Details of the Abstract
| Title of paper | An application of rotational impedance to handle galvanic distortion in USArray data |
| List of authors | Tawat Rung-Arunwan, Hisashi Utada |
| Affiliation(s) | Independent consultant, Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan |
| Summary |
A number of inversion approaches to handle distorted MT dataset have been developed. One practical solution to invert the distorted data is the phase tensor inversion using the SSQ1D model, the 1-D resistivity model derived from average SSQ impedance. Using the SSQ1D model as an initial or prior model is the key to obtain the stable and reliable results. This work aims to examine this scheme on the real data using the USArray data. For this purpose, we chose two array datasets over the State of Nebraska and Iowa. As indicated by the local distortion indicator, the sub-array over the State of Nebraska are weakly distorted, while that over the State of Iowa strongly distorted. When the given MT dataset is weakly distorted, inverting the phase tensor provides 3-D model with relatively small variance at the near surface, which suggests less heterogeneities. However, when the dataset is severely distorted, inverting the phase tensor produces the near-surface heterogeneous layer. We then investigate inverting the phase tensor and the ssq impedance with the gain correction, which is made by dividing the ssq impedance with the apparent gain. The results suggest that this approach could be another promising option. The inverted model shows less variation at the shallow part for the strongly distorted dataset, while the main feature are similar among the inverted models derived from different data combination. |
| Session Keyword | 2.0 EM theory, modelling and Inversion |
| File upload |
2.0_an_application_of_rotatio_rung-arunwan_01.pdf
|