Gravity variation around Shinmoe-dake volcano from February 2011 through March 2012—Results of continuous absolute gravity observation and repeated hybrid gravity measurements

Abstract

We report here on continuous absolute gravity measurements made between February 2011 and March 2012 and repeated relative gravity measurements in the vicinity of Shinmoe-dake volcano, which commenced erupting in late January 2011. We find that 20 of 24 eruptive events are associated with precursory short-term gravity decreases occurring over 5-6 hours followed by quick recoveries lasting 1-2 hours. Also evident are significant long-term gravity changes arising principally from hydrological processes around the volcano, where annual precipitation exceeds 5,000 mm. To isolate the gravity signal associated with volcanic processes, we compared gravity measurements made at 15 sites in March 2011 and again in March 2012. The gravity changes and crustal deformation observed during the one year period are well explained by 6 × 10 6 m 3 inflation of a magma reservoir at a depth of 9 km and intrusion at shallower depths of a dike with dimensions of 10 km × 0.5 km × 0.5 m.

A new type of compact gravimeter for long-term absolute gravity monitoring

“…For example, volcanic activities usually relate to gravity variance. Scientists find that most volcanic eruptive events are associated with precursory gravity decreases occurring over 5-6 h followed by quick recoveries lasting 1-2 h [10]. The amplitude of absolute gravity changing before volcanic eruption could be 10 µGal 3 .…”

Participation in the absolute gravity comparison with a compact cold atom gravimeter

“…Besides, volcanic activities may be predicted by continuous absolute gravity measurements. Scientists found that quick gravity decreasing and recovering of about 10 μGal occurred before most volcanic eruption events [2] . On the other hand, accurate absolute gravity measurements also play an important role in hydrological observations.…”