5:15 PM - 7:15 PM
[STT39-P03] Relationship between Resistivity obtained by Airborne Electromagnetic Method (P-THEM) and Geology
Keywords:Airborne Electromagnetic Survey, Airborne magnetic survey, Resistivity, Magnetic intensity
Airborne electromagnetic surveys using the P-THEM system (Time-domain Airborne Electromagnetic survey, Airborne Magnetic Survey, simultaneous measurement) have been used in many locations throughout Japan. Airborne electromagnetic surveys can determine three-dimensional resistivity distributions, while airborne magnetic surveys can determine two-dimensional magnetic anomalies. Magnetic surveys can also determine three-dimensional magnetization intensity distributions through inverse analysis.
Airborne electromagnetic surveys transmit electromagnetic waves from the ground or airborne platform and measure induced magnetic fields underground without grounding. However, the measurement area differ due to variation in the measurement principle and methods. For this reason, the absolute values do not necessarily match to the results measured from the ground based surveys, such as ground electrical surveys, and the order of magnitude may differ by one or two digits. Even with the same airborne electromagnetic survey, there is tendency for absolute values to vary depending on the measurement method.
Due to this situation, the relationship between resistivity values obtained by airborne electromagnetic surveys and geology cannot be explained by the geological indices published by the Society of Exploration Geophysics and other organizations. Magnetic survey indicators typically use the magnetic susceptibility of rocks for comparison, but there is no published materials comparing the relationship between magnetic intensity and geology. For this reason, we will compare the relationship between the resistivity, magnetic intensity values and the geology that we have accumulated so far and use them as indicators for our analysis. The geology of the surveyed areas does not cover the representative geology of Japan, and the number of data quantity is limited, so the findings are not satisfactory, but it is expected that it will be useful for interpreting the geological features of future airborne electromagnetic surveys.
Airborne electromagnetic surveys transmit electromagnetic waves from the ground or airborne platform and measure induced magnetic fields underground without grounding. However, the measurement area differ due to variation in the measurement principle and methods. For this reason, the absolute values do not necessarily match to the results measured from the ground based surveys, such as ground electrical surveys, and the order of magnitude may differ by one or two digits. Even with the same airborne electromagnetic survey, there is tendency for absolute values to vary depending on the measurement method.
Due to this situation, the relationship between resistivity values obtained by airborne electromagnetic surveys and geology cannot be explained by the geological indices published by the Society of Exploration Geophysics and other organizations. Magnetic survey indicators typically use the magnetic susceptibility of rocks for comparison, but there is no published materials comparing the relationship between magnetic intensity and geology. For this reason, we will compare the relationship between the resistivity, magnetic intensity values and the geology that we have accumulated so far and use them as indicators for our analysis. The geology of the surveyed areas does not cover the representative geology of Japan, and the number of data quantity is limited, so the findings are not satisfactory, but it is expected that it will be useful for interpreting the geological features of future airborne electromagnetic surveys.