6:15 PM - 7:30 PM
[SCG15-P02] Application Prospects of SKZ-1 4-component borehole strain meter
Keywords:Borehole strain, Observation technology, Pre-seismic anomaly information
The instrument feature are that it uses four sensing elements that were set at intervals of 45 degree and checking formula is simple and clear: U1+U3=U2+U4. Reliability of observation has been obviously improved because four elements are embedded in the 8 narrow ribs. Cross check degree of the data has reached 0.99.
Preliminary results: 1. M5.7 YiLiang earthquake occurred (longitude 104.00, latitude 27.5) at 11:19 on September 7th, 2012. Seven days before the earthquake, obvious strain anomaly of four directions appeared at the same time in YiLiang Seismic Station which epicenter distance is 15.5km. But in DaGuan Seismic Station which epicenter distance is 30km, correlation coefficient of the two surface strain curve is 0.99 or so, there was no significant association with this earthquake. NS and NW data signals of the borehole strain meter appeared low frequency noise 11-17 minutes before the M5.7 DaGuan earthquake, and the earthquake occurred two minutes after the end of noise. In this earthquake, what is difficult to understand is that the low frequency signal curve shape is different between the NS curve and NW curve. Cycle of NS is about 15s and the cycle of NW is about 60s. But NE, EW data curve did not appear similar situation and the relationship between the low frequency data of four components did not conform to checking formula. The cause of this kind of signal is unclear but it may be a extremely important clue. We suspect that it may be connected with the underground electromagnetic signal because it doesn't conform to checking formula. 2. The LuDian M6.5 earthquake occurred on August 3, 2014, epicenter was located 26km southwest of LuDian Seismic Station. Except that strain data appeared changes 3 days before the earthquake, the correlation coefficient of surface strain have different values in different stages of earthquake.