Kīlauea and other active Hawaiian volcanoes are ideal natural laboratories for researching how volcanoes work, because they are easy to access and have frequent eruptions and earthquakes. For more than 100 years, Hawaiian Volcano Observatory (HVO) scientists have developed new volcano-monitoring instruments and networks to record and document activity at Hawaiian volcanoes. Scientists use this monitoring data to better understand eruptions and earthquakes and to issue notifications of hazardous activity, which helps reduce impacts on communities. HVO also hosts scientists from around the world to help develop new monitoring methods and improve understanding of the dangerous consequences of earthquakes, tsunamis, and eruptions.
HVO's monitoring networks consist of more than 100 field stations with instruments that record and measure earthquakes, ground movement, volcanic gases, sound waves, lava advancement, magma volume below ground, and visual changes in eruptive activity. These field stations continuously transmit data by radio signal to the observatory, where it is recorded, processed by specialized computer programs, and analyzed by scientists.
In addition to ground-based sensors, satellite data are used to detect changes in ground elevation and surface temperature, which can indicate lava or other eruptive activity. Sudden shifts in data are detected automatically, and HVO scientists are notified immediately for closer inspection and response. If monitoring data indicate significant changes in a volcano's activity, scientists issue public notifications.
HVO, unique among U.S. volcano observatories, has the USGS responsibility to record and report on the thousands of earthquakes that occur every year in Hawaii, mostly beneath the Island of Hawai‘i. The HVO seismic-monitoring network is part of the USGS Advanced National Seismic System (ANSS).
Most earthquakes in Hawaii are directly related to the movement, storage, and eruption of magma at the active volcanoes. These volcanic earthquakes are usually small—typically less than magnitude 4—and pose only a limited hazard. Much larger earthquakes can occur in structurally weak areas within and at the base of Hawaiian volcanoes. These large events, such as the 1975 Kalapana (magnitude 7.7) and 2006 Kīholo Bay (magnitude 6.7), are widely felt and have the potential to cause extensive damage throughout the Hawaiian Islands.
Today, lava flows are the dominant style of activity of Hawaiian volcanoes, and tracking their advancement is a core HVO monitoring responsibility. Geologists document the movement and evolution of active flows under different conditions to better understand how lava advances and to provide warnings for people downslope from erupting vents.
Lava flows from the ongoing Pu‘u ‘Ō‘ō eruption on Kīlauea Volcano's East Rift Zone are monitored closely to determine their ever-changing eruption rates, locations, inundation areas, advance rates, and emplacement styles. Scientists also study the formation and evolution of lava tubes, which insulate the molten lava within them, allowing flows to travel greater distances.
Key methods for monitoring active lava flows include ground-based and aerial observations and mapping, webcam imagery, satellite-based data and images, and collecting lava samples for temperature, chemical, and mineral analyses.
The first volcanic gas measurements in the world were carried out at Kīlauea Volcano more than 100 years ago, and HVO's record of gas monitoring and innovation continues today. Measuring the composition of different volcanic gases and their changing emission rates is essential for characterizing the state of active volcanoes in Hawaii, because different gases are released as magma accumulates and rises beneath the surface. HVO began regular measurements of sulfur dioxide gas emissions at Kīlauea in 1979, and new methods for measuring these emissions are tested and used by HVO and other scientists in Hawaii. This gas monitoring is key to assessing volcanic air pollution (known locally as vog), which affects widespread areas downwind.