Apply iTilt-Euler method on the magnetic anomaly at southwest of Penghu.

By checking the magnetic data measured from New Ocean Reacher 3 at 2020/9/21 to 29, we can easily find that there are two anomalies localized south-west of Penghu. In the west, it is located around 119.08°E, 23.46°N and with defect amount 620 nT. The other site is located at 119.34°E, 23.45°N but not as solid as the first one (340 nT).

To understand the magnetic structure below these two sites, this study will use the iTilt-Euler method as the primary method for calculating the depth of these two magnetic anomalies. Before applying iTilt-Euler method, I’ll calculate total horizontal gradient and only use “quality of local maximum” larger than 3 to make sure the input data are around the edge of the source. Following the iTilt-Euler method, we will use the zero-order analytical signal as a constraint to select solutions that are above the structure. Finally, we will use the average of the selected solutions representing the properties of this anomalous site.

After going through the whole process, we discovered that the structure of the western site could be the fault with the top 0.88 km depth and the mean structural index 0.23. And the other site could be the dike, which is 1.8 km depth and has an average structural index of 1.4.