Mount Aso continued to erupt Thursday, diverting and canceling flights headed to and from the Kumamoto Airport, which is located to the west of the volcano, due to concerns about volcanic ash clogging up engines and low visibility.

The Japan Meteorological Agency issued a Level 2 warning for the volcano and urged residents to be always alert. Intense activity from Mount Aso started Nov 25, sending smoke and volcanic ash as high as half a mile in the air. Volcanic ash fell on the Oita and Miyazaki Prefectures located almost 30 miles away from Mount Aso, affecting the city of Bungo-Ono and the town of Gokase.

Aside from smoke and volcanic ash, rocks were also shooting out Wednesday around the No. 1 crater, which is located close to the nearly mile-high peak of the mountain. Thursday, more rocks were spewed out, shooting up to 1/10 of a mile in the air.

Volcanic warnings for Mount Aso have see-sawed between Level 1s and 2s since September 2013. A Level 1 warning meant the mountain is not exhibiting unusual activity while a Level 2 warning prohibits access to the crater. Back in August, a Level 2 warning was issued for the volcano.

There were slight deformations on the mountain's shape indicating the possibility that there was magma movement during the latest eruptions. However, it is believed that the eruptions will not intensify and worsen, with rocks shooting no more than a little over a mile from the crater. A Level 3 warning restricts entry to Mount Aso but it is unlikely to be issued, added agency officials.

This recent volcanic activity from Mount Aso comes just two months after central Nagano's Mount Ontake erupted without warning, killing over 60 hikers in the area. Last month, experts warned of an impending disaster on Kyushu Island which has seen seven massive volcanic eruptions in the last 120,000 years. Should the disaster unfold, the island can be buried under molten in just two hours.

An active volcano in the Kyushu center, Mount Aso features one of the largest calderas in the world with a diameter of up to 15.5 miles and a circumference of more than 62 miles. Active volcanic peaks are located at the center of the caldera, including Mount Nakadake. Poisonous gases are released by the volcano so even on days that Mount Aso is normal; people with respiratory issues are advised to avoid the crater.