Based on the compiled aeromagnetic data and Bouguer gravity data, the study used 2D forward modeling and 3D inversion method to create a more detailed and visible magnetic and density model beneath the Longmenshan Fault Zone. There are plenty of seismic studies in this region, but aeromagnetic and Bouguer gravity studies are rare, therefore this study has its value to further understand the tectonic background of the Wenchuan and Lushan earthquakes. I recommend to be published with minor revisions listed below.

Minor Questions:

• Line 83: “Triassic syntectonic adakitic-type granitoids are widely distributed in the SGB, which are likely sourced from the partial melting of an underlying Proterozoic basement that is part of the Sichuan Basin”. The Sichuan basement may extend further west beyond the LFZ, but I don’t think it can account for the “syntectonic adakitic-type granitoids”far west from the LFZ.

• Figure 1: add descriptions for the black lines (profiles? ), pink squares (measurement points?)  to the captions.
• Figure 2b, 3a, 3b actually show that the anomaly across F6 (Longquan fault) are different. On Figure 3b, the values are positive (>3) and negative (<-7) to the west and east of the F6.  On figure 4, the F6 is also a feature to separate low/high gravity. These observations are contrary to your interpretation on Line 225 that the F6 is a shallow fault.    
• Theobvious magnetic discontinuous distributed from Daofu and Danba to Chengdu is interpreted as a concealed fault. If look at the Figure 3, the trace of this discontinuity may actually continue to the south of Nanchong. There are other discontinuities too, but only this one is interpreted as a concealed fault? This feature doesn’t show up on the gravity map (Figure 4).  do you have other evidences to support your interpretation?
• Figure 4a, please add numbers to the color scale; Figure 4a and 4b, the blue boxes are seismic gap? Please describe in the caption.
• Line 345: “Two earthquakes lie in high magnetic areas from 20 to 40 km”.The depths of the two earthquakes are less than 20km. This statement could be misleading. 
• Figure 11, the HMB2 could be the Leshan-Longnvshi uplift as mentioned by Liu et al. (2021, Earth Science Review, title: Tectonic evolution of the Sichuan Basin, Southwest China).
• The paper outlines three models on Lines54-57, then what’s the difference between your model and the other three models? More specifically, what’s the difference between your model and Liang et al. (2018)?