Volcano Watch — Tilting towards lava: How tiltmeters monitor volcano activity
A tiltmeter is a sensitive instrument designed to detect very slight changes in deformation of the ground. They are installed around volcanoes to monitor changes in the Earth’s surface caused by magma moving underground. These movements often precede eruptions, as pressure from magma pushes against the surrounding rock, causing the surface to bulge or shift slightly. Imagine a carpenter’s level laid on the ground at Kīlauea, oriented radially away from Kaluapele (the summit caldera). As magma enters the magma reservoir beneath the caldera and the volcano inflates, the end of the carpenter’s level closest to the caldera is raised upwards