Estimation of Depth and Attenuation of Earthquakes in Bolivia
Estimation of Depth and Attenuation of Earthquakes in Bolivia
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玻利维亚地震深度和衰减的估计
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发表时间：
2000
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通讯作者：
L. Drake
中科院分区：
文献类型：
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作者：
L. Drake
众所周知，如果没有深度相位或附近几个地震台的相位，许多地震的深度就不能准确确定，必须进行赋值。在俯冲带尤其如此。仔细绘制了玻利维亚11个有感地震的烈度图，并根据Kövesligethy公式I 0- In = a log（rn/h）+ B（rn-h）确定了这些地震的深度，其中rn是到最接近烈度In点的平均震源距离，h是深度，a和B是常数，In小于I 0。在确定了地震深度后，得到了地震引起的水平加速度的近似值：log ah = 0.35 Mw - 0.54 log（r/h）- 0.0036（r/h），h < 70 km log ah = 0.33 Mw - 1.38 log（r/h），70 km <= h < 150 km log ah = 0.30 Mw - 1.50 log（r/h），150 km <= h < 330 km log ah = 0.21 Mw - 1.85 log（r/h），330 km <= h其中r是震源距离，Mw是矩震级。与Richter（1958）和Veith和Clawson（1972）的P波衰减以及Campillo和Plantet（1991）的France的Pg和Lg波衰减进行了比较。随着玻利维亚中部科恰班巴周围地震台阵的运作，玻利维亚的地震事件定位和衰减观测有了很大改进。
It is well known that, without depth phases or phases from a few nearby seismograph stations, the depths of many events cannot be accurately determined and must be assigned. This is especially true in regions of subduction. Carefully drawn intensity maps of 11 felt earthquakes in Bolivia have been examined and the depths of these earthquakes have been determined from the Kövesligethy formula I0 – In = a log (rn/h) + b(rn – h) where rn is the mean hypocentral distance to the closest points of intensity In, h is depth, a and b are constants and In is less than I0. With the depths of the earthquakes determined, the approximate horizontal acceleration caused by them has been found to be log ah = 0.35 Mw – 0.54 log (r/h) – 0.0036 (r – h), h < 70 km log ah = 0.33 Mw – 1.38 log (r/h), 70 km <= h < 150 km log ah = 0.30 Mw – 1.50 log (r/h), 150 km <= h < 330 km log ah = 0.21 Mw – 1.85 log (r/h), 330 km <= h where r is hypocentral distance and Mw is moment magnitude. The attenuation corresponding to these accelerations has been compared with that for P waves of Richter (1958) and of Veith and Clawson (1972), and with that for Pg and Lg waves for France of Campillo and Plantet (1991). With the seismic array around Cochabamba in central Bolivia operating, locations of seismic events and observations of attenuation in Bolivia have been much improved.