Measuring Volcanic Collapse

Standing at the former time lapse camera site on the rim of Pool 1 of the perched channel, geologists measure the depth of the March 2009 collapse. A hammer head was attached to a steel cable and lowered over the edge until it hit the floor of the collapse pit. When the hammer hit the bottom, the cable was marked, and the depth was measured at 16.5 m (54 ft) deep.