Which mechanism causes lahar formation on stratovolcano slopes after heavy rainfall?

💡 Explanation

When rainfall saturates volcanic ash deposits, the increased weight and reduced cohesion trigger debris flows (lahars) because the unstable slurry moves rapidly downslope. Therefore ash deposit destabilization results, rather than pyroclastic snowmelt, lava ice melt, or tectonic uplift causing slope alteration which are alternative volcanic hazards under different eruptive conditions.

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