在实验室使用红外热像仪和接触式测温仪同步观测记录了压性和张性雁列断层失稳错动前后的热场变化过程.从实验记录中发现,在断层失稳引起温度场和热红外辐射亮温温度场上升之前,在两断层段之间的岩桥区发生降温变化.断层带开始升温发生在失稳前2~3s内,岩桥区的降温却发生在失稳前约20s,这两个超前时间长度相差近一个量级.此类热场先降后升变化过程在雁列构造变形中有一定的普遍性,可能作为雁列断层失稳错动的热场前兆模式.根据实验观测结果,详细描述了上述热场变化的时间过程及其空间分布特征,分析了产生此种失稳前兆模式的机制,显著异常出现的条件及有利观测部位,讨论了它在地震前兆探索等研究中的意义.
We have measured synchronously the variation of temperature and infrared radiation fields before and after stick-slip events on compressive and extensional en echelon faults by using an infrared thermal image system and a contact-type thermometric apparatus in the laboratory. From the record during the experiments we found that the temperature and thermal radiation values drop first in the inner flank of the jog before they begin to jump along the fault. The relative rising of temperature along fault occurs 2 - 3 seconds before a stick-slip, while drop of temperature in jog area happens 20 seconds before, meaning about a magnitude more time ahead. This kind of pattern "temperature drops first and rises afterwards" is ubiquitous to some extent for stick slip events during the deformation of en echelon faults. Therefore, it can be regarded as a heat precursor pattern of instability. The temporal process and the characteristics in spatial structure of thermal field are described based on the results of the experiment. The mechanism of precursory pattern is discussed. The generation condition of remarkable anomalies and favorable sites of observations for this precursory phenomenon are analyzed. Moreover, the significance in exploring of earthquake precursory and application of satellite infrared information is discussed.