In a lava lake, such as the one present from 2008-18 in Kilauea’s summit Halema‘uma‘u crater, we can sometimes visually observe these fluid motions as ripples or sloshing of the surface following disturbances from rockfalls or gas bursts.
We can also detect deeper magma motion by using seismometers to measure ground vibrations. The seismic signals generated by magma motion, such as the example shown in the figure, are often distinct from other types of seismic signals. Compared to normal earthquakes, magma motion usually produces relatively slow vibrations, where the ground rises and falls over several seconds or tens of seconds.
For decades scientists have been interpreting these seismic signals at volcanoes in Hawaii and around the world as evidence of underground magma migration or accumulation, which can be used to look for signs that might indicate an impending eruption. in recent years, scientists have been learning new methods to use these seismic signals to resolve properties of underground magma systems that might not otherwise be measurable.
Magma or lava bodies vibrate most strongly at certain frequencies, called resonant frequencies, that depend on the body’s geometry and the properties of the magma or lava it contains, such as temperature and gas content. This is similar to how the musical notes produced by an instrument like a pan flute, bell, or a kāʻekeʻeke depend on the instruament’s shape and the properties of the air in it.
If a magma or lava is very fluid, for example like water rather than maple syrup, then a single perturbation can cause the magma body to resonate (vibrate or slosh at its strongest frequencies) for tens of minutes, such as the example shown in the figure.
Changes in the resonance frequencies can indicate changes in the amount of gas contained within the magma or lava, which is important for understanding its eruptive potential. Additionally, changes in the resonance duration (how long vibrations last) can indicate changes in the magma or lava temperature, which tells us if fresh hot magma is being brought up from deeper in the earth.
Such resonance has helped to reveal Kilauea’s shallow summit magma system geometry, for example suggesting that the conduit connecting its shallow summit magma reservoir with the overlying lava lake in Halema‘uma‘u from 2008-18 was more than 50 feet wide. it has also revealed complex magma dynamics over the past decade, including convective overturns and melt supply pulses, which inform the restless nature of Kilauea Volcano.
if you have a chance to stand near one of Hawaii’s active volcanoes, remember that the magma several kilometers beneath your feet could be subtly vibrating. And if visiting a volcano isn’t convenient, just tap on the side of a glass of water and watch the fluid resonance that results.
Volcano Activity Updates
Kilauea volcano is erupting. its USGS Volcano Alert level is at WATCH. Kilauea updates are issued daily.
Over the past week, lava has continued to intermittently erupt from the western vent within Halema‘uma‘u crater. All lava is confined within Halema‘uma‘u crater in Hawaii Volcanoes National Park. Sulfur dioxide emission rates remain elevated and were last measured at approximately 2,200 tons per day on March 8, during eruptive activity. Seismicity is elevated but stable, with few earthquakes and ongoing volcanic tremor. Summit tiltmeters show several deflation and inflation patterns over the past week.
Mauna Loa is not erupting and remains at Volcano Alert Level ADViSORY. Mauna Loa updates are issued weekly.
This past week, about 55 small-magnitude earthquakes were recorded below the summit and upper elevation flanks of Mauna Loa — the majority of these occurred at shallow depths less than 6 miles below sea level. GPS measurements show low rates of ground deformation over the past week.
Five earthquakes were reported felt in the Hawaiian islands during the past week: a magnitude-3.6 earthquake about 6 miles east-northeast of Pahala on March 8 at 6:49 a.m., a magnitude-3.2 earthquake about 6 miles east-northeast of Pahala on March 7 at 9:21 a.m., a magnitude-3.3 earthquake about 2 miles south of Pahala on March 6 at 10:07 p.m., a magnitude-3.3 earthquake about 2 miles west-southwest of Pahala on March 6 at 8:28 p.m., and a magnitude-2.5 earthquake less than a mile north of Kahaluu-Keauhou on March 5 at 8:51 p.m.
Visit https://www.usgs.gov/observatories/hawaiian-volcano-observatory for past Volcano Watch articles, updates, photos, maps, recent earthquake info, and more. Email questions to askHVO@usgs.gov. Volcano Watch is a weekly article and activity update written by USGS Hawaiian Volcano Observatory scientists and affiliates.