9:30 AM - 9:45 AM
[SEM12-03] Electrical conductivities of Kanto region estimated from P-wave velocity data
Keywords:conductivity, P wave velocity, porosity
Information of a conductivity distribution of Kanto region is limited because of severe urban noise. However, there is a demand for it in order to estimate Geomagnetically Induced Currents there precisely.
In this study, we attempt to estimate a conductivity distribution of the region. For the upper crust and a part of the lower crust, data sets of the seismic P-wave velocity distribution in Kanto region were converted to a conductivity distribution. The conductivity and the P-wave velocity are both related to the porosity, therefore, it is theoretically possible that the conductivity can be estimated from the P-wave velocity via the porosity, However, the relationship between the conductivity and the P-wave velocity depends on conditions of rocks and several conversion formulae are proposed. We tested several formulae based on Corcione et al. (2007). In addition, we found that the temperature can play a role to estimate the conductivity of the upper crust. The temperature dependency of rock properties were read from a laboratory measurement by Yokoyama (1983).
Forward modeling of the geoelectric field in Kanto region was conducted by using the estimated conductivity distribution. A comparison between observed and computed geoelectric fields at Kakioka suggests that an larger amplitude of the eastward component of the geoelectric field at Kakioka might not be reproduced by a complicated conductivity distribution around Kakioka.
In this study, we attempt to estimate a conductivity distribution of the region. For the upper crust and a part of the lower crust, data sets of the seismic P-wave velocity distribution in Kanto region were converted to a conductivity distribution. The conductivity and the P-wave velocity are both related to the porosity, therefore, it is theoretically possible that the conductivity can be estimated from the P-wave velocity via the porosity, However, the relationship between the conductivity and the P-wave velocity depends on conditions of rocks and several conversion formulae are proposed. We tested several formulae based on Corcione et al. (2007). In addition, we found that the temperature can play a role to estimate the conductivity of the upper crust. The temperature dependency of rock properties were read from a laboratory measurement by Yokoyama (1983).
Forward modeling of the geoelectric field in Kanto region was conducted by using the estimated conductivity distribution. A comparison between observed and computed geoelectric fields at Kakioka suggests that an larger amplitude of the eastward component of the geoelectric field at Kakioka might not be reproduced by a complicated conductivity distribution around Kakioka.