Evaluation of macroseismic intensity, strong ground motion pattern and fault model of the 19 July 2019 Mw5.1 earthquake west of Athens

This paper presents a joint analysis of instrumental and macroseismic data regarding the 19 July 2019, Greece Mw5.1 earthquake occurred west of Athens. This earthquake ruptured a blind, south-dipping normal fault, 23 km WNW of the center of Athens, while its relocated epicentre lies in close vicinity to the one of the 1999 Mw6.0 earthquake. The maximum macroseismic intensity of the 2019 mainshock reached IEMS98 = 7.5. Scarce damage and intensities up to 5–6 were reported in the epicentral area. Higher intensities were observed at larger distances, 12–15 km east and ESE of the epicentre, alongside the banks of Kifissos River, likely related to ground motion amplification due to soft alluvial formations. Similar selectivity of increased ground motions to the east of the epicentre with respect to other azimuths, also observed during the 1981 and 1999 earthquakes, supports eastward rupture directivity of the 2019 mainshock, an effect that is possibly common for the region’s fault system. Damping of seismic effects was observed east of Aegaleo Mountain, a structure suggested to impose a stopping phase in the time histories of the 1999 and 2019 earthquakes (Fig. A1).