Japan's weather agency maintained the highest alert level Monday after an explosive eruption the previous day at Sakurajima in Kagoshima Prefecture, southwestern Japan, although there were no reports of injuries.
The Japan Meteorological Agency said late Sunday that it was not currently expecting a large eruption similar to one at the same volcano in 1914 that caused many deaths.
The agency called on residents to be on high alert after a large rock flew around 2.5 kilometers from a crater, while warning pyroclastic flows could occur within a 2-km radius of two craters.
Evacuation orders were issued for 51 people in 33 households within a 3-km radius of the Minamidake and Showa craters, with 30 residents from 20 households sheltering at an evacuation center as of 10 a.m. Monday.
Following the previous day's explosive eruption at around 8:05 p.m., the agency raised the alert for the volcano from level 3 to 5 on its 5-point scale, warning people to evacuate. It was the first time that a level 5 alert was issued for the volcano.
It is just the second time the highest alert level has been applied to a volcano in Japan following a 2015 eruption on Kuchinoerabu Island in Kagoshima Prefecture.
The agency has observed minor crustal movements indicating expansion of the volcano since July 18, it said Sunday. There were four eruptions at the Minamidake crater from Saturday to Sunday afternoon, with plumes rising up to 1,200 meters.
During Sunday's explosive eruption, rocks were believed to have flown mainly in an east and southeast direction from the Minamidake crater.
A smaller eruption also occurred at about 6:30 a.m. Monday, with plumes rising 2,200 meters, the agency said.
While Japan's schools are currently on summer vacation, kindergartens, daycares and after-school children's clubs in the area have been canceled. Club activities provided at elementary and junior high schools are also suspended, with teachers being urged not to go to work.
The prefectural government and police are monitoring the situation from the air via helicopters.
Tense residents expressed fear late Sunday, with many surprised by the scale of the eruption. Mami Aoyama, who works at a hotel on Sakurajima, said she rushed to catch a ferry back to her home in an urban area of the prefectural capital of Kagoshima.
"The manager told me to 'just go home' so I quickly got on a boat home. I have no idea what happens tomorrow or after that," she said, calling it a "terrifying new experience."
One 76-year-old resident outside the evacuation zone said Monday she started packing clothes in a panic after learning of the eruption on TV. Normally she would hear the ground rumble, she said, but this time she "couldn't hear anything."
Yudai Yonekura, 35, spent a night at an evacuation center with relatives after seeing the windows at work shake from the eruption on Sunday night. "If we are forced to keep staying here, we'll need to think about getting a hotel," Yonekura said.
Sakurajima is one of the most active volcanoes in Japan. The large eruption in 1914 emitted enough lava to close the strait between the Sakurajima volcanic island in Kagoshima Bay and the Osumi Peninsula on Kyushu, the country's southwestern main island.