Tilt record from summit tiltmeter at Uwekahuna vault.

Tilt record from summit tiltmeter at Uwekahuna vault. Tilt is recorded in microradians; one radian equals 57.3 degrees. (For those unfamiliar with tilt units, one microradian is roughly the tilt created by inserting a dime beneath the end of one-kilometer-long beam.) The tilt record shows the abrupt inflation of Kilauea's summit area soon after the seismic swarm began, followed by deflation as a slug of magma moved from the summit to the Pu`u `O`o vent area, and finally recovery of the summit area to its pre-surge level.