震旦—寒武—奥陶纪
Sinian-Cambrian-Ordovician strata
北川地震纪念馆
beichuan earthquake memorial
大地震震级速报实用化讨论
Quick report for great earthquake magnitude
地面脉冲地震震源
impulsive surface seismic source
地震震害
earthquake damage
Earthquake Damage to Building
earthquake disaster
seismic hazards