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.
A tachometer is an instrument designed to measure the rotation speed of an object, such as a gauge in an automobile that measures the revolutions per minute (RPMs) of the engine's crankshaft. This device traditionally is laid out with a dial, a needle that indicates the current reading and markings that indicate safe and dangerous levels.