全球火山活动分布特征

GLOBAL VOLCANO DISTRIBUTION:PATTERN AND VARIATION

根据全球活动火山目录 ,分析研究了全球火山分布的特征 ,描述了各区的火山活动分布 ,总结了火山活动强度的时、空分布特征。全球火山活动可分为三大区 ,西太平洋火山活动区 ,主要与太平洋板块向北西西方向的俯冲活动有关 ;东太平洋火山活动区 ,主要与太平洋东面的小板块 (胡安德富卡板块、科科斯、纳斯卡板块 )向美洲板块的俯冲有关 ;大西洋火山活动区 ,与大西洋和非洲的裂开 ,以及地中海带的活动有关。不同火山区带具有各自的最大喷发等级与相应的复发周期。一条火山弧上活动强度的分布往往是不对称的 ,意味着火山弧在整体上有其动力学的控制机理。火山活动显示了随纬度成带状分布。在 - 10～ 0° ,10 2 0° ,30 4 0°,5 0 6 0°分布有高值带。火山喷发活动还与当地的重力势有关 ,重力势正异常可能与高的正压力有关 ,有利于产生特大喷发。火山活动与大角度的正面俯冲带的弧后火山活动最强 ,当板块运动方向与板块边缘走向成小角度相交时 ,缺少正面俯冲的动力 ,火山活动相对平静。

Based on the global catalogue of Holocene volcano and Volcano Eruption Database(NOAA), the patterns of global volcano distribution are studied in this paper. The global volcano distribution can be divided into three areas: a) West Pacific Area: most volcanism are correlated with NWW subduction of Pacific Plate; b) East Pacific Area: most volcanism are correlated with some small plates (Juan de Fuca, Nazca, Cocos), east to the Pacific Plate, subducted beneath the American Plate; c) Atlantic Area: most volcanism are correlated with rift of Atlantic and Africa, and with the active dynamic process in the Mediterranean. The spatial-temporal distribution of volcano magnitude has been analyzed, and some major features are described. A volcano area consists of a few volcanic zones that are composed of volcanic arcs. There are different maximum magnitude and corresponding recrudescent periods in different volcanic zones. The distribution of intensity is asymmetrical in most volcanic arcs, which implies a comprehensive dominative mechanism existing in each volcanic arc. The distribution of the number of active volcanoes appears a zonal pattern: relative peak values present in the latitude of 10~20°,30~40°,50~60° north and 0~10° south. The volcanic eruptions are correlated with geoid, the positive geoid anomaly can build up high normal stress, which is in favor of huge eruptions. The volcanic arcs behind a normal subduction zone have strong volcanism, whereas the volcanic arc related with a transpression zone has relatively volcanisom.