INSIVUMEH reported that beginning at 1400 on 17 May a lahar descended the Seca (Santa Teresa) drainage on Fuego?s W flank.
The lahar was 25 m wide, 1 m deep, and carried trees and blocks 1.5 m in diameter.
During 19-21 May explosions occurred at a rate of 5-8 per hour, and generated ash plumes that rose almost 1 km and drifted 10-20 km S, SW, and W.
Some explosions were accompanied by rumbling audible more than 30 km away, and shock waves that vibrated structures in Morelia (9 km SW) and Panimaché (8 km SW).
Incandescent material was ejected 200-300 m above the crater rim, and generated avalanches of material within the Seca, Ceniza (SSW), and Las Lajas (SE) drainages that reached vegetated areas.
Ash fell in areas downwind including in Santa Sofía (12 km SW), Morelia, Panimaché I and II, and Finca Palo Verde.
A lava flow 700-800 m long was active in the Ceniza drainage.
Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)