Explosive eruption at Santa Maria volcano, Guatemala
An explosive eruption occurred at Santa María volcano, Guatemala, at around 06:40 UTC on August 29, 2025, producing an ash plume that reached 4.2 km (14 000 feet) above sea level — approximately 500 m (1 640 feet) above the summit.
An explosive eruption occurred at Santa María volcano in Guatemala at approximately 06:40 UTC on August 29. According to the Washington VAAC, volcanic ash was observed at 4.2 km (14 000 feet) above sea level, about 500 m (1 640 feet) above the summit, at 12:30 UTC.
The eruption originated from the Santiaguito lava-dome complex, part of the Santa María volcanic system. This event follows weeks of elevated eruptive activity reported by the National Institute for Seismology, Volcanology, Meteorology, and Hydrology (INSIVUMEH).
During the week of August 12–19, high levels of activity were recorded at the Caliente dome, including lava extrusion, frequent explosions, and multiple pyroclastic flows.
Explosions occurred at a rate of 1–2 per hour, producing gas-and-ash plumes that rose 800–900 m (2 600–2 950 feet) above the dome and drifted west and southwest. Blocky lava effusion and collapses of older deposits triggered avalanches and short pyroclastic flows along the SW and S flanks.
Heavy rainfall on August 12 generated lahars in the Tambor drainage to the south-southwest. These hot, sulfurous flows carried debris including blocks up to 1 m (3.3 feet) in diameter, mixed with sediments and vegetation.
A larger eruptive event occurred on August 16, when accumulated material at the western crater rim collapsed around 16:30 LT, generating pyroclastic flows that traveled up to 4 km (2.5 miles) down the San Isidro drainage.
Ash plumes from the collapse reached 1 km / 3 280 feet above the summit and drifted 30–60 km / 18–37 miles west and southwest. Ashfall was reported in nearby communities including San Marcos Palajunoj (8 km / 5 miles SW), Loma Linda (7 km / 4 miles W), San Martín Sacatepéquez (11 km / 7 miles NW), and Colomba (18 km / 11 miles WSW), with minor ashfall in more distant areas such as La Reforma (28 km / 17 miles WNW), El Quetzal (26 km / 16 miles WNW), Coatepeque (31 km / 19 miles W), and Pajapita (50 km / 31 miles W).
In the evening hours of August 16, additional lahars descended through the Zanjón Seco and Tambor River channels.
Featured image: Santa Maria volcano eruption August 29, 2025. Credit: afarTV
Teo Blašković founded The Watchers in 2011 and edited it until 2026, covering seismic and volcanic activity, extreme weather, space weather and near-Earth objects. Articles on this page are his archive.
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