*Article* **Parallel Computation for Inversion Algorithm of 2D ZTEM**

**Mao Wang 1, Handong Tan 2,\*, Yuzhu Wang 1, Changhong Lin <sup>2</sup> and Miao Peng <sup>2</sup>**


**Abstract:** ZTEM refers to the Z-axis tipper electromagnetic method. The ZTEM method is an airborne magnetotelluric sounding method based on the difference in rocks' resistivity using the native electromagnetic field. The method is effective in exploring large-scale structures when the ground is fluctuant. The paper introduces the inversion algorithm of 2D ZTEM named the conjugate gradient method. This method, which avoids solving the Jacobi matrix, is very effective but not effective enough when the model is divided into a big grid. This study can perform further computation using parallel computation and then receive the processed data. We compare the results of the serial algorithm with the result of the parallel algorithm, which proves that the parallel algorithm is correct. When the number of processes is between three and six, the speedup ratio is between 1.74 and 3.19. It improves the effectiveness of the parallel algorithm of 2D ZTEM.

**Keywords:** ZTEM; 2D forward modeling; inversion; parallel algorithm; tipper
