Sat, 14 May 2022, 17:32
17:32 PM | BY: LEANDRA
Volcanic lightning at Colima Volcano (Volcán de Colima) (image: Hernando Alonso Rivera Cervantes, National Geographic)
Volcanic lightning is not only one of the most mysterious and impressive phenomena observed in some volcanic eruptions, but also important to science.
What creates volcanic lightning?
Volcanic lightning can be created in different scenarios during explosive volcanic eruptions, and are often called “dirty thunderstorms.” These “dirty thunderstorms” are a dramatic form of static electricity release.
In regular thunderstorms, lightning happens when ice is present inside clouds and becomes electrified during collisions in vertical updrafts. Without ice, there is no lightning.
In the case of volcanic lightning, however, lightning occurs when oppositely charged particles such as fragmented pieces of lava or ash grains collide with one another. Lightning happens more often closer to the vent.
Like in regular thunderstorms, ice can enhance the electrification of larger eruptions that produce large-scale plume lightning. Ice can be present in colder climates or in clouds interacting with a volcanic plume.
How is volcanic lightning detected?
Volcanic lightning events produce electromagnetic pulses which can be recorded via microphones, seismographs, low-frequency antennae, or infrasound devices.
Volcanic lightning can also be detected using high-speed cameras, infrared thermal imagery, electrical resistivity imaging, or satellite remote sensors.
Lightning events can also leave physical evidence in the geological record, such as in eruption deposits. Differing ash textures or melted silica can indicate when volcanic lightning has occurred and altered the deposits.
Why is volcanic lightning important?
Volcanic lightning, besides creating an electrifying spectacle during explosive eruptions, can also be incredibly helpful for volcanologists monitoring volcanoes.
When detected, the presence of this lightning can provide an indication that an eruption is occurring even when a volcano is not visible, such as at nighttime or during inclement weather.
Lightning may also provide insight into changing eruption conditions and associated hazards.
Factors such as ash grain size, grain size distribution, ash chemistry, and ash magnetism are tied to the presence and characteristics of volcanic lightning.
Volcanic lightning may even be used to map the structure and shape of an eruption plume or column. Increasing volcanic lightning strokes may indicate expansion of the volcanic plume, increasing eruption rates, and growing explosivity of the volcano.