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?????б????α????????SWW??2.8 km??????????????α???????????α????????????21???25??????????????????????????????????????????????1995??2001???????4??Ms??6.0????????????????????????????????????W????????????????????????????°???????????????????1.00?????9 mm?????????????????4??6???￡????о??140 km?????????????????????????????ж??????????

MULTIPLE REAPPEARANCE OF EARTHQUAKE PRECURSOR ANOMALIES MEASURED BY YONGSHENG FIXED-POINT DEFORMATION MEANS

The observations for 21 and 25 years have been accumulated respectively at Yongsheng tilt tide deformation station and the vertical deformation station across Chenghai fault,which is 2.8 km apart from Yongsheng station in SWW direction. After processing these data by use of a variety of methods for recognizing and extracting the abnormal information, it is found that there had been reappearances of abnormal information of Ms≥6.0 strong earthquakes 4 times during 1995-2001. Their patterns are “left steep and right gentle (W tilt as stair) type”, “down peak reflex type”, “symmetrical concave downward type” respectively; the magnitudes are≥1.00 and ≥9 mm respectively; the time: the latter is 4-6 months earlier than the former; the epicentral distances are ≤140 km.Thus we drew up the guides to the medium short term prediction at above two sensitive points for monitoring strong earthquakes.