Santiaguito volcano (Guatemala): strong explosion and pyroclastic flows

Another violent eruption occurred at the lava dome yesterday morning (21 Sep) at 8:30 local time. Accompanied by explosions, the Caliente dome suddenly produced a series of major pyroclastic flows triggered by collapse of accumulated viscous lava at the southeastern rim rim and flank of the dome. The flows descended on all sides of the lava dome.
The explosions, accompanied by shock waves that could be heard in 20 km radius, produced an ash plume that rose to about 4.5 km altitude or about 2 km height above the crater. Significant (but smaller compared) ash plume rose from the pyroclastic flows. Ash fall occurred in Quetzaltenango, Santa María de Jesús, Zuníl and other areas downwind.
There has been no recognized precursor to the eruption, illustrating that the activity of the lava dome is highly unpredictable and potentially extremely dangerous. A similar eruption occurred almost exactly one month ago.