Answer:
1. Correlation spectrometer: instrument used to measure volcanic gases.
2. Plume: gassy smoke released by a volcano.
3. Tiltmeter: instrument used to measure ground swelling.
Step-by-step explanation:
A correlation spectrometer (COSPEC) is meant to measure the sulfur dioxide in a volcanic plume. It analyzes the solar ultraviolet light absorbed by sulfur dioxide to an inner standard. Reliable results are best-obtained.
Plume is a combination of volcanic scraps, fumes, and entrained air that are created in volcanic explosions.
A tiltmeter is an inclinometer intended to measure rather tiny variations from the vertical level, both on the ground or in constructions.