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Communications are a vital part of everyday life and critical in any emergency. Radio, TV and telephone communications are extremely vulnerable to disruption during a volcanic ash fall and may fail completely in eruption-affected areas.

The disruptions to communications that may result from volcanic ash falls include interference to radio waves due to atmospheric conditions, overloading of telephone systems due to increased demand, and direct damage to communications facilities. Indirect impacts can also occur from disruption to electricity supplies or transportation of operations or maintenance workers. The loss of communications makes disaster management extremely difficult under and following eruption conditions.

Interference from ash

Large quantities of electrically-charged ash can be generated in an eruption column. This charged ash can cause interference to radio waves and render radio and telephone systems inoperative. However, there are examples of radio and telephone communications continuing to function around an erupting volcano and in areas receiving ash falls.

Overloading of systems

During most natural disasters telephone and radio communications are susceptible to overloading by public and emergency services use. Response organizations report frequent overloading of their telephone lines even in cases where the general system remains operative.

Damage caused by ash

Most modern telephone exchanges require air-cooling systems to keep electronic switching gear below critical temperatures. Exchanges with external air-cooling systems are thus vulnerable to over-heating if these units fail or are switched off (due to ash falls), even if the exchange itself is sealed. Some exchanges are sealed to keep out corrosive geothermal gases such as H2S. However, any ash entering telephone exchanges can cause abrasion, corrosion, or conductivity damage to electrical and mechanical systems.

Effects of ash fall on communication systems during recent explosive eruptions in the world.

Volcano; eruption year Overloaded telephone systems Interference in communications Damage to communications Inoperative communications
Mount Spurr; 1953 yes      
Mount St. Helens; 1980  yes      
Ruapehu; 1995  yes      
Katmai; 1912       yes
Surtsey; 1963   yes    
Mount Pinatubo; 1991   yes    
Pacya; 1995     yes  

Keeping ash out

The most serious problems to communications systems result from the conductive and abrasive properties of ash. Measures that can help prevent ash falls impacting greatly on communications systems include:

Removing ash

The following recommendations on the removal of ash from communication systems have been based on the experienced gained from the 1980 eruption Mount St. Helens, Washington:


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