Presentation Information
[O03-P73]Estimation of sedimentary environment of volcaniclastic deposit and location of craters in the Nomashi formation, Izu Oshima
*Kouki Aida1 (1.Musashi High School and Junior High School)
Keywords:
Izu Oshima volcano,Younger Oshima group,tephra thickness,scoria coarseness,wind direction of eruption,location of volcanic crater
Izu-Oshima is an active volcano located in the northern end of Izu archipelago. Its eruptive history has been made clear by observing its outcrops. Most of the real surroundings of each eruption such as weather condition and location of crater remains to be confirmed.
In order to clarify the sedimentary environment of eruptions, we investigated the exposures on Mabushi logging road crossing in an east to west direction on the southern part of the island. On this road, we could observe the Younger Oshima group, which is the upper part of rocks in Oshima. In this study, we narrowed down a survey into the Nomashi formation, which is the middle part of the Younger Oshima group. As a result of correlation, we revealed that some of the same layers have laterally continuous variation of thickness and scoria coarseness. We suggest that continuous thickness variation shows the approximate wind direction of the eruption, and continuous scoria coarseness variation shows the approximate location of the craters.
In order to clarify the sedimentary environment of eruptions, we investigated the exposures on Mabushi logging road crossing in an east to west direction on the southern part of the island. On this road, we could observe the Younger Oshima group, which is the upper part of rocks in Oshima. In this study, we narrowed down a survey into the Nomashi formation, which is the middle part of the Younger Oshima group. As a result of correlation, we revealed that some of the same layers have laterally continuous variation of thickness and scoria coarseness. We suggest that continuous thickness variation shows the approximate wind direction of the eruption, and continuous scoria coarseness variation shows the approximate location of the craters.