Volcano Watch: What causes the collapse/explosion events at Kilauea’s summit?

Graphic created by BRIAN SHIRO A generalized graphic of how a collapse/explosion event sequence can occur. The upper graphic represents a cross-section of the crater filled with rock rubble and the lower graphic is an example of a typical number of earthquakes observed during a particular phase of the collapse/explosion cycle. Initially, the piston is supported by the magma reservoir. It is stable and there is very low seismicity. Second, as magma drains, stress on the faults increases and there is an earthquake swarm on the caldera ring faults. Third, the piston collapses down from its own weight. A large collapse earthquake occurs and a plume can result.

Photos by INGRID JOHANSON Aerial images of Halema‘uma‘u crater from May 27 and June 18. Note how the crater has enlarged during a three-week period, as shown in the June 18 photo. Also visible are cracks on the crater floor because of ongoing subsidence at the summit.

At the summit of Kilauea Volcano, Halema‘uma‘u has changed dramatically since early May.