以首都圈地震预警原型系统为例，讨论了地震早期预警系统（EEWS）设计中如何通过对"盲区"的控制达到最大限度减轻地震灾害损失的目的，认为如果不仅考虑走时，而且考虑有限震源尺度和记录台站的实际工作状况，那么在台间距为20km时继续加密台站，虽不再能明显减小"盲区"，却仍可以对控制"盲区"、提高预警系统的减灾效能发挥重要作用。

Controlling the ‘blind zone’ of an Earthquake Early Warning System(EEWS),that is,to avoid the unexpected/accidental expansion of the ‘theoretical blind zone’ in the real operation of the EEWS,is one of the key issues in the design and implementation of the system. Taking the prototype EEWS of the Beijing Capital Circle region as an example,we analyzed the control of the EEWS ‘blind zone’ for minimizing earthquake disasters. It is pointed out that,if not only travel times but also the finite size of seismic sources,and the failure of seismic stations are taken into account,increasing the density of seismic stations with inter-station distances less than 20km is still useful for controlling the ‘blind zone’. Decreasing the inter-station distance below 20km,although having minor contribution to reducing the size of the ‘blind zone’,plays an important role in significantly improving the performance of the EEWS.

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