The Weekly Volcanic Activity Report: August 20–26, 2025
New activity/unrest was reported for 6 volcanoes from August 20 to 26, 2025. During the same period, ongoing activity was reported for 18 volcanoes.
Significant temperature increase detected at Kawah II crater lake, Mount Kelimutu, Indonesia
A significant increase in water temperature and sulfur gas emissions was detected at Kawah II of Mount Kelimutu, East Nusa Tenggara, Indonesia, on August 26, 2025. The volcano is a well-known tourist destination due to its three color-shifting crater lakes. The last recorded eruption at this volcano took place in 1968 (VEI 1).
Alert level raised as unrest increases at Shishaldin volcano, Alaska
The Alaska Volcano Observatory (AVO) raised the Volcano Alert Level for Shishaldin volcano, Alaska, to Advisory and the Aviation Color Code to Yellow at 11:48 AKDT (19:48 UTC) on August 25, 2025, following increased seismicity, gas emissions, and vapor activity.
Effusive vents and explosive activity persist at Mount Etna’s Southeast Crater, Italy
Strombolian activity and lava flows continue at Etna’s Southeast Crater, with new vents opening on the southern flank. On August 25, the Aviation Color Code was briefly raised to Red following intensified eruptive activity.
The Weekly Volcanic Activity Report: August 13–19, 2025
New activity/unrest was reported for 7 volcanoes from August 13 to 19, 2025. During the same period, ongoing activity was reported for 20 volcanoes.
Mount Spurr quiets after prolonged unrest, alert and aviation codes downgraded
The Alaska Volcano Observatory lowered the Volcano Alert Level for Mount Spurr to Normal and the Aviation Color Code to Green at 10:07 AKDT (18:07 UTC) on August 20, 2025, following a gradual decline in unrest and the absence of ground deformation since March 2025.
Caldera cliff collapses in Santorini’s Imerovigli, triggering slope instability concerns
A large landslide occurred in the village of Imerovigli on the island of Santorini, Greece, at 15:30 LT (12:30 UTC) on August 20, 2025, collapsing part of the volcanic caldera cliff and generating a dense dust cloud over the area.
Mount Ruapehu Crater Lake heating up, New Zealand
Mount Ruapehu Crater Lake is warming again, with temperatures rising to 16°C (61°F) by August 19, 2025. The Volcanic Alert Level remains at 1, indicating minor volcanic unrest.
Lava reaches lower southern slope of Etna, 2 km (1.2 miles) from Altamontana trail
New lava flow from Mount Etna’s summit is advancing along the southern flank, reaching an elevation of about 2 270 m (7 450 feet). The most advanced front is now located about 2 km (1.24 miles) from the Altamontana trail, a major access route used for monitoring and hiking, following effusion that began on August 9, 2025.
Lewotobi volcano eruption sends ash cloud to 9.8 km (32 000 feet), Indonesia
Lewotobi volcano in Indonesia erupted on August 17, 2025, emitting volcanic ash up to 9 800 m (32 000 feet) above sea level, according to the Darwin Volcanic Ash Advisory Center (VAAC).
