火山活动规律及其影响因素初探

A tentative study on patterns of volcanic activities and their influencing factors

了解火山活动的驱动力、火山喷发在地质历史时期发生的规律对预测未来火山喷发、减少火山灾害有重要意义。本文概述了第四纪全球火山活动强度和分布特征,剖析了火山喷发的周期性及其影响因素,认为在较短的时间尺度(百年尺度)火山喷发可能和气候变化有关,并受地震和月潮周期的影响,而与太阳活动之间的相关性并不明显。在较长的时间尺度(过去2 Ma),以1000年为步长统计了有记录的陆地上的火山喷发量随时间的变化规律。通过能谱分析,发现火山喷发量存在11.1~8.6万年、5.3~4.2万年和2万年的周期,可能分别与地球轨道的短偏心率、斜率和岁差周期有关,表明火山喷发量变化可能受天文因素驱动。进一步研究发现,对于陆地上的火山,间冰期相比冰期更有利于形成大型喷发,这可能和间冰期冰融化伴随的压力卸载有关。初步研究表明,天文旋回驱动太阳辐射、气候和火山喷发量的长周期变化及其相互关系是亟待解决的科学问题,对其研究有助于预测未来大型火山的喷发规律。

Understanding the driving forces of volcanic activity and the laws that govern the occurrence of volcanic eruptions during geological history is of significance for humans to predict future eruptions and reduce volcanic hazards.This study provides an overview of the intensity and distribution of global volcanic activity during the Quaternary,and summarizes the periodicity of volcanic eruptions and their influencing factors.We suggest that on shorter timescales(hundreds of years)volcanic eruptions may be influenced by climate change,earthquakes,and lunar tidal cycles,whereas their correlation with solar activity is not obvious.On longer timescales(2 Ma),we counted the temporal variations of the volumes of subaerial volcanic eruptions in the LaMEVE database in steps of 1,000 years.Through energy spectral analysis,we found that there are cycles of 111 and 86 kyrs close to the short eccentricity cycle,53 and 42 kyrs close to the obliquity cycle,and 20 kyrs close to the precession cycle.These periodicities suggest that changes of eruption volume may be driven by astronomical factors.Our further studies found that for terrestrial volcanoes,interglacial periods are more favorable for large-scale volcanic eruptions than glacial periods,which may be related to the pressure unloading accompanying ice melting during deglaciation.Our preliminary study suggests that the long-period changes in solar radiation,climate,volcanic eruption volumes driven by astronomical cycles and their correlations are urgent scientific questions that need to be solved and can help predict the rules of large-scale volcanic eruptions in the future.