Acoustic emission prior to rockbursts and earthquakes
Acoustic emission prior to rockbursts and earthquakes
复制标题
DOI：
--
复制
发表时间：
1969-06
影响因子：
3
通讯作者：
B. Armstrong
中科院分区：
文献类型：
--
作者：
B. Armstrong
根据有关地震前动物躁动的流行报道，对地震前声应变和断裂辐射发射的可能性进行了半定量研究。此类排放已在实验室和矿山中观察到，并讨论了这些报告对动物行为报告的影响。在可获得定量数据的范围内，讨论了人类和动物的听觉/振动反应的比较。理论估计是根据高应力区域初步压裂发出的声音频率得出的。矿山岩爆条件的结果与观测信号的频谱一致。在地震条件下的应用表明，在高可听到低超声波频率上应该发生一些发射。还获得了对这种发射强度的估计，以确定它是否可以在实践中被检测到。这些结果导致传输范围估计，对于常压下的岩石 Q 值，表明传输范围非常短，在某些非常有利的情况下最多只有边际的检测可能性。然而，由于已知岩石 Q 值随压力而增加，因此有人指出，这可能导致高应力区域内局部传输范围的大幅增加。这种效应可能允许对应变场延伸到地表的浅层地震的初步发射进行实际观察。
On the basis of popular reports of animal agitation prior to earthquakes, a semiquantitative study has been carried out of the possibility of the emission of acoustic strain and fracture radiation prior to earthquakes. Such emission has been observed in the laboratory and in mines, and the bearing of these reports on the animal behavior reports is discussed. The comparative auditory/vibration response of humans and animals is discussed insofar as quantitative data are available. Theoretical estimates are derived of the frequency of the sound emitted by preliminary fracturing in a highly stressed region. The results for rockburst conditions in mines are consistent with the frequency spectra of the observed signals. Application to earthquake conditions indicates some emission should occur over high audible to low ultrasonic frequencies. Estimates of the intensity of such emission are also obtained to ascertain if it might be detectable on a practical basis. These results lead to transmission range estimates which, for rock Q-values at normal pressure, indicate a very short range with at best a marginal possibility of detection under certain very favorable circumstances. Since, however, rock Q-values are known to increase with pressure, it is pointed out that this may lead to a substantial increase in local transmission ranges within regions of high stress. This effect might permit the practical observation of preliminary emission for shallow earthquakes whose strain fields extend to the surface.