Capturing Transient Mass Changes for the 2011 Tohoku Tsunami on a Spring Gravity Meter.

The 11 March M_w 9.0 Tohoku earthquake (5:46 UTC) produced severe damage in northern Honshu, Japan, and generated a tsunami which devastated Japan's northeast coast and impacted most of the Pacific basin. Distal tsunami waves approaching 0.5 m peak-to-peak were recorded at Tauranga, New Zealand, beginning ~19:00 UTC. A contemporaneous 6 μ Gal peak-to-peak oscillation was observed on a continuously recording spring gravity meter located at White Island volcano, about 90 km northeast of Tauranga. We modeled the gravity oscillation by application of a tsunami wave-field simulation, which incorporates theoretical Tohoku earthquake source-rupture time history and local White Island bathymetry. The simulation yielded discrete wave heights that were converted to a theoretical gravity response and that agreed with the observed gravity oscillation. The successful capture of tsunami waves by a spring gravity meter may have implications for improving tsunami modeling from distal tsunami waves. [ABSTRACT FROM AUTHOR]