Historical Examples

Examples of effects of ash on power facilities and transmission from eruptions during historical time:

The consequences of loss of electricity supply are widespread, and many other public utilities (e.g. water supply pumps, radio and telecommunication facilities) may be inoperative for the duration of the power loss unless local backup power supplies (batteries and generators) are available.

The following table shows the general effects of ashfall on power facilities and electrical distribution systems that resulted from several historical explosive eruptions in the world.

Effects of ashfall on electrical supplies

Volcano (Nation); Eruption year Effects
Mount St. Helens (USA); 1980 Insulator flashovers in areas receiving >5 mm (1/5 in) of ash, in conjunction with rain.
Redoubt Volcano (USA); 1989-90 Insulator flashovers in areas receiving ash, in conjunction with rain.
Rabaul (Papua New Guinea); 1994 Wire and cross arms damaged by collapsed buildings and tree breakage.
Ruapehu (New Zealand); 1995 Insulator flashovers on high voltage lines receiving moist ash.
Ruapehu (New Zealand); 1996 Flashover at substation due to water (from clean-up operations) settling on ash-covered insulators.
Copahue (Argentina); 2000 Heavy ashfall cut off power for several hours and eruption-related damage also cut off the power supply.

See Also:
Case Studies > Rabaul 1994
Case Studies > Ruapehu 1995-96