The 19 September 2022, Michoacan earthquake (Mw 7.6): a case study for the observation of Environmental effects triggered (EEEs) and application of the ESI-07 scale

Mexico is characterized by a high seismicity, mostly related with the Mexican subduction zone where the Rivera and Cocos plate subducts under the North American plate. Although some historic destructive earthquakes are of crustal origin, most of the earthquakes with magnitude greater than 7 are located on the subduction and greatly affect the populations and infrastructures of the Pacific coast of the country. Here we investigate a Mw 7.6 earthquake occurred on September 9, 2022, at 18:05:06 (UTC time) with reverse kinematic and an epicenter located onshore, 35 km SW of Aguililla and with a focal depth 16.2 km (USGS, 2022). We document the Earthquake Environmental Effects (EEEs) and we apply the Environmental Seismic Intensity scale (ESI-2007; Michetti et al., 2007), which is based solely on effects on the natural environment. EEEs can be divided into primary effects (primary surface ruptures, tectonic uplift\subsidence) and secondary effects (e.g., ground cracks, slope movements, liquefaction processes, anomalous waves and tsunamis, hydrogeological anomalies, tree shaking, dust clouds and jumping stones). Figure 1 shows an example of ground cracks along the seashore at Mezcala, Michoacán.