Dispersion of very long‐period rayleigh waves along the East Pacific Rise: Evidence for S wave velocity anomalies to 450 km depth
Dispersion of very long‐period rayleigh waves along the East Pacific Rise: Evidence for S wave velocity anomalies to 450 km depth
复制标题
沿东太平洋海隆的极长周期瑞利波的色散：450公里深度的S波速度异常的证据
DOI：
10.1029/jb087ib10p08631
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发表时间：
1982
影响因子：
--
通讯作者：
L. Knopoff
中科院分区：
文献类型：
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作者：
E. Wielandt;L. Knopoff
第二次加兹利地震的基模瑞利波的相位频散已经在洛杉矶和南极之间的40到400秒之间进行了测量。在它的大部分长度上，两个站点之间的路径是平行的，靠近东太平洋隆起。我们观测到的相速度明显低于全球平均水平。海洋的反转路径的一部分给横波速度模型(1)异常低速度深度约200公里,最低为4.1 km / s 100公里左右,(2)正常或略低于正常速度之间200公里和400公里深处,和(3)萧条olivine-spinel阶段的边界约50公里,或同等速度减少约450公里的深度没有地幔不连续的模型。对于地幔中更深的异常，我们不能作出明确的断言。200 km以下的速度异常与1066B模式中671 km处低速带和尖晶石过渡带之间的上地幔温度相对于地球平均温度升高140°K的假设相一致。提出了对习惯数据处理程序的修正，旨在消除在大于240秒的周期内估计离散度时的偏差。
The phase dispersion of fundamental-mode Rayleigh waves from the second Gazli earthquake has been measured at periods between 40 and 400 s between Los Angeles and the South Pole. Over most of its length, the path between the two stations is parallel and close to the East Pacific Rise. The phase velocities we have observed are significantly lower than the global averages. The inversion for the oceanic part of the path gives a shear-wave velocity model with (1) unusually low velocities down to a depth of about 200 km, with a minimum of 4.1 km/s around 100 km, (2) normal or slightly less than normal velocities between depths of 200 km and about 400 km, and (3) a depression of the olivine-spinel phase boundary by about 50 km, or an equivalent velocity reduction around a depth of 450 km in a model without mantle discontinuities. We can make no definitive assertions regarding deeper anomalies in the mantle. The velocity anomalies below a depth of 200 km are consistent with the assumption that the temperature of the upper mantle between the low velocity zone and the spineloxide transition at 671 km in model 1066B, is elevated by 140° K relative to the average earth. Corrections to customary data processing procedures are offered that are designed to eliminate bias in estimates of dispersion at periods greater than 240 s.