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.
The water-seal spirometer is a counterweighted bell inverted into a water reservoir; the bell rises and falls as the patient breathes. Its motion moves either a transducer or a pen that records volume data on calibrated chart paper mounted on a rotating drum (kymograph). The low-friction water seal and counterweight limit resistance and back pressure so that the measurement itself does not adversely affect the patientâs response. In the second type, a dry rolling seal is used instead of water between the bell and its surrounding cylinder. Rolling-seal spirometers are often mounted horizontally to eliminate the need for a counterweight and to minimize the effect of gravity. The âwaterlessâ or Stead-Wells dry-seal spirometer combines the water- and rolling-seal concepts.