The influence of the source parameters on M_s is studied through numerical simulations based on finite-fault models. The results show that the M_s is negatively correlated with earthquake rupture duration when moment magnitude remains unchanged. The source parameters that can impact the rupture duration contain the sub-fault duration, rupture velocity, and rupture length. Among them, the sub-fault duration and rupture length is negatively correlated with M_s, while the rupture velocity is positively correlated with M_s, if the moment magnitude remains unchanged. The fact that the measured M_s of strong earthquakes in the mainland of China are significantly larger than moment magnitudes may be due to two reasons. First, the strong earthquakes in the mainland of China are mostly intraplate earthquakes with relatively higher stress drop values, which may have short rupture duration and rupture length. Secondly, M_s determined by China Earthquake Networks Center (CENC) is systematically larger than M_s(20) determined by National Earthquake Information Center.

基于有限断层模型和数值模拟, 研究震源参数对面波震级的影响。结果表明, 在矩震级相同的情况下, 地震破裂持续的时间越短, 面波震级就越高, 反之亦然。影响地震持续时间的震源参数包括子断层破裂持续时间、破裂速度和破裂长度。若地震矩不变, 子断层破裂持续时间和破裂长度与面波震级负相关, 破裂速度与面波震级正相关。中国大陆测定的面波震级多数情况下显著高于矩震级的原因可能有二: 一是中国大陆发生的强震多为板内地震, 由于应力降偏大, 破裂持续时间和断层长度可能偏短; 二是相对于美国国家地震信息中心测定的M_s(20), 中国地震台网中心测定的面波震级系统性地偏大。