Combined vacuums
By Hawaiian Volcano Observatory
2016 (approx.)
![Color photograph of combined vacuums](https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/s3fs-public/styles/full_width/public/media/images/IMG_0312.jpeg?itok=GQ6SwDAH)
Detailed Description
The HVO dual vacuum set up used to extract wet sand from flooded tiltmeter casings. USGS photo.
Sources/Usage
Public Domain.