TY - JOUR

T1 - Multidimensional interpretation of radiomagnetotellurics and controlled-source radiomagnetotellurics data: A validation study

AU - Asghari, Shiva Fadavi

AU - Шлыков, Арсений Андреевич

AU - Smirnova, Maria

AU - Сараев, Александр Карпович

AU - Yogeshwar, Pritam

AU - Tezkan, Bülent

PY - 2023/8/1

Y1 - 2023/8/1

N2 - Radiomagnetotellurics (RMT) is an electromagnetic method that uses signalsfrom radio transmitters broadcasting in the 10 kHz to 1 MHz frequency range.Due to its limited frequency range, RMT is commonly used as a shallow-depthinvestigation tool. However, in remote areas, there is a lack of radio transmittersand only signals from very low frequency (VLF) antennas (10–30 kHz frequencyrange) can be measured. This can give rise to low signal-to-noise ratio. To overcome this disadvantage of RMT, a controlled-source RMT (CSRMT) can beapplied to measure signals of the low-frequency (LF) and mid-frequency ranges(30–1000 kHz). Moreover, the wider frequency range of the CSRMT method(down to 1 kHz) leads to a deeper sounding depth.We present the first RMT andCSRMT validation studies using two perpendicularly located horizontal electricdipoles to realize a 3D inversion of CSRMT data.The survey area in Alexandrovavillage in Kaluga region, Russia, a previously investigated area, was selectedfor a validation study. We acquired the data along 8 profiles with 175 stations.Transmitter lines for the CSRMT case were about 900 m long, and the minimumand maximum distances of the stations from transmitters were 450–1000 m,respectively.We applied 2D and 3D inversions over the far-field data and compared with the previous results. The available geophysical information as well as the borehole data indicate a high agreement between the obtained models and the geological structure.We can confirm that the CSRMT method is a reliable approach for near-surface explorations and that, the existing advanced and tested inversion tools for magnetotellurics, can be used to invert the RMT and far-field zone CSRMT data leading to comparable results.

AB - Radiomagnetotellurics (RMT) is an electromagnetic method that uses signalsfrom radio transmitters broadcasting in the 10 kHz to 1 MHz frequency range.Due to its limited frequency range, RMT is commonly used as a shallow-depthinvestigation tool. However, in remote areas, there is a lack of radio transmittersand only signals from very low frequency (VLF) antennas (10–30 kHz frequencyrange) can be measured. This can give rise to low signal-to-noise ratio. To overcome this disadvantage of RMT, a controlled-source RMT (CSRMT) can beapplied to measure signals of the low-frequency (LF) and mid-frequency ranges(30–1000 kHz). Moreover, the wider frequency range of the CSRMT method(down to 1 kHz) leads to a deeper sounding depth.We present the first RMT andCSRMT validation studies using two perpendicularly located horizontal electricdipoles to realize a 3D inversion of CSRMT data.The survey area in Alexandrovavillage in Kaluga region, Russia, a previously investigated area, was selectedfor a validation study. We acquired the data along 8 profiles with 175 stations.Transmitter lines for the CSRMT case were about 900 m long, and the minimumand maximum distances of the stations from transmitters were 450–1000 m,respectively.We applied 2D and 3D inversions over the far-field data and compared with the previous results. The available geophysical information as well as the borehole data indicate a high agreement between the obtained models and the geological structure.We can confirm that the CSRMT method is a reliable approach for near-surface explorations and that, the existing advanced and tested inversion tools for magnetotellurics, can be used to invert the RMT and far-field zone CSRMT data leading to comparable results.

KW - 3D

KW - electromagnetic

KW - frequency

KW - inversion

KW - shallow subsurface

UR - https://onlinelibrary.wiley.com/doi/full/10.1002/nsg.12257

UR - https://www.mendeley.com/catalogue/2fc803e6-1a04-3ff8-af93-95fa8ce60e01/

U2 - 10.1002/nsg.12257

DO - 10.1002/nsg.12257

M3 - Article

VL - 21

SP - 300

EP - 313

JO - Near Surface Geophysics

JF - Near Surface Geophysics

SN - 1569-4445

IS - 4

ER -