The Hawaiian Volcano Observatory celebrated the 30th anniversary of Mauna Loa's last eruption (in 1984) on March 25, 2014, underscoring that it has been a realtively quite 3 decades at the world's largest active volcano.
A tiltmeter, is a type of instrument used to detect any kind of tilt in the structure to which it is attached. Most tiltmeters use an air bubble in a liquid-filled tube, much like a typical carpenter's level, but are equipped with sensitive electronics that can detect even the tiniest change in tilt. They either sound an alarm or transmit the data to a remote monitor or other device.
Volcanologists also use a device called a spectrometer to measure how the gases being emitted by the volcano affect the light. Based on the light above a gas vent, they can tell if the volcano is emitting hydrogen sulfide or carbon and sulfur.he most basic tool used by any volcanologist is a simple rock hammer, used for breaking off samples of igneous rock for laboratory analysis. Other samples are collected from the volcano's core using a drill.