Japan Geoscience Union Meeting 2015

Presentation information

International Session (Poster)

Symbol S (Solid Earth Sciences) » S-CG Complex & General

[S-CG15] Detection of microcracks prior to rupture and layered interfaces by the seismoelectronical method

Sun. May 24, 2015 6:15 PM - 7:30 PM Convention Hall (2F)

Convener:*Yukio Fujinawa(Risk Control Associations), Yasuhide Hobara(Graduate School of Information and Engineering Department of Communication Engineering and Informatics, The University of Electro-Communications), Qinghua Huang(Department of Geophysics, Peking University), Niels Grobbe(TU Delft / Delft University of Technology)

6:15 PM - 7:30 PM

[SCG15-P02] Application Prospects of SKZ-1 4-component borehole strain meter

*Xiangyang KONG1, Kaizhi SU2, Yukio FUJINAWA3 (1.Earthquake Administration of Shandong Province,china, 2.Institute of Crustal Dynamics,CEA,china, 3.Risk Control Associations)

Keywords:Borehole strain, Observation technology, Pre-seismic anomaly information

High sensitivity borehole strain meter has good dynamic performance, work stability, anti-interference ability in detecting the regional crustal activity. The structure using four sensing elements that were set at intervals of 45 degree can have a simple "reliability test formula of measurement data" to realize the real-time inspection of data reliability. This method of work has become an important detection means of multi-component borehole strain observation in Mainland China. The structure of the new model introduced by this paper has been confirmed that it can obviously improve the mutual verification result of strain measurement data because the important improvements have been made on displacement transfer structure of underground instrument, and the borehole strain meter has got two pre-seismic anomaly information in experimental observation in ZhaoTong area, YunNan. Now the types of equipment submitted to this conference is expected participants to consider if it can be used in electromagnetic wave observation station network and become an auxiliary observation means that is matching.
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.