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地震原理新论——兼述地震预测的科学基础

On the novel principle of earthquake and its predictability

  • 摘要: 地震是给人类造成巨大损失的自然灾害,地震预测是社会广泛关注的重大的科学问题。然而,地震机理还远未认识清楚,当前国际地震界的主流观点认为地震是不可预测的。本文以物理学的新观念为基础, 从新的视角研究地震孕育和发生过程, 提出了对地震原理的新认识, 剖析了地震不可预测论的错误。地震不可预测论产生的根源在于对地震原理的不正确认识以及对自组织临界性的误解。地震具有自组织临界性的特征, 表明不可能对地震作中长期预测, 但短期预测应是可能的。成功预测的前提包括:对地震原理的正确认识, 获得足够的特征前兆信息, 并且掌握相关的地质资料。传统地震学基于固体连续介质理论, 认为地震是地壳岩石的脆性破裂造成, 用所谓“弹性回跳”来表述地震发生机制。此观点与实际观测严重不符, 无法解释诸多地震现象, 自然也不能正确地获取和理解地震前兆信息, 因而得出地震不可预测的结论。作者根据地壳由岩石层块和其间断层泥组成这一基本事实, 将地壳作为离散态体系处理, 用颗粒物理原理认识地震孕育过程。获得的认识是:构造力以力链的方式传播, 岩块以滞滑移动的方式运动。另一方面, 在认真分析地壳岩石强度和构造作用力随深度分布规律基础上,提出地震发生的物理机制是岩石的塑性滑移和岩块运动的堵塞—解堵塞转变。对地震原理这些新认识, 可解释传统地震学无法理解的很多地震学现象, 例如, 消解了传统的“弹性回跳”原理所遭遇的“热流佯谬”, 解释了深源地震的成因等。基于对地震原理的新认识, 提出了如何正确获取地震前兆信息, 实现地震短期预测的途径。

     

    Abstract: Earthquake is a natural disaster that causes enormous loss to human society.Earthquake prediction is a major challenge to scientists from seismology and other relevant fields.However, the mechanism of earthquake is far from clear, and the mainstream view in the international seismology community is that earthquake is unpredictable. Based on some new concepts and knowledge from physics, the current article scrutinizes the gestation and occurrence of earthquake from a novel perspective, formulates a rational mechanism for earthquake. It is dissected that the basis of the erroneous cognition of earthquake unpredictability originates in misconceptions about the seismic principles and in a misunderstanding to the self-organized criticality. Earthquake is indeed consistent with the laws of self-organized criticality, that it is in principle impossible to make a medium-or long term prediction, yet the short-term predictability for earthquake should not be excluded. Prerequisites for a successful short-term earthquake prediction are as follows: a correct understanding to the principle of earthquake, availability of sufficient precursors pertinent to earthquake gestation and occurrence, geological data at large concerning the regions of interest. Traditional seismology is based on the continuous solid medium assumption, by which earthquake is attributed to the brittle fracture of rocks, as summarized in the concept of elastic rebound. This viewpoint is not at all in accordance with actual observations, unable to explain a lot of earthquake phenomena, and furthermore unable to establish truly pertinent earthquake precursors,consequently it concludes the unpredictability of earthquake. As the crust is composed of rock blocks and fault gouges there between, it must be treated as a discrete system, and knowledge of granular matters can be applied to understand the gestation and triggering of earthquakes. The fundamental picture for a seismogenic process is that the tectonic forces are transmitted in a form of force chain and the rock blocks move in the stick-slip fashion. By carefully analyzing the distributions of the strength and the tectonic force upon the crustal rocks with depth, we formulated a mechanism of earthquake in that rock blocks flow via the plastic sliding, and the earthquake is essentially a jamming-unjamming transition confronted by rock blocks. Thus the elastic rebound as mechanism for earthquake can be abandoned. Our novel earthquake principle and the relevant understanding to the earthquake processes can explain many seismologic phenomena that usually could not be understood in terms of traditional seismology, for instance, the heat-flow paradox is resolved,and the cause of deep-focus earthquake also becomes clear. A feasible pathway to obtain the earthquake precursors correctly and to realize the short-term prediction of earthquake is also presented.

     

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