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.
Tiltmeter: works like a carpenter's level, and measures vertical movement along a fault. Creep meter: Measures movement along a slip-strike fault, so it measures horizontal movement along a fault. Laser ranging device: detects changes in distance to a reflector. Basically, it's a device that bounces beams off a reflector to detect fault movements. GPS satellite system: Uses a network of Earth-orbiting satellites and measures tiny vertical/horizontal movements of markers set u on the opposite sides of a fault.