In seismic hazard analyses, it is common practice to consider only earthquakes with magnitudes greater than 5 while assuming that smaller events cannot damage engineered structures. However, this assumption may not hold for induced seismicity, where earthquakes often occur at very shallow depths with rupture distances of only a few kilometers. The steep attenuation of ground motions within the first 10 km in small-magnitude events can yield median short-period accelerations that exceed those predicted by conventional ground-motion models. The combination of higher ground-motion amplitudes and elevated earthquake rates challenges the assumption that earthquakes smaller than magnitude 5 cannot cause damage to earth structures. This study evaluates the damage potential of small-to-moderate (magnitudes 3–5) induced earthquakes occurring at shallow depths on the seismic performances of earth canal dykes. The earthquake scenarios and ground motions selected for the assessments represent features expected from induced seismicity associated with wastewater injection. For dykes with a yield acceleration of 0.1 g , the results indicate that significant deformations (10 cm) may occur during earthquakes with magnitudes between 3.0 and 4.0 at a rupture distance of about 3 km. The methodology presented herein also provides a framework for assessing the minimum threshold magnitudes of other engineered systems in regions affected by induced seismicity.
Macedo et al. (Wed,) studied this question.