[1]LIU Zifeng,ZHANG Tianji,FU Hong,et al.Characteristics of Wave Velocity Ratio Change before Yunnan Tonghai MS5.0 Earthquake in 2018[J].Journal of Seismological Research,2018,41(04):494-502.
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Characteristics of Wave Velocity Ratio Change before Yunnan Tonghai MS5.0 Earthquake in 2018
Journal of Seismological Research[ISSN 1000-0666/CN 53-1062/P] Volume:
41
Number of periods:
2018 04
Page number:
494-502
Column:
Public date:
2018-10-20
- Title:
- Characteristics of Wave Velocity Ratio Change before Yunnan Tonghai MS5.0 Earthquake in 2018
- Keywords:
- the Tonghai MS5.0 earthquake; wave velocity ratio; Wadati method of single station and multi-earthquake; Yunnan
- CLC:
- P315.727
- DOI:
- -
- Abstract:
- Based on the phase arrival time data of the ML≥2.0 earthquakes recorded by Yunnan Digital Seismic Network from Jan.1,2011 to Jul.31,2018,we calculated the wave velocity ratios of 51 stations by using the Wadati method of single station and multi-earthquake,and analyzed the temporal and spatial evolution characteristics of wave velocity ratios before the Tonghai MS5.0 earthquake on Aug.13 and Aug.14 in 2018.The results show that:(1)Before the Tonghai earthquake,the mian characteristic of the wave velocity ratio near the epicenter shows high value changes.The wave velocity ratio of four stations experienced the process of decline-recovery in a long period before the high value.(2)There is a certain relationship between the occurrence time of wave velocity change and epicentral distance.The time of wave velocity ratio begins to decline,rise and reach high value of the Tonghai Station which is closer to the epicenter is later than that of Jianshui,Yuanjiang and Gejiu Stations which are farther from the epicenter.(3)The epicenters of the four MS≥5.0 earthquakes in Yunnan from 2015 to 2017 located at the area of decreasing or the positive and negative changes of wave velocity ratio in one year before the earthquake.And the location of epicenter of Tonghai earthquake follows the same law,which is the intersection zone of increasing and decreasing wave velocity ratio from Jan.to Jul.in 2018.The preliminary analysis suggests that the increasing of the wave velocity ratio before the earthquake may be due to the fluid infiltration around the epicenter during the late stage of the seismogenic process.The participation of fluid makes the micro-crack caused by stress enhancement in the early stage reaches the state of water saturation,resulting in the wave velocity ratio vP〖JB<1/〗vS increased.
- References:
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Last Update:
2018-10-30