REPEATED MICROGRAVITY OBSERVATIONS, GPS SURVEY AND CONTINUOUS TILT MEASUREMENTS IN KUJU VOLCANO, CENTRAL KYUSHU, JAPAN

摘要

Observations of gravity, GPS and continuous tilt change were conducted after the 1995 eruption of Kuju volcano. There are 16 gravity observation points, 5 GPS observation points and 1 continuous tilt observation point. Gravity decreases (to a total of-90 micro-gals) were detected from 19 October 1995 to 13 January 1996 around new craters created by the eruption. From December 1997 to May 2001 the gravity increased in the area of the new craters and pre-existing fumarolic fields. An assessment of underground mass balance showed that the recharge of ground water increased gradually about three months after the eruption. The underground water flow is gradually reaching a new equilibrium state.