5:15 PM - 6:30 PM
[MIS03-P02] Detection of precursory anomalies using the four -component borehole strain meter (SKZ-1)
Keywords: strain meter, pre-seismic anomalies, detection method
Here we present analyses of anomalous variations detected by use of the correlation coefficient of two independent plain strain components before two major earthquakes near the network: YiLiang M5.7earthquake and LuDian M6.5 earthquake. In the imminent sage of the Yiliang earthquake, obvious strain anomalies with periods of several days, several weeks appeared simultaneously in four components at the nearest YiLiang site of the epicenter distance15.5km. The correlation coefficients for those anomalies are well below reaching 0.2 compared with the ordinal value 1.0. At DaGuan site of larger distance 30km, there appeared no significant anomalies with the factor remaining the normal value near 0.99 or so. Analyses show that the correlation coefficient can be used to objectively detect anomalies to define the successive stage of earthquake occurrence from normal to relaxation stages.
A multiple observations using the four component strain meters, groundwater meters and electromagnetic sensor are expected to substantially contribute to investigation of the nucleation process of natural earthquakes. Present finding may contribute to efficient data analysis to detect candidate of anomalies from using big amount of continuous multiple data with higher sampling rate.