Dynamic strains have never played a role in determining local earthquake magnitudes, which are routinely set by displacement waveforms from seismic instrumentation (e.g., ML⁠). We present a magnitude scale for local earthquakes based on broadband dynamic strain waveforms. This scale is derived from the peak root‐mean‐squared strains (⁠A⁠) in 4589 records of dynamic strain associated with 365 crustal earthquakes and 77 borehole strainmeters along the Pacific‐North American plate boundary on the west coast of the United States and Canada. In this data set, catalog moment magnitudes range from 3.5≤Mw≤7.2⁠, and hypocentral distances range from 6≤R≤500 km⁠. The 1D representation of geometrical spreading and attenuation of A common to all strain data is logA0(R)=−0.00072R−1.45log(R)⁠. After correcting for instrument gain, site terms, and event terms, the magnitude scale, MDS=logA−logA0(R)−log(3×10−9)⁠, scales as ≈0.92Mw with a residual standard deviation of 0.19. This close association with Mw holds for events east of the −124° meridian; west of this boundary, however, a constant correction of 0.41 is needed to adjust for additional along‐path attenuation effects. As a check on the accuracy of this magnitude scale, we apply it to dynamic strain records from three strainmeters located in the near field of the 2019 M 6.4 and 7.1 Ridgecrest earthquakes. Results from these six records are in agreement to within 0.5 magnitude units, and five out of six records are in agreement to within 0.34 units.

中文翻译：

---

来自动态应变的地震震级

动态应变从未在确定当地地震震级方面发挥作用，通常由地震仪器（例如，ML?）的位移波形设置。我们提出了基于宽带动态应变波形的局部地震震级。该比例源自美国西海岸太平洋-北美板块边界沿线的 365 次地壳地震和 77 个钻孔应变计的 4589 次动态应变记录中的峰值均方根应变 (⁠A⁠) 和加拿大。在该数据集中，目录矩震级范围为 3.5≤Mw≤7.2⁠，震源距离范围为 6≤R≤500 km⁠。所有应变数据共有的 A 的几何扩展和衰减的一维表示是 logA0(R)=−0.00072R−1.45log(R)⁠。在校正仪器增益、站点项和事件项后，震级尺度 MDS=logA−logA0(R)−log(3×10−9)⁠，缩放为 ≈0.92Mw，残差标准偏差为 0.19。这种与 Mw 的密切关联适用于 -124° 子午线以东的事件；然而，在此边界以西，需要进行 0.41 的恒定校正以调整额外的沿路径衰减效应。为了检查此震级的准确性，我们将其应用于来自位于 2019 年 M 6.4 和 7.1 Ridgecrest 地震近场的三个应变计的动态应变记录。这六个记录的结果在 0.5 个震级单位内一致，六个记录中有五个在 0.34 个单位内一致。然而，在此边界以西，需要进行 0.41 的恒定校正以调整额外的沿路径衰减效应。为了检查此震级的准确性，我们将其应用于来自位于 2019 年 M 6.4 和 7.1 Ridgecrest 地震近场的三个应变计的动态应变记录。这六个记录的结果在 0.5 个震级单位内一致，六个记录中有五个在 0.34 个单位内一致。然而，在此边界以西，需要进行 0.41 的恒定校正以调整额外的沿路径衰减效应。为了检查此震级的准确性，我们将其应用于来自位于 2019 年 M 6.4 和 7.1 Ridgecrest 地震近场的三个应变计的动态应变记录。这六个记录的结果在 0.5 个震级单位内一致，六个记录中有五个在 0.34 个单位内一致。