Application of sequential fragmentation/Transport theory to deposits of 1723 and 1963-65 eruptions of Irazú Volcano, Costa Rica: Negative dispersion case

[摘要] Sequential fragmentation/transport theory (SFT) was used to analyze tephra deposits of the two main recent explosive eruptions from Irazú volcano, the 1723 and 1963-65 events. The final results provide a new way to analyze fragmentation and transport processes, which fix well with the field observations made by Alvarado (1993). A new way to process fragmentation/transport revealed 4 phi ranges that can be associated to initial volcanic fragmentation. The SFT fragmentation coefficient method is expanded to include all 5 subpopulations, allowing to compare the 1723 and 1963-65 events. SFT interpretation of 1723 eruptions is in good agreement with the volcanological description of such explosive events, whereas SFT points to a more complex 1963-65 eruption, probably due to volcanic recycling and sedimentary reworking as it is observed in the field.

[学科分类] 地质学

[关键词] Sequential fragmentation/transport;1723 and 1963-65eruptive units;Irazú volcano;Costa Rica;Volcanic Explosivity IndexResumen La Teoría de Fragmentación y Transporte Secuencial (SFT) fue aplicada a los depósitos de las dos erupciones explosivas más importantes y recientes del volcán Irazú;los eventos de 1723 y de 1963-65