"Happy Earth Day! Now get out." That's essentially what the Calbuco volcano said to residents of southern Chile yesterday evening (April 23) after it started billowing huge columns of ash and lava into the air. Authorities already declared a red alert for the area, and evacuated more than 4,000 people within a 20km (12 mile) radius of the eruption.

What's interesting is that this was an eruption that was completely unexpected. Calbuco had not been the subject of any special seismic monitoring, and locals had not reported feeling any microquakes - tiny subsequent earthquakes which usually signal when a volcano is getting ready to blow its top - weeks or months prior to this explosion.

"For us it was a surprise," Alejandro Verges, regional emergency director of the Los Lagos region where the eruption took place, told the media during a hasty conference. (Scroll to read on...)

The director added that evacuation efforts were fast and efficient. However, a 21-year-old mountain climber who was likely on the Calbuco mountainside when it erupted is reported missing.

By the time dusk fell, Chilean TV was airing spectacular footage of ash, bright orange flames, and flaming rocks belching from the mouth of the volcano.

Things escalated when lightning started sparking in the billowing ash plumes, creating a jaw-dropping "dirty thunderstorm" scene. (Scroll to read on...)

[Credit: Erupción del Volcán Volcán]

Chileans quickly took to social media to share some of the stunning photos and videos they captured.

"You know it's bad when lightning is on fire," one Reddit-user even joked.

This phenomenon was first made famous in 2008, when volcanic lightning was photographed by Carlos Gutierrez during a spectacular eruption of Chile's Chaiten Volcano.

Studies (Science 2006) of the phenomenon have revealed that enormous electrical charges can be generated when rock fragments, ash, and even ice particles in a volcanic plume collide - just as ice particles collide in regular thunderstorms. When these static charges breach a certain threshold, you suddenly have a scene like something straight out of the Rapture. (Scroll to read on...)

Cenizas del volcán Calbuco llegan a distintos puntos de ArgentinaLas cenizas del volcán Calbuco comienzan a llegar...

Posted by C.I.M.A.T - CENTRO INFORMACIóN MONITOREO ALERTA TEMPRANA on Wednesday, April 22, 2015

Chileans are expecting heavy ash-fall for the remainder of the week, with officials even in neighboring Argentina asking that residents in the city of Bariloche - about 60 miles from Calbuco - to stay indoors, according to BBC News.

The 6,500-foot Calbuco last erupted in 1972 and is considered one of Chile's top three most potentially dangerous volcanoes. The country boasts 90 active volcanoes in all.

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