Abstract Man-made seismicity is a response of the brittle crust to fluid injection at depth and to the subsequent increase in pore-pressure and stress field perturbations. In Oklahoma, where the sharp increase in earthquake rate correlates with injection operations, we show that the earthquake-size distribution can differ significantly on the volume of injected fluid. The size distribution of M < 3.5 earthquakes exhibits a near-constant slope b , while significant variation of b -values (from b ≈ 1 to b > 2) may be documented for larger magnitude ranges. This change shows statistically significant positive dependence on injection activity. In addition, largest events occur at the border of the injection area at some distance from massive injection, and in the periods of steady injection rate. These observations suggest that a deficit of large induced earthquakes under conditions of high injection rate can be accompanied by an overall increase of natural seismicity along pre-existing faults in the surrounding volume, where large events are more likely to be triggered over longer space-time scales.

中文翻译：

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俄克拉荷马州石油生产区发生大地震的情况

摘要 人为地震活动是脆性地壳对深部流体注入以及随后的孔隙压力和应力场扰动增加的响应。在俄克拉荷马州，地震率的急剧增加与注入操作相关，我们表明地震大小分布可能因注入流体的体积而显着不同。M < 3.5 地震的大小分布呈现出接近恒定的斜率 b ，而对于更大的震级范围，可以记录 b 值的显着变化（从 b ≈ 1 到 b > 2）。这种变化显示出对注射活动的统计显着的正依赖性。此外，最大的事件发生在距大量注入一定距离的注入区域的边界处，并且发生在稳定注入速率的时期。