I see that many people think that Grímsfjall has started to deflate due to a drop in GPS measurements. But the “Up” part of the GPS measurements have been dropping over the past few days from about 85mm and down to about 65mm today.
As that may be true that the mountain has started to deflate from the top. It is not to say that deflation process has started at Grímsfjall. As the GPS data clearly shows that a inflation process has just moved from the top and to the south. But current GPS measurement clearly show that Grímsfjall is now inflating to the south (15mm today) with minor inflation to the east (about 15mm today). So it is clear that the magma is moving inside the volcano from one location to a other over the past few days. What that means is unclear at the moment. But it appears that the inflation to the south is speeding up at current time. This might get interesting soon in my opinion. Regardless if there is a eruption or not.
Data: ISGPS GFUM
Vatnajökull continued GPS data project from 2004.
According to GPS data from GPS station located on top of Grímsfjall the volcano continues to inflate. Now it is about 80mm and does not seems to go much higher then that for some reason. Since Grímsfjall has stopped to inflate up at the moment it is currently inflating in other directions. The automatic GPS data clearly shows that the inflation is now moving south but is interestingly is holding it east-west movement. I am not clear on why that is the case at the moment.
Data: GFUM ISGPS
Over the past two days the GPS station on Grímsfjall has been reporting some interesting data on what is going on inside Grímsfjall. But it appears that Grímsfjall is inflating at really fast speed at the moment. The movement is mostly upwards, as the station is located on the top of the mountain.
Currently the GPS station at Grímsfjall is reporting about 85mm movement upwards and about 5mm movement north (moving south). At last the movement east is about 10mm. But that gives the expansion site close to the GPS station, I would estimate rather rudely about 5 to 10 km from the SIL and GPS location. But it might be closer or longer. This is just a badly educated guess that I am doing here.
It is clear that if Grímsfjall continues to inflate at the same rate and it has been doing for the past few days and weeks it is going to erupt real soon. When is a good question as always.
Data: ISGPS GFUM