Fagradalsfjall volcano update: Lava overflows building shield around main vent, ash venting

Although activity might seem to have been less vigorous during much of the past week compared to earlier stages, the eruption continues. Lava effusion rate has been at least stable if not following an overall slowly increasing trend, as last week's published data from the Icelandic Meteorological Office shows (see previous post).
After a few days with little visibility of the volcano, clouds cleared yesterday and showed that significant amounts of new lava had been erupted into the growing shield around the main vent, which in turn now seems smaller.
At about 9:30 p.m. yesterday, a prolonged lava overflow began as the lava level in the crater rose, producing small fountains, and large amounts of lava over-spilled onto the sides. Similar episodes are likely to have occurred during periods of bad weather as well.
Another lava flow made its way towards the Natthagi valley, which continues to be more and more filled as well. The flow stopped at around 2 a.m. Around 3:40, an ash cloud was seen rising from the vent, and tremor fell significantly at the same time. This lasted approx. 12 minutes and similar but smaller events with ash venting occurred several times later on.
What caused this change is not completely clear, but one likely scenario is that the magma column dropped temporarily and caused internal collapses in the emptied parts of conduits.