INSIVUMEH reported that in the evening on 20 May a new lava flow at Fuego traveled 300 m down the Ceniza (SSW) drainage.
The crater was incandescent and gas emissions were constant; avalanches descended the flanks 1 km and reached vegetated areas.
Explosions produced shock waves and ash plumes that rose just over 1 km above the summit.
Lahars descended the Las Lajas ravine on the E flank 1650 on 21 May and the Ceniza drainage on the SW flank.
There were 5-12 explosions per hour recorded during 22-26 May, generating ash plumes as high as 1.1 km above the crater rim that generally drifted 10-15 km in multiple directions.
Shock waves rattled buildings within a 20-km radius, particularly in areas on the S flank.
Incandescent material was ejected 100-300 m high and caused avalanches of blocks in the Ceniza, Seca (W), Trinidad (S), Las Lajas, and Honda drainages.
Ashfall was reported in several areas downwind including Santa Sofía (12 km SW), Morelia (9 km SW), Panimaché I and II (8 km SW), Ciudad Vieja (13.5 km NE), San Miguel Dueñas (10 km NE), and Antigua Guatemala (18 km NE).
Lava flows in the Ceniza drainage varied in length between 150 and 400 m long.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)