本文關(guān)鍵詞： 余震 滑動(dòng)位移 非均勻應(yīng)力變化 圓盤模型　出處：《地球物理學(xué)報(bào)》2016年06期 　論文類型：期刊論文

【摘要】：本文利用2015年尼泊爾MW7.9地震斷層面滑動(dòng)位移分布的運(yùn)動(dòng)學(xué)反演結(jié)果,通過傅里葉變換法得到了主斷層面上的兩分量應(yīng)力狀態(tài),并研究了余震的空間分布和斷層面上應(yīng)力狀態(tài)之間的關(guān)系.發(fā)現(xiàn)滑動(dòng)位移分布與應(yīng)力狀態(tài)分布都相對(duì)較為集中,大約70%的余震分布在應(yīng)力變化為正的區(qū)域,而其余發(fā)生在應(yīng)力降區(qū)域的余震,又大多發(fā)生在應(yīng)力變化梯度較大的地區(qū).為了得到一個(gè)更符合實(shí)際的滑動(dòng)模型來解釋余震的觸發(fā)機(jī)制,我們計(jì)算了波數(shù)域中滑動(dòng)位移和應(yīng)力狀態(tài)的傅里葉譜,發(fā)現(xiàn)此次地震的滑動(dòng)位移和應(yīng)力狀態(tài)近似滿足k-3和k-2衰減.我們利用簡(jiǎn)化的圓盤模型說明了非均勻應(yīng)力變化下的衰減過程,計(jì)算了圓盤模型的有效半徑re約等于0.7倍的圓盤半徑.這就說明圓盤模型中應(yīng)力增加的部分應(yīng)該占整個(gè)圓盤破裂面積的51%.在本次尼泊爾MW7.9地震實(shí)例中,斷層面上應(yīng)力狀態(tài)為負(fù)的區(qū)域比滑動(dòng)位移為正的區(qū)域有了明顯地縮小.事實(shí)表明,余震可以發(fā)生在有滑動(dòng)位移的區(qū)域,非均勻應(yīng)力降模型比均勻應(yīng)力降模型更加接近真實(shí)的震源破裂過程.
[Abstract]:Based on the kinematic inversion results of the slip displacement distribution on the fault plane of the MW7.9 earthquake in Nepal on 2015, the two-component stress state on the main fault plane is obtained by Fourier transform method. The relationship between the spatial distribution of aftershocks and the stress state on the fault plane is studied. It is found that the distribution of sliding displacement and stress state are relatively concentrated, and about 70% of the aftershocks are distributed in the region where the stress change is positive. In order to obtain a more realistic sliding model to explain the trigger mechanism of aftershocks, most of the remaining aftershocks occurred in the regions with large stress gradient. The Fourier spectra of sliding displacement and stress state in wavenumber domain are calculated. It is found that the sliding displacement and stress state of the earthquake approximately satisfy the k-3 and k-2 attenuation. We use the simplified disk model to illustrate the attenuation process under the inhomogeneous stress variation. The effective radius re of the disc model is calculated to be about 0.7 times the radius of the disk. This means that the stress increase in the disc model should account for 51% of the whole disc rupture area. In this case, the Nepal MW7.9. In an earthquake. The region with negative stress state on fault plane is obviously smaller than that with positive sliding displacement. The facts show that aftershocks can occur in areas with sliding displacement. The nonuniform stress drop model is closer to the real source rupture process than the uniform stress drop model.
【作者單位】： 中國(guó)地震局地殼應(yīng)力研究所(地殼動(dòng)力學(xué)重點(diǎn)實(shí)驗(yàn)室);中國(guó)科學(xué)院大學(xué)地球科學(xué)學(xué)院;
【基金】：中國(guó)地震局地殼應(yīng)力研究所中央級(jí)公益性科研院所基本科研業(yè)務(wù)專項(xiàng)(ZDJ2013-13) 國(guó)家青年科學(xué)基金項(xiàng)目(41404044) 中國(guó)地震局尼泊爾地震科考項(xiàng)目共同資助
【分類號(hào)】：P315
【正文快照】： 1引言北京時(shí)間2015年4月25日14點(diǎn)11分26秒,臨近我國(guó)西藏自治區(qū)的尼泊爾境內(nèi)發(fā)生了MW7.9強(qiáng)烈地震.UGSG測(cè)定震源位置為28.147°N,84.708°E,震源深度15km.震中位于尼泊爾博克拉市,距離首都加德滿都西北77km處,是自1950年MW8.7察隅地震以后尼泊爾近70年來受到影響最大的地震(Mitt

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