全球主要火山灾害及其分布特征

本文研究了火山灾害各种致灾因子的物理过程和灾害特点,根据文献中记载的全球火山灾害,在进行火山灾害分区研究的基础上,研究了全球火山灾害分布特征.全球主要的火山灾害分布在8个主要区域.有记载的火山灾害在热带占73%,远高于火山喷发分布于热带区的比例.全球两个最强烈的火山灾害分布区都是围绕着位于板块结合部表现为复杂构造结的班达海和加勒比海,而且每一个灾害区都有3条分支.热带区第3个灾害区为中非区,地幔上隆是这里主要的动力学背景.本文还研究了1700年以来火山灾害时间分布特征,以及1993年以来各种火山灾害发生频次.

GLOBAL DISTRIBUTION OF VOLCANIC HAZARDS

Volcanic hazards have different types and risk factors, such as tephra falls, lava flows, pyroclastic flows, gases, lahars, avalanches and tsunamis. In this paper we discuss the physical processes and special disaster. Based on the catalog of active volcanoes of the world and volcano eruption database,the patterns of global distribution of volcanic hazards waere studied in this paper. Global volcanic hazards are mainly distributed in 8 regions: Southeast Asia Hazard Region, Middle America Hazard Region, Middle Africa Hazard Region, East Asia Hazard Region, North America Hazard Region, North Europe Hazard Region, New Zealand Hazard Region and South America Hazard Region. The features of volcanic hazards in these regions are depicted. Statistics of recorded volcanic hazards are showed as the distribution of hazard numbers with latitudes and longitudes. A majority of volcanic hazards took place in the tropic area, that accounts for 73% of hazard records around the world, much higher than the proportion of the volcano eruptions. The most intense volcanic hazards occurred in two tropic areas, each consists of three branches, and both are tectonic complex situated on the conjunction of plates, and surrounding a margin of sea: Banda Sea in Southeast Asia Hazard Region and Caribbean Sea in Middle America Hazard Region. The third region in the tropic area is the Middle Africa Hazard Region with mantle plume as its own geodynamic background.The temporal distribution was studied in this paper. The hazard types are different, some volcanoes cause some certain hazards, and others have various forms of hazard. Mild volcanic hazard takes place several tens times every year. Severe volcanic hazards are rare in the history, 6 events with more than 10 000 deaths occurred in recent 300 years. The time intervals of these severe fatalities are different: the short one is less than 10 years, and the longest one is over 80 years.Most volcanic hazards in China were localized around the craters; the dominant activities were lava flow and small-scale eruptions. In China, Chanbaishan Tianchi Volcano had the largest hazard in the history, and is the most dangerous volcano with potential eruption in the future.The formation and distribution of volcanic hazards have their special characteristics. A better understanding of the different distribution between volcano eruptions and volcanic hazards is necessary for integrated volcano hazard mitigation, such as hazard zoning, volcano eruption warning, and emergency evacuation.