Using Distant Seismometers to Monitor and Analyze Volcanic Eruptions
(a) The three closest seismic stations (red inverted triangles) to the Tonga eruption are more than ~760 km (~472 mi) away. (b) The timeline of earthquakes (yellow circles) at the Tonga eruption site shows the increase of seismicity immediately after the M5.8 during the initial eruption, followed by decreasing seismicity after the first couple of weeks. (from Kintner et al., 2022) There are more than 1000 active volcanoes on the planet that are not locally monitored, and some of them are very near potentially impacted populations. One such location is the Tongan capital of Nukualofa, where the only warnings before
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