Data obtained from the Shinjima Seismic observation well

Table S1. Refractive index values of orthopyroxene and volcanic glass from the Shinjima Seismic Observation Well and the values reported for key tephras in the inner area of Kagoshima Bay.
Table S2. XRF analyses of the pumice and lithic clasts of the Susaki Pumice, Shinjima Pumice, and unnamed tephras from the drill cores of the Shinjima Seismic Observation Well.
Table S3. Diatom fossils identified in the drill cores of the Shinjima Seismic Observation Well.
Table S4. Accumulation rates of post-caldera sediment in the Shinjima Seismic Observation Well.
Fig. S1. History of stratigraphic division of the sedimentary succession exposed on Shinjima Island .
Fig. S2. Photographs showing the mode of occurrence of Facies PLT. Inverse grading of pumice lapilli is likely a diagnostic feature of subaqueous eruption-fed density current deposits. The main part of the facies is overlain in part by normally graded ash and laminated fine ash, suggesting a transition to volcaniclastic turbidites by the ingestion of ambient water during the flowage.
Fig. S3. Photographs showing the mode of occurrence of Facies GPLT.
Fig. S4. Photomicrographs showing the mode of occurrence of pumice and dense rock clasts in drill cores of Facies GPLT collected at depths of 318–319 m in the Shinjima Seismic Observation Well.

表 S1：信濃島地震观测井中正方辉石和火山玻璃的折射率值，以及针对鹿儿岛湾内陆关键火山碎屑流报告的值。表 S2：对须崎火山玻璃、信濃岛火山玻璃及信濃岛地震观测井岩芯中未命名火山碎屑流火山玻璃和岩石碎块的 XRF 分析。表 S3：信濃岛地震观测井岩芯中识别出的硅藻化石。表 S4：信濃岛地震观测井中后火山口沉积物的累积速率。图 S1：信濃岛岛上出露的沉积层系地层划分的历史。图 S2：展示 Facies PLT 存在方式的摄影。火山玻璃粒的逆序分级可能是水下喷发供能密度流沉积物的诊断特征。该相的主要部分部分被正常分级的火山灰和层状细火山灰覆盖，表明在流动过程中通过吸收环境水转变为火山碎屑浊流。图 S3：展示 Facies GPLT 存在方式的摄影。图 S4：展示在信濃岛地震观测井 318-319 米深处采集的 Facies GPLT 火山玻璃和致密岩石碎块的显微照片。