Volcano Watch: Magma chamber music can tell a revealing tale

USGS graphic The top plot shows a 2013 seismic recording of a normal shallow magnitude-2 earthquake that occurred a few miles south of the summit of Kilauea Volcano. The bottom plot shows a 2013 seismic recording of magma resonance after a large rock broke off the Halema‘uma‘u crater walls at the summit of Kilauea Volcano and then impacted the lava lake surface. Note the different timescales; the normal earthquake only lasted for about 20 seconds in total, whereas each magma oscillation cycle lasted for 40 seconds and the vibrations continued for over 20 minutes in total.

Disturbances to a magma or lava body — such as Kilauea Volcano’s underground summit magma reservoir or its current lava lake — can occur for a variety of reasons, including rising gas pockets or the fall of wall rocks into a lava lake. When a body of magma or lava is disturbed, the fluid in it can respond by vibrating or sloshing in a variety of ways.