Lahar, lava, and pyroclastic material flowing down the side of a volcano.
Gas/chemicals under water can turn the water into acid, (or make it more acidic)
An earthquake while the volcano is erupting.
Is Not Possible...
A full out blast from a composite volcano on only one blow.
Every building and structure falling apart right off.
When driving through lava, it would have melted it quicker and melted the wheels.
