10:45 AM - 12:15 PM
[MIS21-P07] Experimental verification for self-organization process on the spatial distribution of rootless eruption
Keywords:rootless eruption, analog experiment, Mars
Rootless eruption is a continuous explosion by lava-water interactions (e.g., Thorarionson, 1951; 1953). The ejected pyroclasts form conical edifices so-called rootless cones. Since subsurface water plays an important role in rootless eruptions, the existence of rootless cones has been focused on as evidence of subsurface water in the recent past (e.g., Greeley et al., 2001). The spatial distribution of rootless cones has been considered aligned by the self-organization process, in which the availability of water consumed in rootless eruptions controls the spacing/density of cones (Hamilton et al., 2010). The self-organization process is derived from actual field data and theory, however further verification from experimental approaches is necessary.
In this study, we performed analog rootless eruption using heated syrup, baking soda, and cake syrup, as developed by Noguchi et al., 2018. The basic procedure for our experiment is similar to that in a karumeyaki; heated syrup (as an analog of lava) was poured onto substrates of baking soda-cake syrup mixture (as an analog of water-logged sediment). Baking soda (sodium bicarbonate, NaHCO3) thermally decomposes into sodium carbonate (Na2CO3), water (H2O), and carbon dioxide (CO2). The emission of CO2 gas can be regarded as an analog of water vaporization by lava-water interaction. In preliminary experiments, we found some vents failed to break through the upper syrup layer by surrounding vents and became short. Therefore, in this experiment, we measured the number/crosscut areas of vents, the mass changes by CO2 emission, and the number of short vents (hereafter, loser vents).
In our experiments, the amount of CO2 emission had no relationship with the amount of poured heated syrup. Since the density of the heated syrup is smaller than that of the substrate, the boundary area between the heated syrup and the substrate was thought to be constant (i.e., no Rayleigh-Taylor instability worked). The number of the loser vents increased with the amount of poured heated syrup. The sum number of vents and loser vents was regarded as constant with the change in the amount of poured heated syrup.
In this presentation, we discuss our results and the role of the vent-merge effect in the self-organization of rootless eruptions.
In this study, we performed analog rootless eruption using heated syrup, baking soda, and cake syrup, as developed by Noguchi et al., 2018. The basic procedure for our experiment is similar to that in a karumeyaki; heated syrup (as an analog of lava) was poured onto substrates of baking soda-cake syrup mixture (as an analog of water-logged sediment). Baking soda (sodium bicarbonate, NaHCO3) thermally decomposes into sodium carbonate (Na2CO3), water (H2O), and carbon dioxide (CO2). The emission of CO2 gas can be regarded as an analog of water vaporization by lava-water interaction. In preliminary experiments, we found some vents failed to break through the upper syrup layer by surrounding vents and became short. Therefore, in this experiment, we measured the number/crosscut areas of vents, the mass changes by CO2 emission, and the number of short vents (hereafter, loser vents).
In our experiments, the amount of CO2 emission had no relationship with the amount of poured heated syrup. Since the density of the heated syrup is smaller than that of the substrate, the boundary area between the heated syrup and the substrate was thought to be constant (i.e., no Rayleigh-Taylor instability worked). The number of the loser vents increased with the amount of poured heated syrup. The sum number of vents and loser vents was regarded as constant with the change in the amount of poured heated syrup.
In this presentation, we discuss our results and the role of the vent-merge effect in the self-organization of rootless eruptions.