Signs of an impending Volcanic Eruption

By: Linen Calope Jr.

Signs of an impending volcanic eruption

According to the Philippine Institute of Volcanology and Seismology (PHIVOLCS), the government agency tasked with monitoring earthquakes and volcanoes in the country, the following are commonly observed signs that a volcano is about to erupt. These may vary from one volcano to another. 1. Increase in the frequency of volcanic quakes with rumbling sounds; occurrence of volcanic tremors; 2. Increased steaming activity; change in color of steam emission from white to gray due to entrained ash; 3. Crater glow due to presence of magma at or near the crater; 4. Ground swells (or inflation), ground tilt and ground fissuring due to magma intrusion; 5. Localized landslides, rockfalls and landslides from the summit area which not attributable to heavy rains; 6. Noticeable increase in the extent of drying up of vegetation around the volcano’s upper slopes; 7. Increase in the temperature of hot springs, wells crater lake near the volcano; 8. Noticeable variation in the chemical content of springs, crater lakes within the vicinity of the volcano; 9. Drying up of springs/wells around the volcano; and, 10. Development of new thermal areas and/or reactivation of old ones; appearance