TOKYO, Aug. 14 (Xinhua) -- Japan's weather agency on Friday raised the volcanic alert level for Mt. Aso in Kumamoto Prefecture from Level 2 to Level 3, citing intensified volcanic tremors and a sharp increase in volcanic gas emissions.

The Japan Meteorological Agency (JMA) Fukuoka Regional Headquarters issued the Level 3 warning on Friday afternoon, restricting entry to the mountain.

According to the JMA, the amplitude of volcanic tremors at the mountain has been increasing since around 7:00 p.m. local time Wednesday. A field survey conducted Friday confirmed a rapid rise in volcanic gas emissions, indicating heightened volcanic activity.

The agency urged people within a radius of about 2 kilometers of the Nakadake No. 1 crater to be on alert for large volcanic blocks and pyroclastic flows associated with the eruption.

The JMA said it has found no clear evidence that the recent powerful Kumamoto earthquake has directly intensified volcanic activity at Mt. Aso, but it will continue to closely monitor the situation.

Mt. Aso's alert level had been raised from Level 1 to Level 2 in June this year due to elevated volcanic activity. Friday's upgrade to Level 3 marks the first such increase since February 2022.