[Geology2] Part of El Hierro's El Pinar inflated 2 CM or almost 0.8 inch today - GPS measurements

"An inflation by about 2 cm has become visible on the latest GPS measurements at the station located in El Pinar, i.e. in the area where most of the quakes are now occurring. There is no sign of an end of the swarm. So far, there are more than 130 quakes registered today and their number (including many smaller ones) is likely to be above 200 at the end of today. Epicenter depth is remaining at about 22 km depth and there is a weak tremor signal from time to time as well. 
It will be interesting to see when or if magma decides to move upwards."

Why does magma sometimes move upwards after inflating the ground?

Magma forms from partial melting of mantle rocks. As the rocks move upward (or have water added to them), they start to melt a little bit. These little blebs of melt migrate upward and coalesce into larger volumes that continue to move upward. They may collect in a magma chamber or they may just come straight up. As they rise, gas molecules in the magma come out of solution and form bubbles and as the bubbles rise they expand. Eventually the pressure from these bubbles is stronger than the surrounding solid rock and this surrounding rock fractures, allowing the magma to get to the surface.