Precursors for rock fracturing and failure—Part I: IRR image abnormalities

Abstract

There are many precursors, including the abnormality of infrared radiation (IRR), for rock fracturing and failure. As the comprehensive effect of rock thermoelasticity and rock friction, the study of the IRR abnormality of loaded rock, as one of the important issues of remote sensing rock mechanics (RSRM), is facilitated by the fast development of IR remote sensing imaging technology. In view of energy input and consumption by the loading system, comprised of loader, rock and air, the mechanism of surface IRR from loaded rock is studied. The concepts that surface IRR is the comprehensive effect of a series of physical-mechanical processes inside loaded rock and that the thermoelastic effect and the frictional-thermal effect are two of the main mechanisms are presented here. Based on retrospective investigation of the fundamental experiments on RSRM during the past decade, it is concluded that there are two kinds of IRR abnormality as precursors of rock fracturing and failure: IRR image abnormality and IRR temperature curve abnormality. The spatial-temporal evolution of abnormal surface IRR images of loaded rock in a condition of uniaxial stress, compressive shear, biaxial stress, frictional slide and impact is systematically analyzed. The fact that large IRR can occur in the fracturing center of compressively loaded and shearing fractured strong and brittle rock is also revealed. Finally, the relation between rock stress and IRR temperature are studied based on thermomechanical coupling theory for solid materials. It is concluded that IRR image abnormalities are important precursors for rock fracturing and meaningful for the forecast of rockbursts and tectonic earthquakes. r

Relation between the celestial tide-generating stress and the temperature variations of the Abruzzo <i>M</i> = 6.3 Earthquake in April 2009

“…3, it can be seen that the temperature rise went through such successive evolution as: initial temperature rising (on 29 March) → continued rapid rising (on 31 March) → reaching the peak (on 1 April) → weakening (from 2 to 5 April) → rising again (from 6 to 8 April, earthquake occurred) → reaching another peak (on 9 April, severe aftershock occurred) → weakening again (on 10 April). The successive evolution of temperature rise is consistent with the rock broken process under stress loading (Wu et al, 2006). In spatial, the process of a rock break under the extrusion of tectonic movement is as: micro-breaking → rupture strengthening → accumulating energy (the atresia of stress) → releasing energy → shaking → tranquilizing.…”

Geosphere coupling and hydrothermal anomalies before the 2009 <i>M</i><sub>w</sub> 6.3 L'Aquila earthquake in Italy

“…The hypocenter area is bounded by two intersecting thrusts, with the Olevano-Antrodoco thrust being the main one. The experimental TIR observations on the fracturing of loaded intersected faults revealed the close relationship between the changed TIR radiation and the geometrical structure of intersected faults, with abnormal TIR spots usually occurring along the main fault (Wu et al, 2004(Wu et al, , 2006. In addition, two separate zones of surface NTG anomalies (Fig.…”

“…With the development of Earth observation technologies and anomaly recognition methods (e.g., Wu et al, 2012;Qin et al, 2013), non-thermal anomalous variations in geochemical and electromagnetic signals from different spheres of the planet Earth may indicate complex geosphere coupling effects during the slow preparation phase of earthquakes. During the past decades, several mechanisms or hypotheses for interpreting thermal anomalies have been proposed; examples include the positive hole (P-hole) effect (Freund, 2011), transient electric field (Liperovsky et al, 2008a), frictional heat of faults (Geng et al, 1998;Wu et al, 2006), and the greenhouse effect caused by Earth degassing (Tronin et al, 2002). A unified lithosphere-atmosphere-ionosphere coupling (LAIC) model was proposed to explain the inherent links among different parameters (Liperovsky et al, 2008b;Pulinets and Ouzounov, 2011;Pulinets, 2012).…”

A Deviation-Time-Space-Thermal (DTS-T) Method for Global Earth Observation System of Systems (GEOSS)-Based Earthquake Anomaly Recognition: Criterions and Quantify Indices

“…resulting local greenhouse effect [3], underground charge generation and propagation in igneous rock with P-holes [16], near-surface air ionization due to enhanced radon emission leading to the release of latent heat [17], friction heat produced from rock fracturing and fault friction sliding [18][19][20], have been proposed to interpret the possible thermal anomaly mechanism. However, none of the above hypotheses are completely understood or fundamentally correct, since the influence of Earth coversphere (including water, ice, sand, soil and vegetation, which are quite different from the crust rock) on satellite remote sensing is inevitable and will cause great uncertainties to the earthquake thermal anomaly recognition.…”