简介:Intheestimationofseismictendency,usingGutenberg-Richter¢sb-valueandusingHurstexponentaretwocom-monlyusedmethods.Basedonthefractalgeometryofearthquaketimeseries,wepointoutthatthesetwomethodscorrelatetoeachother.IntheperspectiveoffractionalBrownianmotion(FBM),anearthquakesequencewithb>3/4andthatwithb<3/4havedifferentdynamicproperties.
简介:WeusedearthquakecatalogsrecordedbyGuangdongSeismologicalNetworkfrom2008to2014toresolvethespatialvariationsofb-valuesinthecoastalareaofGuangdong,particularlyinthreekeyresearchareas(Yangjiang,Heyuan,andoffshoreNanaoIsland)withstrongseismicity.Ourresultsrevealedthatb-valuesexhibitedsignificantspatialvariations,andzoneswithlowb-valuescouldindicatethemostlikelyseismogenicareaoflargeearthquakes.Weobservedthreeclearlowb-valuepatchesintheoffshoreNanaoIsland.Wefoundadistincthighb-valuepeakatthedepthof11kmandtwominimumpeaksatabout14and7–8kmintheYangjiangarea.Theoverallb-valuesgenerallydecreasewithdepthintheHeyuanarea.Thespatialvariationsofb-valuesreflecttectonicanomalies;thatis,the‘low-high-low’distributionofb-valuesintheoffshoreNanaoIslandandtheYangjiangareamayindicatetheanomalyofthecrustalstructurewithaweaklayer.Theb-valuesofreservoir-inducedseismicityareobviouslylowerthanthatinducedbytectonism.Thisfindingindicatesthatthereservoirareaisgenerallyathighstressstateundertheconditionofhighporepressure.Weinferredthatlargeearthquakesmightbepronetooccurat10–12kmdepthintheoffshoreNanaoIsland,at12–15kmdepthintheYangjiangarea,andatthelowerpartoftheseismicactivityzoneintheHeyuanarea.Moreover,theupstreamareaoftheXinfengjiangreservoiristhemostlikelyareaoffuturelargeearthquakesintheHeyuanarea.
简介:摘要: 随着我国经济在快速发展,社会在不断进步,桥梁建设在我国不断增多, 在桥梁实际运营中,会发现一些桥梁两侧伸缩缝间距相差较大,为弄清产生此种情况的原因,对桥梁进行位移监测至关重要,本文以天保立交桥为依托,通过结构位移监测系统,并辅以人工现场测量相印证的方式对结构位移变化状况进行监测,得出的主要结论为:①天保立交桥上部结构的人工测量伸缩最大值在 ±2cm 左右,与监测系统监测的支座处梁体位移极值( 21.3mm )基本吻合,拉线位移计的纵向位移量基本是由梁体自身变形引起的,结构纵向基本没有滑移现象;② 5# 墩支座处的横向位移值很小,最大位移值不超过 1mm ,结构横向状态稳定。