Weselectedthe103ML≥2.5earthquakewaveformdatafromtheInnerMongolia-Ningxiaborderduring2009-2015,whichwasrecordedbytheInnerMongoliaDigitalSeismicNetworksandusedthesimplexmethod,Hyposatmethod,doubledifferencelocationmethod,anddeterministicmethod(PTD)forthedeterminationoffocaldepth,andcomparedtheresults.TheCAPmomenttensorinversionmethodisusedtodeterminethefocaldepthsoftheAlxaLeftBannerM5.8andM4.2earthquakes.Thefinalresultsofthefocaldepthbythedeterministicmethod(PTD)andthedoubledifferencelocationmethodfitwellwiththetectoniccharacteristicsoftheInnerMongolia-Ningxiaborderarea,butthoseofthesimplexmethodandtheHyposatmethoddonot.TheaveragedepthoftheInnerMongolia-Ningxiaborderseismictectoniczoneis13.32±8km.
