Giulia Sgattoni

National Institute of Geophysics and Volcanology | INGV · Sezione di Bologna

The vibration modes of the ground have been described both in the 1D and 2D case. The 1D resonance is found on geological structures whose aspect ratio is low, that is on layers with a lateral width much larger than their thickness. A typical example is that of a horizontal soft sediment layer overlying hard bedrock. In this case, the 1D resonance...

Any stratigraphic reconstruction by means of surface geophysical methods is affected by the non-uniqueness of data inversion and by the resolution-depth tradeoff. The combination of different geophysical techniques can reduce the number of degrees of freedom of the problem. We focus on two low-impact single-station geophysical techniques: microtrem...

Relative location methods are commonly used to precisely locate earthquake clusters consisting of similar waveforms. Repeating waveforms are often recorded at volcanoes, where, however, the crust structure is expected to contain strong heterogeneities and therefore the 1D velocity model assumption that is made in most location strategies is not lik...

We introduce a back-projection method to locate tremor sources using products of cross-correlation envelopes of time series between seismic stations. For a given subset of n stations, we calculate the (n − 1)th-order product of cross-correlation envelopes and we stack the back-projected products over combinations of station subsets. We show that co...

A key element for assessing seismic hazard and risk is the availability of a comprehensive dataset on past earthquakes. Here we present the rationale, structure and contents of CFTI5Med ( https://doi.org/10.6092/ingv.it-cfti5 ), the 2018 version of the Catalogue of Strong Earthquakes in Italy: a large multidisciplinary effort including historians,...

This paper illustrates the activities of EMERSITO, an emergency task force of the Istituto Nazionale di Geofisica e Vulcanologia (INGV, Italy) devoted to site effects and microzonation studies, during the seismic sequence that occurred close to the Adriatic coast in Central Italy since November 9th, 2022, following the Mw 5.5 mainshock localised in...

The use of the HVSR (Horizontal-to-Vertical Spectral Ratio) method on single-station microtremor measurements is well documented in small alluvial plains for bedrock mapping. In large sedimentary basins, like the Po Plain, its application is still debated. To shed some light on this issue, we investigated two seismogenic structures buried below the...

Knowing the location, the extent and the characteristics of any earthquake-induced environmental phenomenon is becoming an increasingly pressing need for civil protection agencies and local administrations. In particular, earthquake-triggered landslides are known for being among the most important sources of secondary hazard, as they may cause sign...

Bedrock mapping is essential for understanding seismic amplification, particularly in sediment-filled valleys or basins. However, this can be hard in urban environments. We conducted a geophysical investigation of the sediment-filled Bolzano basin in Northern Italy, where three valleys converge. This study uses low-impact, single-station geophysica...

Effective site characterization in highly urbanized coastal lowlands requires accurate stratigraphic and geophysical investigations. In these regions, which typically host shallowly buried paleovalley systems formed in response to Quaternary glacio‐eustatic fluctuations, the marked lithologic contrast between soft sediment paleovalley fills and the...

The study of ground resonances is important to assess seismic site amplification and to infer information on the geometrical and mechanical properties of the resonating structures. 1D- and 2D-type resonances imply different dynamic behavior that can be distinguished by inspecting the individual spectral components of single-station microtremor meas...

All'inizio del 2018 è stata pubblicata una nuova versione del Catalogo dei Forti Terremoti in Italia e nell'area mediterranea, denominata CFTI5Med (Guidoboni et al., 2018). La nuova versione giunge a 11 anni dalla precedente versione (Guidoboni et al., 2007) e ad oltre vent'anni dalla prima uscita (Boschi et al., 1995). Il CFTI, che è basato su una...

Double-difference (DD) seismic data are widely used to define elasticity distribution in the Earth's interior and its variation in time. DD data are often pre-processed from earthquake recordings through expert opinion, whereby pairs of earthquakes are selected based on some user-defined criteria and DD data are computed from the selected pairs. We...

Double differences (DD) seismic data are widely used to define elasticity distribution in the Earth's interior, and its variation in time. DD data are often pre-processed from earthquakes recordings through expert-opinion, where couples of earthquakes are selected based on some user-defined criteria, and DD data are computed from the selected coupl...

Measuring ground resonances is of great importance for seismic site amplification studies. The task is usually addressed with the common H/V (horizontal to vertical spectral ratio) approach, which is widely used for both microzonation studies and stratigraphic imaging. Peaks on the H/V function are used to identify ground resonance frequencies, usu...

Katla is one of the most active volcanoes in Iceland and is characterised by persistent seismicity. It is partly covered by the Mýrdalsjökull glacier and its historic activity is dominated by phreatomagmatic eruptions within the caldera associated with catastrophic glacial floods. In July 2011 a sudden jökulhlaup was released from the glacier, asso...

In this work, we present the geophysical characterization of 11 sites of the RAN network, located in Irpinia (Southern Italy) and in Stromboli Island, as part of a larger seismic hazard study. 60% of the surveyed seismic stations resulted to belong to a subsoil class different from what expected from the geological evidence. In all cases, the latte...

The Catalogo dei Forti Terremoti in ltalia (Catalogue of Strong Italian Earthquakes) is the most important outcome of a well-established collaboration between the Istituto Nazionale di Geofisica (ING; since 2000 Istituto Nazionale di Geofisica e Vulcanologia, INGV), the leading Italian institution for basic and applied research in seismology and so...

Una delle principali attività svolte tra il 2016 e il 2017 nell’ambito delll'Allegato B2 dell’Accordo-Quadro DPC-INGV 2012-2021 ha riguardato il grande patrimonio informativo sugli effetti ambientali sismo-indotti presente nella banca-dati del Catalogo dei Forti Terremoti in Italia (CFTI). Questi dati sono solo in minima parte accessibili nella sua...

La necessità di rendere disponibili i risultati delle attività svolte tra il 2016 e il 2017 nell’ambito della Convenzione B2 INGV-DPC (Obiettivo 1 - Task A) e la scelta di rendere accessibili contenuti nora non pubblici presenti nella banca dati CFTI (Catalogo dei Forti Terremoti in Italia, Guidoboni et al., 2007), hanno reso indispensabile lo svil...

A peculiar cluster of seismicity near the tip of Sandfellsjökull on the eastern flank of Katla volcano in southern Iceland has been analyzed in detail using data from a temporary seismic network. A total of 300 events were detected between July 2011 and August 2013, most of them from a swarm between December 4th and 12th, 2011. The sparser permanen...

A double-correlation method is introduced to locate tremor sources based on stacks of complex, doubly-correlated tremor records of multiple triplets of seismographs back projected to hypothetical source locations in a geographic grid. Peaks in the resulting stack of moduli are inferred source locations. The stack of the moduli is a robust measure o...

A 23 hour tremor burst was recorded on July 8-9th 2011 at the Katla subglacial volcano, one of the most active and hazardous volcanoes in Iceland. This was associated with deepening of cauldrons on the ice cap and a glacial flood that caused damage to infrastructure. Increased earthquake activity within the caldera started a few days before and las...

A 23 hour tremor burst was recorded on July 8-9th 2011 at the Katla subglacial volcano, one of the most active and hazardous volcanoes in Iceland. This was associated with deepening of cauldrons on the ice cap and a glacial flood that caused damage to infrastructure. Increased earthquake activity within the caldera started a few days before and las...

Earth processes in volcanic areas often produce complex seismic signals which lack a clear onset. For such signals one cannot use first-arrival picks to locate a source, as is commonly done for earthquake locations. Over the last decade inter-station cross correlation has become a popular approach for the analysis of seismic noise. In particular, t...

Relative relocation methods are commonly used to precisely relocate earthquake clusters consisting of similar waveforms. Repeating waveforms are often recorded at volcanoes, where, however, the crust structure is expected to contain strong heterogeneities and therefore the 1D velocity model assumption that is made in most location strategies is not...

Katla volcano is one of the most active and threatening volcanoes in Iceland. It is partly covered by Mýrdalsjökull glacier and the last explosive eruption to break the ice-surface occurred in 1918. The current repose time is the longest known in history. Increased seismicity and a tremor burst were recorded on July 8-9th 2011, associated with floo...

Located beneath Myrdalsjokull ice cap, Katla volcano is one of the most active and threatening volcanoes in Iceland, with at least 20 eruptions in the last 1100 years. The last phreatomagmatic eruption to break the ice-surface occurred in 1918 and signs of unrest have been detected since 1955, culminating in flooding from the ice cap in 1955, 1999...