  Besides, someone will ask how they managed to calculate the speed of lava if it is so hot.

This provides the basis for a wonderful cross curricular activity among English, Math, Science, and Social Studies because they can look at so many facets of this one topic.

I will be back in the states by the weekend so I will be back to using my computer instead of using my iPad.  Let me know what you think.