More than 100,000 people in the vicinity of the Mount Kelud in Indonesia were evacuated prior to a volcanic eruption that killed at least two people and covered nearby cities with sooty ash. 

REUTERS/Dwi Oblo 

The explosion shot ash and debris 12 miles into the air overnight and could be heard up to 125 miles away. Several cities including Surabaya, the second largest in the country with a population of 3 million, have been affected. Authorities raised a volcano alert to the highest level for 36 nearby villages around 90 minutes before the eruption, which was far from unexpected, according to the Associated Press

The 1,731-meter-high (5,680-foot-high) Mount Kelud in eastern Java — Indonesia's most densely populated island and home to more than half of the country's 240 million people — has been rumbling for several weeks and was under close observation. The mountain is about 600 kilometers (373 miles) east of Jakarta, the capital.

Witnesses to the scene describe a terrifying event. One farmer told the AP that "the eruption sounded like thousands of bombs exploding."

AP

People who have returned to their homes now must clear their properties of layers of ash, which in some regions are up to two inches deep. Initial reports said the two casualties of the eruption were killed when their house collapsed, unable to withstand the pressure of soot and debris, but an update concluded that two people died of smoke inhalation and a third may have been killed by a collapsed wall. 

The eruption also forced many of Indonesia's airports to shut down, and officials fear damage to plane engines. Yogyakarta airport's general manager Andi Wirson described the scene at the airport to the BBC, saying: 

The current conditions are that volcanic ash is now covering the runway, apron and tarmac. We have already measured the thickness of the volcanic ash, which is at 5cm on the runway and tarmac.

REUTERS/Dwi Oblo

Indonesia is home to about 130 active volcanoes, located near roughly 100,000 Indonesians. The country is prone to activity because it is on the "Ring of Fire," a series of Pacific fault lines, and residents are used to constant rumblings. Earlier this month, 14 people were killed in the unexpected eruption of Mount Sinabung on Indonesia's Sumatra Island.  

Smaller explosions could come from Mount Kelud in the coming days, and people are advised to keep away from the surrounding region for now.