Hi Kate. What we see is only the surface. How much of the glacier is being undercut can't be seen with the naked eye.

I would suspect though that if the right conditions prevail there could be a slide about 1/4 to 1/2 mile wide.

Lahars form 1) from debris avalanches that contain water from snow and ice which, when released, mixes with loose debris to form a lahar, 2) from pyroclastic flows and surges which release water that mixes with debris, 3) from pyroclastic flows which dilute themselves with river water as they travel downslope, 4) from natural dam failure (i.e. a lava flow dam or crater lake), and 5) from rainfall on loose material such as ash. Lahars that contain 20 to 60 percent sediment are usually very turbulent. Lahars that contain greater than 80 percent sediment usually flow more smoothly (laminar flow). These smooth flowing lahars usually travel much faster than their turbulent counterparts and can float boulders, cars, buildings, and bridges.

Lahars usually travel down valleys. They have a wide range of velocities varying from 1 m/s to 40 m/s. The velocity of a lahar depends on the channel width, channel slope, volume of the flow, and grain size composition (Scott, 1989). Lahars can travel long distances. Some lahars have traveled hundreds of kilometers from their source (Scott, 1989). The deposits of a lahar that traveled 60 km from its source at Mount Rainier can be found near the city of Seattle, Washington. The lahar's origin at Mount Rainier helped make that volcano a decade volcano. Take Care…Don in creepy town