Volcanic atmospheric perturbation detected with barometer, broadband seismometer, and GNSS-TEC: Comparison with ray-tracing calculation

Abstract:

Some volcanic eruptions make violent atmospheric perturbations. The excited wave sometimes reaches to the upper atmosphere and make ionospheric perturbations like coseismic signals. Our overall aim is to clarify the feasibility of GNSS-TEC observation for volcano eruption monitoring. However, although people succeed in finding TEC signals excited by eruptions, it is not easy to compare with observed near the surface directly due to some modulation factors. They are broadly classified into three categories; (1) viscosity attenuation and wave broadening, (2) how line-of-sights penetrate wavefront, and (3) ionospheric and geomagnetic conditions. In this study, we assess the effect of the factors with a case study, the Kuchinoerabujima eruption on 29th May 2015. Kuchinoerabujima is a volcanic island on active located in the southwest of Japan. The volcano erupted on 29th May 2015, and the phreatomagmatic eruption made a two-phased atmospheric pressure change. We found the signal detected barometers, broadband seismometers, and GNSS-TEC in both near and far. The TEC signal is similar to an eruption that occurred on Asama volcano in 2004.

We reveal the energy distribution by the eruption with the ray-tracing method. The method is often used to interpret such TEC signals. However, no one reported the relationship between pressure perturbations observed near the surface and the ionospheric disturbances. We tried to reveal both of the signals and assess the effects of the modulation factors. In this presentation, we introduce the comparison results and show the method's prospects.