简介:TheearthresistivityandgeomagneticobservationdataoftheZcomponentfrommanystationsinnear-epicentralareasofstrongearthquakesarecombinedandcalculatedbyusingaspatiallinearitymethodandanewcharacteristicvalue,thespatiallinearitya,describingtheprecursoryfieldinnear-epicentralareaofstrongearthquake,isobtained.Theanalysisandcalculationresultsofgeoelectricandgeomagneticobservationdatapriorto8earthquakeswithM≥5.5occurringintheNorthChinaregionshowthatavalueneartheepicentralareatendstodecreasesignificantlyhalfayearbeforestrongearthquakes.