2-D finite element modeling of both coseismic and interseismic deformation was performed along a transect across the seismogenic fault of the Mw=7.3, November 2017 Lurestan earthquake (Zagros Mountains). In order to extract information on the time-space distribution of uplift along the same transect, an investigation of the large-scale features of topography and river network was also carried out. Constraints from the spatial distribution of mean elevation, local relief and normalized channel steepness index (ksn), combined with those from river longitudinal profiles and transformed river profiles (chi-plots), were integrated with the results of geomorphological analyses aimed at the reconstruction of the development of the fluvial network. Despite the much longer timescale over which topography grows and/or rivers respond to tectonic or climatic perturbations with respect to even multiple seismic cycles, the outputs of the finite element model yield fundamental information on the source of the late part of the spatiotemporal evolution of surface uplift recorded by the geomorphological signature. Model outputs shed new light into the processes controlling relief evolution in an actively growing mountain belt underlain by a major blind thrust. They point out how co-seismic slip controls localized uplift of a prominent topographic feature ­– defining the Mountain Front Flexure – located above the main upper crustal ramp of the principal basement thrust fault of the region, while continuous displacement along the deeper, aseismic portion of the same basement fault controls generalized uplift of the whole crustal block located further to the NE, in the interior of the orogen.

The Zagros thrust belt formed due to the convergence between the Arabian and Eurasian plates during the closure of the Neo-Tethys Ocean. GPS measurements show that the northward relative motion of the Arabian Plate is still active today. This active drift produces high-magnitude earthquakes along the Zagros thrust belt, such as the Iran-Iraq border seismic event of November 12, 2017 (Mw = 7.3), nucleated along the “Mountain Front Fault”. The aim of this work is to study the inter-seismic and co-seismic deformation that eventually leads to the nucleation of important seismic events in the study area. A 2-D finite element model has been performed starting from published geological sections and relevant seismological datasets, integrated with geo-mechanical parameters of the rocks. The results of finite element modeling (FEM), including predicted uplift pattern and rate along the analysed crustal section, are compared with a tectonic geomorphology analysis in order to unravel the most reliable tectonic scenario for the active tectonic setting of the study area.

In this work we examine the seismicity of Montefeltro, a historical region of central Italy located between the northern Apennines and the Republic of San Marino towards the northern Adriatic coast. The seismicity of the northern Apennines region is mainly concentrated along the chain within a seismogenic layer that extends from about 5 to 15 km depth. Recently, important seismic sequences occurred in the central-northern Apenninic chain with magnitudes exceeding 5.5 (Colfiorito 1997, Mw 6.0; L’Aquila 2009 Mw 6.3; Emilia 2012, Mw 6.1; Amatrice 2016, Mw 6.5). Instead, the seismicity of Montefeltro, as recorded in the past three decades, appears quite widespread and discontinuous over time, except in some phases of intense activity. The magnitudes detected so far vary essentially from low to moderate, lower than 4.5 for the largest events. Unfortunately, the region that includes the Montefeltro is still not adequately monitored, therefore a detailed analysis of the background seismicity, the calculation of focal mechanisms for low magnitude events, and a more reliable estimate of the b-value is limited. To better define these parameters, a temporary seismic network has been set up starting from December 2018 to integrate the instrumental coverage provided by the Italian National Seismic Network (RSN). The analysis of the seismic activity occurred in the period January 2005 – up to now shows a sporadic, rather diffuse background seismicity marked by small magnitude seismic sequences strongly clustered in time and space. The most important sequences occurred in September-October 2005 (M=3.2) and August-September 2006 (M=3.7), nearby the towns of Macerata Feltria and Casteldelci, respectively. The spatio-temporal evolution of these main episodes highlights an energy release consistent with swarm-like activity. Others clusters of less intensity and duration were observed in January 2011 (ML 2.2, 15 events), September 2012 (ML 2.8, 6 events), and July 2015 (ML 2.3, 10 events). These bursts are confined in the upper crust contrary to the swarm-like seismicity which extends up to ~25 km depth. Another major feature of the seismicity pattern is represented by the occurrence of events even in the lower crust and in the upper mantle down to at least 50 km depth.