摘要
In 2004, China's National Digital Network of Earthquake Observation planned todeploy 40 YRY-4 Four Component Strainmeter. Clear strain anomaly before 2008. 5.12 was ob-served at YRY-4 strain stations close to Wenchuan. Another anomaly occurred before the LihuiML 6.1 earthquake on Aug.30,2008 and a prediction of the quake made by this anomaly was suc-cessful. Thus it is very important to speed up a nation wide dense network of strain observation.