Expenses incurred to prevent or reduce a loss for which the marine insurer would have been liable. The expenses may not qualify as general average expenditure but they can substitute for expenses that do qualify. If the substitution shows a saving, the substituted expenses are allowed in general average.

It refers to a fire of volcanic origin but would embrace a fire in a coalfield or oil well. The risk, and earthquake, are excluded from the standard fire policy but are insurable in the UK as an additional (special) peril.
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The Fire caused beneath the surface of the earth.