# An Analysis of the 2008 \(M_{\rm s}\) 8.0 Wenchuan Earthquake's Aftershock Activity
## 5 Discussion  
The spatial distributions of \(b\)- and \(p\)-values of the aftershock sequence provide useful information for interpreting the rupture mechanisms of earthquakes and understanding the properties of the media in the earthquake area. The spatial variations in these two values may be related to tectonic conditions, rock anisotropy, stress states, surface heat flow, and fault slip in the earthquake area, but no evidence exists to show which factor is the main cause of their variations [19]. [PERSON] et al. [20] investigated the characteristics of the spatial distribution of \(b\)- and \(p\)-values for the aftershock sequence of the Parkfield earthquake. Since then, many studies have been conducted on the spatial distribution of \(b\)- and \(p\)-values, some of which have shown that the spatial variation in the aftershock \(b\)-value is related to stress: a low \(b\)-value after the mainshock indicates that the earthquake area was subjected to high stress [5; 21; 22; 23]. [PERSON] and [PERSON] [2] studied the temporal characteristics of the aftershock sequences of 39 earthquakes in California, USA and did not find a correlation between the \(p\)-value and the \(b\)-value of the aftershock sequences or the magnitude of the mainshock. However, they observed that the \(p\)-value varied from 0.688 to 1.809 and concluded that the \(p\)-value is related to the surface heat flow. [PERSON] and [PERSON] [24] focused on the aftershock sequences of 34 earthquakes in Japan during the 1971-1995 period and concluded that the aftershock parameters of inland earthquakes are mainly affected by the surface heat flow or the anisotropy of the rock structure in the earthquake area. Thereafter, [PERSON] and [PERSON] [13] simultaneously analyzed the spatial variations in the \(b\)- and \(p\)-values for four aftershock sequences of the Kobe, Morgan Hill, Landers, and Northridge earthquakes, and their findings complement the results obtained by [PERSON] and [PERSON] [2] and [PERSON] and [PERSON] [24]. They concluded that although the magnitude-frequency distribution is controlled by shear stress, crack density, and pore pressure, the \(b\)-value is correlated with the amount of fault slip in the mainshock rupture zone, and the \(b\)-value tends to be high in areas with maximum fault slip. [PERSON] and [PERSON] [23] investigated the spatial distributions of \(b\)- and \(p\)-values for the aftershock sequence of the 2000 Western Tottori earthquake. They found that the \(b\)-value was associated with the stress distribution pattern in the earthquake area after the mainshock, whereas the \(p\)-value was related to the amount of fault slip in the mainshock rupture zone, and a large \(p\)-value corresponded to a large amount of fault slip. [PERSON] et al. [25] studied the spatiotemporal rupture process of the Wenchuan earthquake and discovered four areas with concentrated fault slip on the earthquake rupture plane. The largest fault slips were beneath the Wenchuan-Yingxiu area, with a maximum fault slip of 7.3 m, and near the Beichuan area, with a fault slip of 5.6 m. In addition, fault slips were concentrated in the areas of Qingchuan and Kangding, but their scales were smaller than those in the above two areas. Subsequently, [PERSON] et al. [26] analyzed the source process of the Wenchuan earthquake and provided the spatial distribution of fault slip during the mainshock. Their results are consistent with those of [PERSON] et al. [25], but the values differ. We compared the spatial distribution of the calculated \(b\)-value with the abovementioned fault slip distribution and did not find consistency between the two. According to [PERSON] and [PERSON] [13], the \(b\)-value should be large in the region with the largest amount of fault slip, which does not align with our findings. Then, we compared the spatial distribution of the calculated \(p\)-value (Figure 7) with the fault slip distribution and found that the two are correlated.