10:15 AM - 10:30 AM
[SEM33-06] Temporal Resistivity Change of Crustal Resistivity Structure Before and After the 2011 Tohoku Earthquake
Keywords:resistivity, temporal variation, magnetotellurics, phase tensor, fluid
MT is suitable to detect the fluid migration in the crust, as the resistivity is sensitive to the existence an connectivity of fluids, although they are minor components in the fluid bearing rocks. The previous profile MT dataset over Naruko volcano were obtained in 2003 (Asamori et al., 2010) and we tried to repeat MT measurements at the same places in 2013. Altough we tried to measure at the same spots, the locations are not exactly the same. In particular, we worry about the difference in the near surface local structures of the 2003 and 2013 sites. To overcome this difficulty, we used phase tensor (Caldwell et al, 2004) as response functions, which are insensitive to galvanic distortions of the near-surface local structure. To evaluate the temporal changes, it is important to show the errors of the phase tensors. For this, we used boot-strap method with 1000 realizations. We compiled the difference of α, β, φmax, φmin with error bars for all the period range. We found some consistent differences in the phase tensor parameters.