As part of a broader effort to develop ground‐motion data resources for China in a manner consistent with Next Generation Attenuation projects, we develop a database of geotechnical soil profiles and shear‐wave velocity (⁠ $VS$⁠) logs for sites having ground‐motion accelerometers (this database is referred to as soil profile database [SPD]), and then use that data to develop site parameters. The site information is compiled for stations within the National Strong Motion Observation Network System (NSMONS) of China. This effort is focused on four provinces in western China (Yunnan, Sichuan, Gansu, and Xinjiang), which contribute 871 of 2023 NSMONS stations throughout China. Of the 871 sites, the SPD provides site information for 678 sites, or 78% of the total. To develop the SPD, geotechnical logs and/or $VS$ profiles are compiled for 637 sites. This information is derived from previously unpublished reports and is assembled here in a uniform format and partially disseminated (only approximate site locations are provided). The remaining 41 sites in the SPD have confirmed bedrock conditions at the ground surface. Site metadata and parameters are compiled into a database, included as a supplemental material to this article, that includes the depth to the first occurrence of 0.5 km/s shear‐wave velocity (⁠ $Z0.5$⁠), three time‐averaged shear‐wave velocity parameters (⁠ $VSe$⁠, $VS20$⁠, $VS30$⁠), and site classifications based on the Chinese building seismic design code and National Earthquake Hazards Reduction Program Provisions. For sites with $VS$ profiles that do not extend to 30 m, we present region‐specific recommendations for extrapolating time‐averaged velocities from the profile depth to 30 m. For sites with geotechnical logs but no profiles, we present procedures to estimate $VS$ profiles from which the earlier parameters can be derived.

The time‐evolving growth behavior during the early phase of an earthquake rupture and when distinguishable features arise for events of different sizes are critical issues for real‐time seismology. These issues are related to the key concept of rupture predictability, which directly determines the warning time and the potential of earthquake early warning systems. P waves carry the temporal information of rupture development, which provides us with an important clue to investigate and understand the source physical process in the early stage of the rupture. In this article, for 36 shallow, moderate‐ to large‐magnitude earthquakes (⁠ $5.0≤Mw≤9.1$⁠) that occurred in Japan and China, we systematically assess and quantify the temporal evolution of the P‐wave velocity amplitude (V‐env) and the characteristic period (⁠ $τc$⁠). The initial growth rate and the secondary evolution parameters are extracted to investigate the main features of the early rupture behavior. Our results show that the V‐env exhibits distinguishable growth features after a similar steep rise affected by propagation attenuation for earthquakes of different sizes. Near the distinguishable points, the bell‐shaped fluctuations are generally observed in the $τc$ curves, and the fluctuation amplitude is positively correlated with the final magnitude. The distinct evolution of P waves radiated from earthquakes of different magnitudes occurs earlier than one‐half of the rupture duration, which constitutes new evidence supporting the weak predictability of ruptures. Finally, we discuss the implications for the physical source mechanism and earthquake early warning.