【摘要】 孕震、发震过程中往往存在地电异常现象,但其异常机理尚未得到统一认识。目前大多数地震科学工作者主要持有两种观点,即"压电效应模式"和"扩容-膨胀模式(即D-D模式)",但这两种观点都存在一定局限性。基于前人关于各类成因天然磁铁矿热电效应的研究,从宏观角度对含有磁铁矿的岩石进行了热电效应实验研究。实验选择含磁铁矿黑云母石英片岩(磁铁矿体积含量为10%～12%)作试件,样品大小为80mm×80mm×12mm长方体。实验过程中将样品置于莫来石高温绝热砖砌筑的单向加热炉之上,样品上方约10cm处设置铝板作感应电荷载体,以高精度万用表记录热电势差。单向炉加热制度约为40℃/分钟。实验结果表明:单向加热条件下,含磁铁矿黑云母石英片岩能够产生显著热电势。其中,室温至500℃加热条件下,去除各种环境噪声后在温度降方向距样品约10cm～11.5cm空间内能够产生约0～25mV的电势降。这一结果暗示,孕震、发震过程中产生的地热异常则可能激发地壳内含有磁铁矿的岩石产生热电效应,从而导致背景地电场产生异常现象。更多还原

【Abstract】 There is no consensus on the mechanism of abnormal geoelectric anomaly during the course of earthquake preparation and occurrence.Two hypothetical modes(the piezoelectric effect mode and the Dilatancy-diffusion(D-D) mode) were previously proposed to interpret the anomaly.However,both interpretation modes have limitations to some extent.Based on previous studies on thermoelectricity of natural magnetite of various origins,this paper examines the thermoelectric effect of rocks containing magnetite minerals in a macroscopic perspective.Magnetite-containing biotite-quartz schist(magnetite volume content is 10%~12%) is chosen as a cuboid test piece of 80 mm× 80 mm× 12 mm.In the testing process,the cuboid is placed atop a single-track heating furnace made from high-temperature refractory,an aluminium sheet is placed 10 cm over the testing piece to serve as the carrier of induced charges.A high-precision multimeter is used to record thermoelectric potential difference.The heating rate of the single-track heating furnace is about 40 ℃/minute.The results show that magnetite-containing biotite-quartz schist can generate conspicuous thermoelectric potential on the single-track heating condition.When the temperature is increased to 500 ℃ and environmental noises are eliminated,10 cm~11.5 cm away from the testing piece in temperature drop direction can generate about 0~25 mV potential drop.It suggests that geothermal anomaly which arises during earthquake preparation and occurrence has the potential to affect magnetite-containing rocks within the crust and to trigger thermoelectric effect,which results in geoelectricity anomaly consequently.更多还原