L. Improta

• PhD Senior Seismologist
• Senior Researcher at Istituto Nazionale di Geofisica e Vulcanologia

We present high-resolution Vp and Vp/Vs models of the southern Apennines (Italy) computed using local earthquakes recorded from 2006 to 2011 with a graded inversion scheme that progressively resolves the crustal structure, from the large scale of the Apennines belt to the local scale of the normal-fault system. High-Vp bodies defined in the upper a...

The Val d'Agri basin in the Apennines seismic belt hosts the largest oil field in onshore Europe. High-quality recordings from a temporary dense network unravel a swarm of 111 small-magnitude events (ML ≤ 1.8) occurred in June 2006 during the first stage of wastewater injection into a high-rate well. High-precision relative locations define a pre-e...

Wastewater injection into a high-rate well in the Val d'Agri oilfield, the largest in onshore Europe, has induced swarm microseismicity since the initiation of disposal in 2006. To investigate the reservoir structure and to track seismicity, we performed a high-spatial resolution local earthquake tomography using 1,281 natural and induced earthquak...

We present the first high-quality catalog of early aftershocks of the three mainshocks of the 2016 central Italy Amatrice-Visso-Norcia normal faulting sequence. We located 10,574 manually picked aftershocks with a robust probabilistic, non-linear method achieving a significant improvement in the solution accuracy and magnitude completeness with res...

The anatomy of the Southern Apennines is a matter of compelling debate. Both thick- and thin-skinned tectonic models are proposed due to paucity of deep seismic constraints. We yield new and firmly constrained information on the velocity structure of the mountain range by using an innovative, nonlinear tomographic technique applied to refraction/wi...

The Irpinia Fault, also known as the Monte Marzano Fault System, located in the Southern Apennines (Italy), is one of the most seismically active structures in the Mediterranean. It is the source of the 1980, Ms 6.9, multi-segment rupture earthquake that caused significant damage and nearly 3,000 casualties. Paleoseismological surveys indicate that...

We present the first 3D crustal model of the epicentral region of the 1980, Mw 6.9, normal‐faulting Irpinia earthquake (southern Italy) determined by jointly interpreting the CROP‐04 deep seismic profile, a grid of commercial seismic lines, deep exploration wells, and a high‐resolution Local Earthquake Tomography. Despite numerous seismotectonic su...

Plain Language Summary The natural and man‐made seismic noise is commonly higher than the signal of small‐size earthquakes, which represents the vast majority of the seismic activity. Identifying these hidden events is crucial for gaining a better understanding of fault structures, their location, and overall characteristics. A powerful technique f...

We investigate the variability of Brune stress drop (Δσ), apparent stress (τa), and Savage–Wood radiation efficiency (ηsw=τa/Δσ), in the 2013–2014 Mw 5.0 earthquake sequence that struck the Matese area in the southern Apennines range of Italy. The sequence is clustered in a relatively small crustal volume in the 13–22 km depth range, which is great...

We present a detailed analysis of the small magnitude (ML < 3) Reservoir Induced Seismicity associated with the Pertusillo water reservoir located in the high seismic hazard zone of Val d'Agri (Southern Italy). We apply template‐matching detection to a 13‐month‐long dense passive survey, obtaining a final high‐precision double‐difference catalog of...

We present the first rupture models of the two mainshocks of the 2012 northern Italy sequence, determined by jointly inverting seismic and geodetic data. We aim at providing new insights into the mainshocks for which contrasting seismotectonic interpretations are proposed in literature. Sources' geometric parameters were constrained by seismic refl...

Tomographic images of the lithosphere are the first step to constrain the evolution of mountain belts and their interaction. By inverting new high‐quality P‐ and S‐wave arrivals that sample the entire lithosphere, we determined Vp and Vp/Vs models with reliable resolution in the critical depth range (40–80 km) where plates of the central Mediterran...

We present the results from a fully-unconstrained moment tensor inversion of induced seismic events in a complex and high seismic hazard region (Val d'Agri basin, Southern Italy). The study area hosts two well-documented cases of induced micro-seismicity linked to (a) a wastewater injection well of a giant oilfield (the largest in onshore Europe),...

We present the first high-resolution ultrashallow seismic image of a normal fault segment that ruptured the surface during the Mw 6.5 2016 Norcia earthquake (central Italy). This is the only fault, in the entire activated 25 km-long system, cutting a thick succession of Quaternary deposits, with an associated 3-m-high cumulative scarp. A 190-m-long...

In recent decades, geological modeling has significantly evolved, relying on the growing potential of hardware and software to manage and integrate vast datasets of 2D-3D geophysical underground data. Therefore, digitization and integration with other forms of data can often improve understanding of geological systems, even when using so-called vin...

An accurate survey of old and new datasets allowed us to probe the nature and role of fluids in the seismogenic processes of the Apennines mountain range in Italy. New datasets include the 1985–2021 instrumented seismicity catalog, the computed seismogenic thickness, and geodetic velocities and strains, whereas data from the literature comprise foc...

Minimum 1D velocity models and station corrections have been computed for the central Mediterranean area using two main data sets. The first one consists of accurate first arrival-time readings from 103 seismic events with magnitude (ML)≥3.5 recorded by the Italian National Seismic Network (RSN) and the AlpArray Seismic Network (AASN) in the period...

We present the first seismic reflection images of the Paganica and Bazzano basins, two tectonic basins developed in the hanging wall of the Paganica‐San Demetrio Fault System, the causative fault of the 2009 Mw 6.1 L'Aquila earthquake, Italy. Five high‐resolution seismic profiles were acquired along a main, 7 km long transect cutting across the str...

The Vettore–Bove normal fault system in central Italy ruptured during the 2016 MW 6.5 Norcia earthquake causing extensive surface faulting. At the Pian Grande di Castelluccio hanging wall basin, along the southern section of the fault ruptured during the MW 6.5 mainshock, we performed a high‐resolution seismic reflection/refraction experiment aimed...

Between November 2019 and November 2020, four seismic swarms occurred 7 km to the SW of the Benevento town in the Sannio region, which is one of the most seismic active areas in the Southern Apennines (Italy). These swarms were nearly collocated with the largest magnitude seismic event occurring on December 16, Mw3.9. According to the Database Macr...

A list of 100 focal mechanism solutions that occurred in Italy between 2015 and 2019 has been compiled for earthquakes with magnitude M ≥ 4.0. We define earthquake parameters for additional 22 seismic events with 3.0 ≤ M < 4.0 for two specific key zones: Muccia, at the northern termination of the Amatrice–Visso–Norcia 2016–2018 central Italy seismi...

We provide the first 3‐D resistivity image of the Pian Grande di Castelluccio basin, the main Quaternary depocenter in the hangingwall of the Mt.Vettore–Mt. Bove normal fault system (VBFS), responsible for the October 30, 2016 Mw 6.5 Norcia earthquake (central Italy). The subsurface structure of the basin is poorly known, and its relation with the...

We study the crustal velocity changes occurred at the restart of produced water injection at a well in the Val d'Agri oil field in January–February 2015 using seismic noise cross-correlation analysis. We observe that the relative velocity variations fit well with the hydrometric level of the nearby Agri river, which may be interpreted as a proxy of...

The RETRACE-3D project (centRal italy EarThquakes integRAted Crustal model) focused on the revision of all the available geological and geophysical data in the area interested by the 2016-2018 seismic sequence of central Italy, with the final aim to reconstruct a reliable and consistent 3D geological model of that area. It is based on a collaborati...

The mechanism by which faults interact each other is still a debated matter. One of the main issues is the role of pore-pressure diffusion in the delayed triggering of successive events. The 2016 Amatrice–Visso–Norcia seismic sequence (Central Apennines, Italy) provides a suitable dataset to test different physical mechanisms leading to delayed eve...

In this work, an approach is developed to study the seismicity associated with the impoundment and level changes of a water reservoir (reservoir induced seismicity – RIS). The proposed methodology features a combination of a semi-analytical poroelastic model with an earthquake nucleation approach based on rate-and-state frictional law. The combined...

In questo lavoro presentiamo il catalogo completo delle localizzazioni dei terremoti appartenenti alla più importante sequenza sismica avvenuta in Italia negli ultimi 30 anni, ovvero la sequenza sismica di Amatrice-Visso-Norcia (AVN) iniziata il 24 Agosto del 2016 in Appennino centrale. Si tratta di 102582 eventi sismici registrati dalle 129 stazio...

La sequenza sismica Amatrice-Visso-Norcia (AVN s.s. nel seguito) include il terremoto più forte avvenuto negli ultimi 30 anni in Italia ed è caratterizzata da molteplici eventi di magnitudo superiore a 5.0. La sequenza sismica è iniziata il 24 agosto 2016 con due terremoti di Mw 6.0 e Mw 5.4 nella zona di Amatrice (RI) ed è proseguita con altri due...

The Campi Flegrei caldera is a large volcanic complex lying in the Campanian Plain, Southern Italy. During its history the caldera experienced episodes of bradyseism and intense swarm seismicity. The mechanism leading to unrest episodes is still debated, and great efforts are ongoing to improve the knowledge of this structure and its evolution due...

Nel secondo quadrimestre 2017si sono verificati cinqueeventi di magnitudo superioreo uguale a 4.0,dei quali nessuno di magnitudo superiore a 5.0. Uno di questi, avvenuto il 21 agosto,pur essendo di magnitudo Md=4.0 (Mw=3.9) ha causato gravi danni nell’isola di Ischia.L’evento più forte del quadrimestre è un terremotoprofondo (ipocentro a profondità...

Nel terzoquadrimestre 2017si sono verificati dueeventi di magnitudo superioreo uguale a 4.0,dei qualinessuno di magnitudo superiore a 5.0. L’evento più forte,verificatosi il 19 novembre in provincia di Parma,è stato dimagnitudo MW=4.4eparametri ipocentralicon coordinate geografiche (44.66N,10.03E)eprofondità di22 km. Unsolo evento di magnitudo MW=4...

The 2016-2017 Central Italy seismic sequence struck with three M6+ normal-faulting earthquakes the junction zone between the Central and Southern Apennines. The area is characterized by a complex geological structure due to the occurrence of multiphased contractional (Mio-Pliocene) and extensional (Quanternary) deformation. Although the region was...

La sequenza sismica Amatrice-Visso-Norcia (AVN s.s. nel seguito) include il terremoto più forte avvenuto negli ultimi 30 anni in Italia ed è caratterizzata da molteplici eventi di magnitudo superiore a 5.0. La sequenza sismica è iniziata il 24 agosto 2016 con due terremoti di Mw 6.0 e Mw 5.4 nella zona di Amatrice (RI) ed è proseguita con altri due...

During the winter 2012, from 20 January to 4 February, the German oceanographic FS METEOR cruise (M86/3) took place in the central-southern Adriatic Sea in the frame of “Adria LithosPHere InvestigAtion” (ALPHA [Kopp et al., 2013]). The primary goal of the project was high-resolution tomographic imaging of the crust and lithospheric mantle underneat...

La sequenza sismica Amatrice-Visso-Norcia (AVN.s.s nel seguito) include il terremoto più forte avvenuto negli ultimi 30 anni in Italia. La sequenza sismica è iniziata il 24 agosto 2016 con due terremoti di Mw 6.0 e Mw 5.4 che hanno provocato ingenti danni e 294 morti; questi eventi sono stati seguiti da migliaia di aftershocks. Altri due terremoti...

Early aftershocks of the 2016 Mw 6.0 Amatrice, Mw 5.9 Visso and Mw 6.5 Norcia earthquakes in central Italy: analysis of the Italian Seismic Bulletin

In recent years it has become accepted that earthquake source can attain significant Non-Double-Couple (NDC) components. Among the driving factors of deviation from normal double-couple (DC) mechanisms there is the opening/closing of fracture networks and the activation of pre-existing faults by pore fluid pressure perturbations. This observation m...

Nella Struttura Terremoti dell’INGV la Linea di Attività T5 “Sorveglianza sismica ed operatività post- terremoto” si occupa delle attività di sviluppo di strumenti e procedure per la valutazione in tempo reale degli effetti di terremoti e tsunami e della gestione delle emergenze sismiche. Uno dei suoi obiettivi del 2015 era la formalizzazione dei p...

Since 2006 wastewater has been injected below the Val d’Agri Quaternary basin, the largest on-land oilfield in Europe, inducing micro-seismicity in the proximity of a high-rate injection well. In this study, we have the rare opportunity to revise a massive set of 2D/3D seismic and deep borehole data in order to investigate the relationship between...

We present a 2-D subsurface image of the Paganica Fault from a high-resolution refraction tomography and detailed geological investigation carried out across part of the north-western segment of the 20 km-long Paganica – San Demetrio fault-system, and which was responsible of the 6 April 2009 Mw 6.1 L’Aquila earthquake (central Italy). We acquired...

In the framework of INGV Earthquake Department organization, the Research Activity named "Sorveglianza sismica ed operatività post-terremoto" (Seismic survey and post-earthquake operativity" (T5) takes care of the development of tools and procedures for the real time evaluation of earthquake effects and the management of seismic emergency. One of m...

The poster resumes the results of high-resolution seismic reflection profiling across Bazzano and Paganica Basin and across the shallow segments of the Paganica-S. Demetrio Fault, which has been indicated as the causative fault of the 6th April 2009 (Mw 6.3) earthquake. The seismic data were collected along four dense wide-aperture profiles, that r...

Water level reservoir affects the underlying crust stress state through the poroelastic response to the weight of the water volume stored and by the consequent fluid movement. The perturbation of crustal stress state has been associated in some cases with seismic events, with maximum magnitudes ranging from -1.0 and below up to magnitude 6.3, as re...

The Val d’Agri Quaternary basin is located within the Southern Apennine extensional belt, hosting the largest oilfield in Europe. Since 2006 wastewaters coming from oil production were re-injected by a single disposal well into the reservoir, represented by the carbonates of the Apulian platform. Consequently, induced micro-seismicity (219 events,...

The Val d'Agri basin in the Apennines extensional belt hosts the largest oilfield in onshore Europe. High-quality recordings from a temporary dense network unravel a swarm of 111 small-magnitude events (ML ≤ 1.8) occurred in June 2006 during the first stage of wastewater injection into a high-rate well. 3D absolute locations and high-precision rela...

Typically the term " induced seismicity " is used to refer minor earthquakes and tremors caused by human activities that alter the stresses and strains on the Earth's crust. In the last years, the interest in the induced seismicity related to fluids (oil and gas, and geothermal resources) extraction or injection is increased, because it is believed...

The relationship between anthropic operations and seismic events has increasingly drawn the attention of the international scientific community during the last decades. Especially in Italy and after the Emilia seismic sequence of May 2012, this topic sparked a new particular interest. Several round tables and ad-hoc commissions were set up in order...

The Val d’Agri in the southern Apennines of Italy is an active extensional basin hosting the largest European onshore oil field. The present contribution aims to analyze micro-earthquakes occurred in the period 2006-2014 close to the injection well and in the nearby area in order to evaluate the spatio-temporal evolution of the seismicity and its c...

Durante il mese di ottobre 2014 si è svolta nel Mar Ionio una campagna oceanografica franco-tedesca denominata DIONYSUS, acronimo di “Deep structure of the IONian sea and east sicilY : wide-angle seismic SUrvey ofthe calabria Subduction zone and tethys margins”, organizzata dal personale degli Istituti francesi del Laboratoire Domaines Océaniques (...

The Val d’Agri is an extensional basin in the southern Apennines seismic belt (Italy) that hosts the largest European inland oil field. In this study, we analyze high-quality recordings from a dense temporary network of 23 stations of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) toinvestigate a swarm of 109 micro-earthquakes (ML<1.8),...

The evolution of the Apennines thrust-and-fold belt is related to heterogeneous process of subduction and continental delamination that generates extension within the mountain range and compression on the outer front of the Adria lithosphere. While normal faulting earthquakes diffusely occur along the mountain chain, the sparse and poor seismicity...

The Val d'Agri extensional basin in Southern Italy, which is one of the regions in Italy with the highest seismogenic potential (up to M7 earthquakes), hosts the largest productive onshore oil field in Europe. Continuous waveforms recorded during a 13-months-long seismic experiment in 2005-2006 by a very dense seismic network were analyzed by an in...

[1] A 10 Hz-sampling frequency GPS station was installed near L'Aquila a few days before the April 6th 2009 Mw6.1 earthquake. It recorded displacement waveforms during the main shock and the largest Mw5.4 aftershock of April 7th. The horizontal components of the main shock contain a high-amplitude (43 cm peak-to-peak) nearly-harmonic (1 Hz) wave tr...

[1] Wavefield polarization is investigated using 200 seismograms recorded by a network of 20 stations installed on rock outcrops in the Val d'Agri region that hosts the largest oil fields in the southern Apennines (Italy). Polarization is assessed both in the frequency and time domains through the individual-station horizontal-to-vertical spectral...

Seismic hazards in extensional regions are mostly posed by high-angle normal faults and deep hanging-wall basins that can promote significant ground motion amplifications. Characterized by strong lateral velocity variations, these structures represent challenging targets for seismic exploration. In this paper, we show that pre-stack depth migration...

Alle ore 02.03 UTC di domenica 20 maggio 2012, la Rete Sismica Nazionale (RSN [Amato and Mele, 2008; Delladio, 2011]) dell’Istituto Nazionale di Geofisica e Vulcanologia (INGV) ha registrato un evento simico di magnitudo locale 5.9 che è stato avvertito in gran parte dell’Italia centro-settentrionale; l’evento è stato localizzato sotto la valle del...

On May 20th 2012 (Sunday) an earthquake (ML 5.9) hit Northern Italy at 02:03 UTC,. The National Seismic Network [Amato and Mele, 2008; Delladio, 2011] of the Istituto Nazionale di Geofisica e Vulcanologia (INGV) located the hypocenter below the Po Valley in the Emilia region (44.89° N, 11.23° E, 6.3 km depth). Just after the mainshock, the INGV str...

The Val d’Agri (VA) Quaternary basin in the southern Apennines extensional belt hosts the largest oilfield in onshore Europe and normal-fault systems with high (up to M7) seismogenic potential. Frequent small-magnitude swarms related to both active crustal extension and anthropogenic activity have occurred in the region. Causal factors for induced...

We present high-resolution Vp models of the Middle Aterno basin obtained by multi-scale non-linear controlled-source tomography. Seismic data have been collected along four dense wide-aperture profiles, that run SW-NE for a total length of ~6 km in the hangingwall of the Paganica-S. Demetrio Fault, source of the 6th April 2009 (Mw 6.3) L’Aquila nor...

p>Rapid-response seismic networks are an important element in the response to seismic crises. They temporarily improve the detection performance of permanent monitoring systems during seismic sequences. The improvement in earthquake detection and location capabilities can be important for decision makers to assess the current situation, and can pro...

Central Apennines (Italy) is affected by repeated large normal-faulting crustal earthquakes. The 6th April 2009 Mw 6.1 event damaged L'Aquila town and surroundings, causing 308 deaths. Seismological, geodetic and geological analyses have defined the geometry and kinematics of the source of the 2009 mainshock (Paganica Fault) and of the structures a...

Articolo all'interno del volume “Sintesi dei lavori del Workshop EDURISK 2002 – 2011 | 10 anni di progetti di educazione al rischio”, n. 13, ISSN 2039-6651, Miscellanea INGV, 2012

The largest dataset ever recorded during a normal fault seismic sequence was acquired during the 2009 seismic emergency triggered by the damaging earthquake in L'Aquila (Italy). This was possible through the coordination of different rapid-response seismic networks in Italy, France and Germany. A seismic network of more than 60 stations recorded up...

On April 6 (01:32 UTC) 2009 a M-W 6.1 normal faulting earthquake struck the axial area of the Abruzzo region in central Italy. The earthquake heavily damaged the city of L'Aquila and its surroundings, causing 308 casualties, 70,000 evacuees and incalculable losses to the cultural heritage. We present the geometry of the fault system composed of two...

The largest dataset ever recorded during a normal fault seismic sequence was acquired during the 2009 seismic emergency triggered by the damaging earthquake in L'Aquila (Italy). This was possible through the coordination of different rapid-response seismic networks in Italy, France and Germany. A seismic network of more than 60 stations recorded up...

We use local earthquake tomography and background seismicity to investigate static and transient features of the crustal velocity structure in the Val d'Agri (southern Apennines, Italy), one of the regions in central Mediterranean with the highest seismogenic potential. The upper crust is dominated by two broad high-velocity anticlines of the burie...

The Southern Apennines range of Italy presents significant challenges for active fault detection due to the complex structural setting inherited from previous contractional tectonics, coupled to very recent (Middle Pleistocene) onset and slow slip rates of active normal faults. As shown by the Irpinia Fault, source of a M6.9 earthquake in 1980, maj...

A two-step imaging procedure, including pre-stack depth migration (PSDM) and non-linear multiscale refraction tomography, was applied to dense wide-aperture data with the aim of imaging the causative fault of the 1980, M6.9, Irpinia normal faulting earthquake in a very complex geologic environment. PSDM is often ineffective for ultrashallow imaging...

Il 6 aprile 2009 (3.32 locali) un terremoto di Mw 6,3 ha colpito la regione Abruzzo (Italia centrale) producendo un enorme danno alla città de L'Aquila e ai paesi limitrofi causando circa 300 morti e 60.000 senza fissa dimora. A seguito di questo evento sismico, la struttura di Pronto Intervento dell’INGV (Istituto Nazionale di Geofisica e Vulcanol...