Albay Province is highly susceptible to rainfall-induced landslides and volcanic mudflows (lahars) due to its steep terrain, loose volcanic materials, and frequent heavy rainfall from tropical cyclones, shear lines, and the southwest monsoon. PAGASA regularly issues weather advisories warning that moderate to heavy to intense rainfall can saturate slopes and trigger landslides and debris flows, particularly in mountainous and upland areas of the province. During periods of prolonged or intense rainfall, PHIVOLCS releases lahar advisories for Mayon Volcano, cautioning that volcanic ash and pyroclastic deposits on its slopes may be remobilized into fast-moving lahars that can flow along river channels and threaten downstream communities. Hazard maps and preparedness guidelines from PHIVOLCS, together with rainfall warnings from PAGASA, are used by local government units to identify high-risk areas and implement pre-emptive evacuations to reduce loss of life and damage to property.
WHAT IS A LANDSLIDE?
A landslide is the mass movement of rock, soil, and debris down a slope due to gravity. It occurs when the driving force is greater than the resisting force. It is a natural process that occurs in steep slopes. The movement may range from very slow to rapid. It can affect areas both near and far from the source.
Landslide materials may include:
- Soil
- Debris
- Rock
- Garbage
LANDSLIDE TRIGGERS
- Natural triggers
- Intense rainfall
- Weathering of rocks
- Ground vibrations created during earthquakes
- Volcanic activity
- Man-made triggers
Movement can occur in many ways. It can be a fall, topple, slide, spread, or flow.
