Dynamics of Volcanic Explosion

该项目旨在更好地了解火山爆发的基本过程和机制，为减轻火山灾害作出贡献。为详细研究火山喷发，研制了可在火山口附近遥控移动和操作的“火山喷发移动观测站”，进行观测、取样和装置安装。从一些经常发生小型爆炸的火山获得的宽带地震图和空气波记录的新数据集显示，在每次爆炸之前，作为一个共同的物理过程，存在着特征性的膨胀和收缩。对火山物质的理论和实验研究已经明确了可能控制上升岩浆脱气和破碎的因素。关于岩浆上升过程的计算机模拟已经阐明了可能决定喷发爆炸性的条件，并表明爆炸性可以通过加速膨胀来预测。提出了一种混合岩浆碎片的喷发气体流的三维模拟方案，用于描述火山柱和火山碎屑流。火山喷发的尺度化和爆炸气流的模拟也为评估火山喷发的影响提供了有用的方法。综合我们的研究成果和其他一些知识，建立了一个有助于系统了解火山爆发的数据库。该数据库和本项目开发的一些计算机程序可作为模拟整个喷发过程和评估可能的火山危害的基本工具。还开发了一个web服务器，以便从火山危机的有效讨论中迅速做出决定。为公众作了一些关于火山爆发的讲座，并对我们的研究作了一些示范。一本可以向一般人解释我们的研究成果的教科书将会出版。

This project aims at better understanding of fundamental processes and mechanisms of volcanic explosions with some contribution to volcanic hazard mitigation. The "Mobile Observatory for Volcanic Explosions" that can be moved and operated for observations, sampling and device installation in the vicinity of volcanic craters with a remote control has been developed for detailed studies of volcanic eruptions. New data sets of broad-band seismograms and air-wave records obtained at some volcanoes involving frequent small explosions have revealed the presence of characteristic inflation and deflation prior to each explosion as a common physical process. Theoretical and experimental studies on volcanic materials have specified the factors that may control degassing and fragmentation of ascending magma. Computer simulations about magma ascent processes have clarified the conditions that may determine explosiveness of eruptions and have shown that the explosiveness can be predicted by accelerated inflation. A three-dimensional simulation scheme of effusing gassy flow mixed with magma fragments has been developed to describe volcanic plumes and pyroclastic flows. Scaling of explosions and simulation of explosive air flow also provide useful methods to evaluate influences of volcanic explosions.Compiling our research outcomes and some other knowledge, a database, which is useful for a systematic understanding of volcanic explosions, has been constructed. This database and some computer programs developed in this project can be basic tools in simulating the entire eruptive processes and evaluating possible volcanic hazards. A web server also has been developed for prompt decisions to derive from efficient discussions at volcanic crises. Some lectures about volcanic explosions for the public were given with some demonstration of our studies. A textbook that may explain our research results to the general people will be published.