Wave Gradiometry for EarthScope Seismic and Strain Data

EarthScope地震和应变数据的波动测量。兰斯顿，首席研究员孟菲斯大学地震研究和信息中心一种新的经验方法来分析地震波，称为波梯度法，正在被用来研究地震数据记录的EarthScope移动阵列和校准板边界观测（PBO）钻孔应变仪。 通过计算地震台阵的应变和旋转，可以确定远距离大地震的地震波的定量属性，如地震波的速度、传播方位角和振幅变化。 这些量的经验地图，然后首先确定异常区域的地壳和地幔，然后定量地确定大规模的地震速度结构的北美大陆。 地震梯度测量技术允许确定由地震波引起的区域应变场，以作为已知的参考应变，与PBO应变计观察到的应变进行比较。 正通过矩阵数学和时间序列分析方法将参考应变和观测应变结合起来，以便精确校准各个钻孔应变仪。 PBO应变仪的校准是使应变数据对板块边界观测站内活动地质过程的地震和构造研究有用的重要步骤。

Wave Gradiometry for EarthScope Seismic and Strain DataCharles A. Langston, Principal InvestigatorCenter for Earthquake Research and InformationUniversity of MemphisA new empirical method to analyze seismic waves, called wave gradiometry, is being used to study earthquake data recorded by the EarthScope Transportable Array and to calibrate Plate Boundary Observatory (PBO) borehole strain meters. Quantitative attributes of seismic waves from large, distant earthquakes such as their speed, azimuth of propagation, and amplitude changes are being determined by computing seismic array strains and rotations. Empirical maps of these quantities are then used to first identify anomalous regions of the crust and mantle and then to quantitatively determine large-scale seismic velocity structure of the North American continent. Seismic gradiometry techniques allow the determination of regional strain fields induced by the seismic waves to serve as a known reference strain to compare with observed strains from PBO strain meters. The reference and observed strains are being combined through matrix mathematics and time series analysis methods to produce precise calibration of individual borehole strain meters. Calibration of the PBO strain meters is an essential step in making the strain data useful for seismic and tectonic studies of active geological processes within the Plate Boundary Observatory.