Starting in September, Indonesia's Mount Sinabung began erupting yet again. In the days that followed, ash and smoke were shot into the air multiple times. As a result, nearby towns turned gray from repeated blows by the volcano. Photo: A man uses his mobile phone as Mount Sinabung continues to erupt, with hot smoke spewing from the volcano, in the Karo district on the north of Indonesia's Sumatra island on November 18, 2013. Officials said a week ago at more than 5,000 people had fled their homes since the volcano erupted early this month. (Photo by Sutanta Aditya/AFP Photo)

A robot is seen on Mount Etna, Italy on July 4, 2017. Mount Etna, in Sicily, is a test bed for the approximately three-foot high, four-wheeled machine ahead of a future mission to the moon. It is being conducted by the German Aerospace Centre, the agency which runs Germany's space programme. (Photo by Antonio Parrinello/Reuters)

A tiger jumps while being trained at the Tiger Temple in Kanchanaburi province, west of Bangkok, Thailand, February 25, 2016. Thailand's controversial Tiger Temple, dogged for years by talk that it supplies the black market and mistreats its animals, is fighting to keep the big cats after wildlife authorities rejected a bid to extend a zoo licence that expired in 2013. The Buddhist temple, home to more than 100 tigers, has been investigated for suspected links to wildlife trafficking and wildlife activists have accused it of illegal breeding of the animals. Thai wildlife authorities have sent ten of the temple's tigers to a wildlife sanctuary. But the temple, which bills itself as a wildlife sanctuary, has denied links to illegal trafficking, and wants to hold on to its tigers. (Photo by Chaiwat Subprasom/Reuters)

A local man looks at a church on top of the Katskhi Pillar, rock mass about 40 meters high, in the village of Katskhi, Georgia, November 27, 2015. The church, built in the ninth century, was later abandoned and it collapsed but was rebuilt in 2003, according to local media. (Photo by David Mdzinarishvili/Reuters)

Sikhs wield swords during their clash inside the complex of the holy Sikh shrine, the Golden Temple, in Amritsar June 6, 2014. Sikhs wielding swords clashed inside the compound of their religion's holiest shrine on Friday, the 30th anniversary of a controversial raid by security forces that flushed out separatist militants holed up in the temple. REUTERS/Munish Sharma

A farmer tends to his field as Mount Sinabung releases pyroclastic flows in Tiga Pancur, North Sumatra, Indonesia, Saturday, June 13, 2015. The volcano, which was put on it highest alert level last week, has sporadically erupted since 2010 after being dormant for 400 years. (AP Photo/Binsar Bakkara)

A round circle of smoke coming from the mouth of the Etna volcano is seen in the sky during an eruption on the southern Italian island of Sicily April 11, 2013. Mount Etna is Europe's tallest and most active volcano. (Photo by Antonio Parrinello/Reuters)

Kelimutu is a volcano, close to the small town of Moni about 50 km to the east of Ende, Indonesia in central Flores Island of Indonesia.