Volcano Watch: How tiltmeters monitor volcano activity

This photo shows releveling maintenance being conducted on an analog tiltmeter located near Uekahuna bluff at the summit of Kilauea, within Hawaiʻi Volcanoes National Park. (M. Warren/USGS image)

Over the past century, technological advancements have vastly improved volcano monitoring. One key innovation was the introduction of modern borehole tiltmeters, devices that measure very small changes in the inclination of the volcano’s surface.