Online Material: Supplemental table, figures. On 20 May 2012, at 02:03:52 GMT, an earthquake with M w 6.1 (Regional Centroid Moment Tensor [RCMT]; http://www.bo.ingv.it/RCMT) occurred in northern Italy striking a densely populated area. The mainshock was followed a few hours later by two severe aftershocks having the same local magnitude ( M L 5.1, Fig. 1a), and by hundreds of smaller aftershocks. Nine days later, on 29 May, at 07:00:03 GMT, a second event with moment magnitude M w 6.0 (RCMT; http://www.bo.ingv.it/RCMT) occurred to the west, on an adjacent fault segment. This event was also followed by hundreds of aftershocks, three of them having local magnitudes 5.3, 5.2, and 5.1 (Fig. 1a; locations from Istituto Nazionale di Geofisica e Vulcanologia, hereinafter INGV; http://iside.rm.ingv.it/; Malagnini et al. , 2012; Scognamiglio et al. , 2012). Despite the moderate number of casualties if compared to other major events in Italian history, the economic loss was extremely high, resulting in about EUR 5 billion (AON Benfield, 2012; http://www.aon.com/), as the majority of Italian industrial activities and infrastructure concentrate in this area, the eastern Po plain, which is the largest sedimentary basin in Italy. Figure 1. (a) Simplified geological sketch of the Po plain and surrounding northern Apennines and Southern Alps fold‐and‐thrust belts. Key to symbols: stars, earthquakes of M >5 of the 2012 Emilia–Romagna seismic sequence, dimension proportional to the magnitude; dark gray areas, Composite Seismogenic Sources (CSS) of the DISS database (http://diss.rm.ingv.it), the upper tip of the fault plane is highlighted in black. Focal mechanisms of the 20 and 29 May 2012 earthquakes are from the TDMT database (http://cnt.rm.ingv.it/tdmt.html). (b) Simplified geological sections crossing the Po plain and showing thickness variation of the Plio‐Quaternary sedimentary sequence correlated with syncline–anticline pairs of the northern Apennines and Southern Alps thrust belts. Modified from Cassano et al. (1986), sections 1, 2, …