A local seismic magnitude scale, ML^P, has been developed for the United Kingdom (UK) using automated measurements of 8902 half peak-to-peak vertical component seismic P-wave displacement amplitudes from 630 earthquakes. The measurement time window increases with source-to-receiver range such that ML^P is sensitive to the dominant phase within the P-wavetrain at a given distance. To avoid contamination due to low-frequency noise, the P-wave amplitude measurements are made in the 1.5–30 Hz passband. A least-squares inversion was undertaken to estimate source size, distance and station effects. The distance effect values suggest that P-wave amplitude attenuation across the UK is low when compared to other tectonically stable regions. The station effects are broadly consistent with UK geology, with signal amplification observed within the sediments towards the south-east of the country. ML^P has been tied to the UK local magnitude scale routinely estimated by the British Geological Survey (BGS, determined using S waves, and here denoted ML^BGS). For earthquakes with ML^BGS > 3, ML^P exhibits a closer correspondence to the moment magnitude than ML^BGS (i.e. ML^P≈M_w). It is tentatively suggested that this reduction in bias is caused by the P-wave scale being less affected by along-path attenuation. The difference with respect to physical source scaling helps explain the divergence of the ML^BGS and ML^P scales at ML > 3. ML^P allows a robust estimate of event size to be made for small events which predominantly generate P waves, for example, near-surface explosions. ML^P values have been calculated for 239 explosive events, mostly mining blasts and munitions disposal. Although there is significant scatter, explosive events exhibit elevated ML^P values compared to ML^BGS, consistent with explosions generating proportionally more compressional wave energy than earthquakes. For example, 33 explosions at sea exhibit a median ML^P–ML^BGS value of 0.50 mag units. Despite its sensitivity to P-wave amplitude, ML^P is not a more consistent estimator of explosive source size than ML^BGS; the magnitude residuals (station estimate − event estimate) are slightly less for ML^BGS compared to ML^P. This is primarily due to variability of the P-wave amplitudes that cannot be explained by a 1-D distance correction. ML^P should be considered as an additional tool for characterizing small seismic events within the UK.

中文翻译：

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使用P波振幅的英国当地地震震级标度ML ^P

使用自动测量来自630次地震的8902个半峰峰垂直分量地震P波位移幅度，为英国（UK）开发了本地地震震级标度ML ^P。测量时间窗口随着源到接收器范围的增加而增加，使得ML ^P对给定距离的P波列中的主导相位敏感。为避免低频噪声造成的污染，在1.5–30 Hz的通带中进行P波幅度测量。进行了最小二乘反演，以估算震源大小，距离和台站效应。距离效应值表明P与其他构造稳定区域相比，整个英国的波振幅衰减很小。台站效应与英国地质大体一致，在该国东南部的沉积物中观察到信号放大。ML ^P已与英国地质调查局（BGS，使用S波确定，此处表示为ML ^BGS）常规估算的英国当地震级标度联系在一起。对于具有ML地震^BGS  > 3，ML ^P表现出的瞬间幅值低于ML仔细对应^BGS（即ML ^P ≈M_瓦特）。暂时建议这种偏见的减少是由P引起的。波尺度受沿径衰减的影响较小。物理源缩放比例方面的差异有助于解释ML> 3时ML ^BGS和ML ^P缩放比例的差异^{。ML P}可以对主要生成P波的小事件（例如，接近P波）进行事件大小的可靠估计。面爆炸。ML ^P值是针对239起爆炸事件（主要是采矿爆炸和弹药处置）计算得出的。尽管有很大的散布，但与ML ^BGS相比，爆炸事件的ML ^P值升高了，这与爆炸产生比地震成比例地更多的压缩波能量一致。例如，海上发生的33起爆炸的ML ^P –ML ^BGS中值为0.50 mag单位。尽管它对P波振幅敏感，但ML ^P并不是比ML ^BGS更一致的爆炸源尺寸估算器。与ML ^P相比，ML ^BGS的幅度残差（站估计-事件估计）略小。这主要是由于无法通过一维距离校正来解释的P波振幅的变化。ML ^P 应被视为表征英国境内小地震事件的附加工具。