Correlation between magma chamber deflation and eruption cloud height during the 2011 Shinmoe-dake eruptions

Abstract

Multiple observations of subsurface and surface phenomena during volcanic eruptions provide important information about eruption styles, eruption column dynamics, and magma plumbing systems. During the 2011 eruptions of Kirishima-Shinmoe-dake volcano in Japan, borehole-type tiltmeter data and weather radar data captured the subsurface and surface phenomena, respectively; the tiltmeters detected deflation of a magma chamber caused by migration of magma to the surface, and the weather radar detected changes in the height of the eruption cloud echo. In this study, we present a method based on the correlation between magma chamber deflation and cloud echo height to identify eruption styles. The method can detect whether a column-forming eruption is accompanied by magma migration from the magma chamber (e.g., sub-Plinian eruption), or not (e.g., Vulcanian explosion). By using well-correlated chamber deflation and echo height data, we found that eruption column dynamics during the Shinmoe-dake eruptions are well described by a one-quarter power scaling relationship between cloud height and magma discharge rate, and that a clear correlation between geodetic volume change of the magma chamber and the erupted volume indicates a stable magma plumbing system connecting the magma chamber and the surface.

Seismic and infrasonic eruption tremors and their relation to magma discharge rate: A case study for sub‐Plinian events in the 2011 eruption of Shinmoe‐dake, Japan

“…Shimbori et al [] determined eruption column heights at a radar reflectivity factor threshold of 12 dB Z . This analysis yielded time series of column heights with a 10 min sampling interval [ Shimbori et al , ; Kozono et al , ]. The radar at Kagoshima airport, 20 km away from Shinmoe‐dake, had a better temporal resolution (6 min per scan).…”

“…Therefore, the column height estimates from the airport radar are lower than those from the weather radars [ Shimbori et al , ]. Because of this problem, Kozono et al [] used column heights from the weather radars to estimate magma discharge rates. On the other hand, Takagi et al [] compared height estimates from the airport radar with infrasonic power to investigate the possibility of a relationship like , an analysis for which the better time resolution of the airport radar was critical.…”

“…Geodetically estimated magma supply rates ( ) have been compared with magma discharge rates inferred from plume heights ( H ) determined by weather radar in some recent eruptions. In spite of the uncertainties and unsteady conditions of eruption, temporal changes of and H hold a relation similar to those in equations and fairly well [ Hreinsdóttir et al , ; Kozono et al , ].…”

“…Shinmoe‐dake, in southern Kyushu, Japan, produced three sub‐Plinian eruptions in 2011. For each eruption, plume height was measured by radar [ Shimbori et al , ], was well constrained by GPS and tiltmeter data [ Ueda et al , ; Kozono et al , , ], and seismic and infrasonic signals were recorded by a regional observation network. Recently, it has been found that for some eruptions seismometers record mainly acoustic eruption tremor [ Ichihara et al , ; Nakamichi et al , ], which means that distinguishing the acoustic contribution to the seismic signal is essential in considering the relations among SET, AET, and .…”

From magma ascent to ash generation: investigating volcanic conduit processes by integrating experiments, numerical modeling, and observations

“…Furthermore, strong assumptions on the rheological/mechanical parameters of the host rock (such as elasticity) are necessary to obtain information on pressurization. Correlations between surface deformation and flux measurements from plume height have been observed for the 2010 Grímsvötn eruption, Iceland [Hreinsdóttir et al 2014] and applied in Japan [Kozono et al 2014], and this may be useful in future eruptions. In addition, surface deformation and gravity measurements can be coupled to constrain the nature of the pressurization source [e.g., Bagnardi et al 2014, Carbone et al 2015, or the magma reservoir processes responsible for variations in volume within the plumbing system , Parker et al 2016.…”