Continuous gas-monitoring site in Moku‘āweoweo Caldera, Mauna Loa

As magma rises toward Earth's surface, gases dissolved in the molten rock bubble out and escape through surface vents called fumaroles. HVO established sensors atop Mauna Loa in late 2005 to continuously monitor the concentration of carbon dioxide and sulfur dioxide gases and fumarole temperature within Moku‘āweoweo, the summit caldera. These sensors have recorded data for nearly 10 years, with some ups and downs in temperatures, but no measured change in the gases.