5:15 PM - 6:30 PM
[SVC27-P08] Eruption Sequences and Precursory Activities of Large-scale Volcanic Eruptions, and Construction of Large-scale Volcanic Eruption Database
Keywords:Large-scale, Eruption sequence, Precursor activities, Caldera, Database
Volcanic hazards can occur thousands of kilometers away from the volcano due to large-scale PDCs and tephra falls produced from the VEI 5-8 class large-scale eruptions. It is thus important to reveal the past eruption sequences of large-scale eruptions and their long-term and short-term precursory activities for an effective volcanic hazards mitigation measures. Many variations can be observed for the eruption sequences of large-scale eruptions and long-term and short-term precursory activities, which generally do not follow a common pattern. The Geological Survey of Japan, AIST, started a project to compile the characteristics of eruption products, eruption sequences, long-term and short-term precursory and post-caldera activities of large-scale volcanic eruptions. The contents and website of this large-scale eruption database are introduced in this presentation.
The long-term and short-term precursory activities, eruption sequences of main caldera-forming eruption, and post-caldera activities have been currently compiled for a total of 17 large-scale eruptions. These eruptions are the 946AD Chanbaishan-Tomakomai, 6.4 cal ka Ikeda caldera-forming, 7.3 cal ka Kikai-Akahoya, 7.6 cal ka Mashu Main-caldera-forming, 14.6 cal ka Nigorikawa, 15.5 cal ka Towada-Hachinohe, 30 cal ka Aira-Ito, 32 cal ka Towada-Ofudo, 40 cal ka Kutcharo I, 46 cal ka Shikotsu, 60 cal ka Daisen-Kurayoshi, 87-89 ka Aso-4, 95 ka Kikai-Nagase, 106 ka Toya, 108 ka Ata, 110-115 ka Sambe-Kisuki and 120 ka Kutchro IV eruptions. Part of descriptions of these eruptions are published in GSJ Openfile reports (no. 680 and 699; Nishino et al., 2019, Kaneda et al., 2020a).
The precursory activities of large-scale eruptions are categorized into two types: Type I, precursor activities were observed in the last 50 ka, and Type II, no precursor activities were observed. Type I precursory activities are subdivided into 3 types based on the average eruption rates until the main caldera-forming eruptions occur: increased (Type I-1), stayed constant (Type I-2) and decreased (Type I-3) (Kaneda et al., 2020b).
We have developed a Large-scale Eruption Database website, where users can browse and search the long-term and short-term precursory activities, sequences of main caldera-forming eruptions and post-caldera volcanic activities (Figure). Map of the distributions of major eruption products are displayed which could be zoomed in and zoomed out using WebGIS technology. The distributions of tephra falls and pyroclastic flows and the shape of caldera-rims are digitized and saved in GIS format and could be shown using the system. This website will be made accessible to the public within the fiscal year 2021, together with the Plinian Eruption Database, which is also currently developed.
Figure caption: Example of the website of the Large-scale Eruption Database (Aira-Tn Ash Fall descriptions during the main caldera-forming eruption).
The long-term and short-term precursory activities, eruption sequences of main caldera-forming eruption, and post-caldera activities have been currently compiled for a total of 17 large-scale eruptions. These eruptions are the 946AD Chanbaishan-Tomakomai, 6.4 cal ka Ikeda caldera-forming, 7.3 cal ka Kikai-Akahoya, 7.6 cal ka Mashu Main-caldera-forming, 14.6 cal ka Nigorikawa, 15.5 cal ka Towada-Hachinohe, 30 cal ka Aira-Ito, 32 cal ka Towada-Ofudo, 40 cal ka Kutcharo I, 46 cal ka Shikotsu, 60 cal ka Daisen-Kurayoshi, 87-89 ka Aso-4, 95 ka Kikai-Nagase, 106 ka Toya, 108 ka Ata, 110-115 ka Sambe-Kisuki and 120 ka Kutchro IV eruptions. Part of descriptions of these eruptions are published in GSJ Openfile reports (no. 680 and 699; Nishino et al., 2019, Kaneda et al., 2020a).
The precursory activities of large-scale eruptions are categorized into two types: Type I, precursor activities were observed in the last 50 ka, and Type II, no precursor activities were observed. Type I precursory activities are subdivided into 3 types based on the average eruption rates until the main caldera-forming eruptions occur: increased (Type I-1), stayed constant (Type I-2) and decreased (Type I-3) (Kaneda et al., 2020b).
We have developed a Large-scale Eruption Database website, where users can browse and search the long-term and short-term precursory activities, sequences of main caldera-forming eruptions and post-caldera volcanic activities (Figure). Map of the distributions of major eruption products are displayed which could be zoomed in and zoomed out using WebGIS technology. The distributions of tephra falls and pyroclastic flows and the shape of caldera-rims are digitized and saved in GIS format and could be shown using the system. This website will be made accessible to the public within the fiscal year 2021, together with the Plinian Eruption Database, which is also currently developed.
Figure caption: Example of the website of the Large-scale Eruption Database (Aira-Tn Ash Fall descriptions during the main caldera-forming eruption).