CAJ | 학술논문

利用面波层析成像和远震接收甬数方法对长白山地区的地壳上地幔速度结构进行了研究.结果表明:长白山火山区附近存在岩石圈减薄、上地幔软流圈增厚以及上地幔S波速度降低等与上地幔高温物质有关的现象,它表明长白山的岩浆系统一直延伸到上地幔软流圈范围.天池火山区地壳内部存在明显的S波低速层,在离天池火山口较近的WQD台附近,低速层顶部埋深约8km,厚度近20km,s波最小速度约2.2km/s.在距离大池火山北部50km的EDO台地壳中没有明显的低速层.火山区S波速度结构总体表现出距离天池越近,地壳的V_P/V_S越大,低速层的厚度和幅度增加的特征,表明天池火山口附近地壳内部存在高温物质或岩浆囊.CBS台站不同方位的接收函数及反演结果表明,地表低速层厚度以及莫霍面深度存在随方位的变化.地表低速层在南部方向明显较厚,莫霍面深度在南部大池火山口方向存在小幅度抬升.CBS台站附近特殊的近地表速度结构可能是该台站记录的火山地震波形主频较低的主要因素.天池火山口附近莫霍面的小幅度抬升意味着存在与火山作用有关的壳幔物质交换通道.
이용면파층석성상화원진접수용수방법대장백산지구적지각상지만속도결구진행료연구.결과표명:장백산화산구부근존재암석권감박、상지만연류권증후이급상지만S파속도강저등여상지만고온물질유관적현상,타표명장백산적암장계통일직연신도상지만연류권범위.천지화산구지각내부존재명현적S파저속층,재리천지화산구교근적WQD태부근,저속층정부매심약8km,후도근20km,s파최소속도약2.2km/s.재거리대지화산북부50km적EDO태지각중몰유명현적저속층.화산구S파속도결구총체표현출거리천지월근,지각적V_P/V_S월대,저속층적후도화폭도증가적특정,표명천지화산구부근지각내부존재고온물질혹암장낭.CBS태참불동방위적접수함수급반연결과표명,지표저속층후도이급막곽면심도존재수방위적변화.지표저속층재남부방향명현교후,막곽면심도재남부대지화산구방향존재소폭도태승.CBS태참부근특수적근지표속도결구가능시해태참기록적화산지진파형주빈교저적주요인소.천지화산구부근막곽면적소폭도태승의미착존재여화산작용유관적각만물질교환통도.
The crustal and upper mantle S-wave velocity structures in Changbaishan volcanic region were obtained from surface wave tomography and teleseismie receiver function modeling. In Changbaishan region, the S-wave velocity shows a thin lithosphere, thick asthenosphere with relatively low S-wave velocity in upper mantle,which indicates the high temperature volcano system at least extends to asthenosphere. There exist distinct low velocity layers in the crust of the volcano area. Beneath WQD station near to the caldera,the low velocity layer at 8km depth is 20km thick with the lowest S-wave velocity about 2.2km/s. Beneath the EDO station located 50km north of Tianchi caldera,no obvious low velocity layer was detected in the crust. The average crustal V_P/V_S near the caldera is higher than those obtained in surrounding area. In the volcanic region, the thickness of crustal low velocity layer is greater and the lowest velocity is more obvious with the distance shorter to the caldera. It indicates the existence of the high temperature material or magma reservoir in the crust near the Tianchi caldera. The receiver functions and inversion result from different back azimuths at CBS permanent seismic station shows that the thickness of near surface low velocity layer and Moho depth change with directions. The near surface low velocity layer is obviously thicker in south direction. The Moho depth shows slightly rising in the direction of the caldera located. We consider that the special near surface velocity structure is the main cause of relatively lower prominent frequency of volcanic earthquake waveform recorded by CBS station. The slightly rising of Moho depth beneath Tianchi caidera indicates there is a material exchanging channel between magma reservoir and upper mantle.