5. Localized landslides, rock falls 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 and crater lake (e.g. Taal( 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 of solfataras (a volcanic crater emitting only sulfurous and other gases).​