Modern Eruption Response

Volcanologists now watch active volcanoes closely. Tiltmeters detect ground swelling as magma rises, satellites track heat, and gas sensors monitor sulfur dioxide.

The great success was Pinatubo in 1991. Scientists read the warning signs weeks ahead and convinced the Philippine government to evacuate about 60,000 people from the danger zone. The eruption-day toll was near 300, and although later roof collapses under wet ash and camp deaths pushed the total to roughly 847, the timely evacuation had spared tens of thousands.

The 1985 Nevado del Ruiz disaster was the opposite. Scientists warned officials, but no evacuation was ordered, and a lahar buried Armero, killing about 23,000. The difference often comes down to whether authorities act on the warnings.