...the unnamed bulge was created because of a big cavity, estimated to be about 4.5 miles below the surface, that is filling with fluid.
The fluid is likely magma, but could also be water. It was described in the report as a lake 1 mile across and 65 feet deep.
Eh? A lake one mile across and 65 feet deep? 4.5 miles below the surface? That is a REALLY poor way to describe it, seeing as many people already believe that water is found in giant underground lakes instead of in pore spaces of rocks. Maybe this could be a better way to put it: "The amount of fluid causing the earth to bulge would fill a lake one mile across and 65 feet deep."
If that's what is even meant in the report. It's terribly unclear, and misleading to boot. And I'm probably one of about sixteen people in the world who even care.