Semeru volcano (East Java, Indonesia): spectacular pyroclastic flows

The effusive-explosive eruption of the volcano continues at very elevated levels, following the intense activity already present during the past few days.
According to the Semeru volcano observatory of Indonesia's volcano monitoring agency (PVMBG), this activity has now entered the stage of producing pyroclastic flows, recorded since 28 November. Pyroclastic flows are hot avalanches of fragmented hot material, both large and small (ash) particles, extremely mobile as they mix with volcanic gasses and ambient air to become gravity-driven currents reaching high velocities.
These also called "block-and-ash flows" are likely caused by gravitational collapse of the lava dome in the inner summit crater as well as the lava flow on the steep slope of the volcano. They have been traveling over the southeastern slopes and formed huge secondary ash clouds (so-called phoenix) clouds, as can be seen in the images.
Earlier today, a very high eruption column was recorded tonight at about 03:00 local time that reached approx. 50,000 ft (15,200 m) altitude and drifted SW.
Additionally, seismic instruments recorded increasing seismic activity related to volcano-tectonic earthquakes at regular intervals of 10 per day.
The warning bulletin states that ballistic impacts of volcanic bombs and pyroclastic flows could affect an area of about 1 km distance from the main crater and 4 km on the SSE flank.
Source: Pusat Vulkanologi dan Mitigasi Bencana Geologi volcano activity update 1 December 2020