It remains elusive why there was only weak and limited ground shaking in Kathmandu valley during the 25 April 2015 Mw 7.8 Gorkha, Nepal, earthquake. Our spectral element numerical simulations show that, during this earthquake, surface topography restricted the propagation of seismic energy into the valley. The mountains diverted the incoming seismic wave mostly to the eastern and western margins of the valley. As a result, we find de-amplification of peak ground displacement in most of the valley interior. Modeling of alternative earthquake scenarios of the same magnitude occurring at different locations shows that these will affect the Kathmandu valley much more strongly, up to 2-3 times more, than the 2015 Gorkha earthquake did. This indicates that surface topography contributed to the reduced seismic shaking for this specific earthquake and lessened the earthquake impact within the valley.

中文翻译：

---

2015年尼泊尔廓尔喀地震期间地表地形对加德满都谷地弱震动的影响


2015 年 4 月 25 日尼泊尔廓尔喀 7.8 级地震期间，加德满都谷地为何只发生微弱且有限的地面震动，目前仍不清楚。我们的谱元数值模拟表明，在这次地震中，地表地形限制了地震能量向山谷的传播。山脉将传入的地震波大部分转移到山谷的东部和西部边缘。结果，我们发现山谷内部大部分地区的峰值地面位移不再放大。对不同地点发生的相同震级的替代地震情景进行的建模表明，这些地震对加德满都谷地的影响将比 2015 年廓尔喀地震严重得多，最多可达 2-3 倍。这表明地表地形有助于减少这次特定地震的地震震动，并减轻了山谷内的地震影响。