Luca De Siena

Johannes Gutenberg-Universität Mainz | JGU · Institute for Geosciences

Sedimentary basins in collisional settings result from interactions within and between lithospheric plates and sublithospheric mantle. Imaging their structure brings fundamental constraints to both the extraction of hydrocarbon or geothermal resources and seismic hazard analyses, especially in seismogenic areas affected by fluid percolation. Seismi...

Peak delays of Acoustic Emission data from rock deformation laboratory experiments are sensitive to both sample heterogeneities and deformation-induced impedance contrasts inside the sample. However, the relative importance of stochastic heterogeneity and discontinuities is uncertain, as is the relationship between peak delays and applied stress an...

Modelling the response of seismic wavefields to sharp lateral variations in crustal discontinuities is essential for seismic tomography application and path effects correction in earthquake source characterization. This is particularly relevant when wavefields cross back-arc oceanic basins, i.e. mixed continental-oceanic settings. High-frequency (>...

Seismic waves produced by stressed and deforming rocks lose coherence when they cross regions of high heterogeneity. The delay in the arrival of maximum seismic energy amplitude (peak delay), an essential attribute to model earthquake source characteristics, is increasingly used to map complex crustal geology, heterogeneous reservoirs and fault net...

Plain Language Summary Deception Island is the gateway for tourists to Antarctica and a laboratory to understand ice‐capped volcanoes and their eruptions. While the Island has been the target of many geophysical studies, no clear tomographic model shows how deep eruptive pathways of its last eruptions have reached the surface in the 1960s and 1970s...

Plain Language Summary Pores control the non‐elastic behavior and, in general, the petrophysical and mechanical properties of rocks. Such properties are essential to assess potential resources such as aquifers and reservoirs or hazards posed by earthquakes, volcanoes, and constructions. The factors controlling the elasticity of rocks are texture, p...

Plain Language Summary The interplay between magmatic and tectonic forces during rifting is still debated. While they are a key component of rift development, the complex structures of rifts and melt storage systems scatter and absorb seismic waves passing through them: in turn, this deteriorates the quality of the subsurface images we obtain from...

The Amatrice–Visso–Norcia seismic sequence struck Central Italy across the Apenninic normal fault system in 2016. Fluids likely triggered the sequence and reduced the stability of the fault network following the first earthquake (Amatrice, Mw 6.0), with their migration nucleating the Visso (Mw 5.9) and Norcia (Mw 6.5) mainshocks. However, both spat...

Modelling the response of seismic wavefields to sharp lateral variations in crustal discontinuities is essential for the application of seismic tomography and the correction of path effects in earthquake source characterization. Researchers generally focus on travel times and amplitudes of a limited number of phases, simplifying the underlying phys...

Active seismic experiments allow reconstructing the subsurface structure of volcanoes with unprecedented resolution and are vital to improve the interpretation of volcanic processes. They require a quality assessment for thousands of seismic waveforms recorded at hundreds of stations in the shortest amount of time. However, the processing necessary...

Imaging of fluid pathways is crucial to characterize processes taking place in hydrothermal systems, a primary cause of volcanic unrest and associated hazards. The joint imaging of seismic absorption and scattering is an efficient instrument to map fluid flow at crustal scale, and specifically in volcanoes; however, this technique has so far been a...

We present a comprehensive review of seismic and gravity observations and tomographic models produced over the past four decades in order to understand the structure of the crust beneath the Campi Flegrei caldera. We describe the main lithological and structural discontinuities defined through these observations, illustrate their geophysical respon...

Ambient noise polarizes inside fault zones, yet the spatial and temporal resolution of polarized noise on gas-bearing fluids migrating through stressed volcanic systems is unknown. Here we show that high polarization marks a transfer structure connecting the deforming centre of the caldera to open hydrothermal vents and extensional caldera-bounding...

Modelling regional-scale attenuation of seismic waves at ∼1 Hz is challenging, especially when these waves propagate across both continental and oceanic crust. Recent developments in seismic imaging and modelling have provided us with the computational tools necessary to reconstruct these mixed settings using deterministic (coherent) and stochastic...

Seismic attenuation measurements, especially those obtained from coda decay analysis, are becoming a key data source for the characterization of the heterogeneous Earth due to their sensitivity to small-scale heterogeneities. However, the relation between the scattering attenuation measured from coda waves and physical rock properties is still uncl...

Identifying deformation and pre-failure mechanisms preceding faulting is key for fault mechanics and for interpreting precursors to fault rupture. This study presents the results of a new and robust derivation of first motion polarity focal mechanism solutions (FMS) applied to acoustic emission (AE). FMS are solved using a least squares minimizatio...

Ambient noise polarizes inside low-velocity fault zones, yet the spatial and temporal resolution of polarized noise on gas-bearing fluids migrating through stressed volcanic systems is unknown. Pressurized fluids increase stress and lead to volcanic earthquakes; imaging their location in real time would be a giant leap toward forecasting eruptions...

How well can geophysical methods image magmatic systems? Geophysical methods are commonly used to image magmatic systems; however, synthetic studies which give insights into the resolution of such methods and their interpretational scope are rare. Gravity anomalies, magnetotelluric, seismological and geodynamical modelling all have a different sens...

Identifying deformation and pre-failure mechanisms preceding faulting is key for fault mechanics and for interpreting precursors to fault rupture. This study presents the results of a new and robust derivation of first motion polarity focal mechanism solutions (FMS) applied to Acoustic Emission (AE). FMS are solved using a least squares minimisatio...

The Pollino range is a region of slow deformation where earthquakes generally nucleate on low-angle normal faults. Recent studies have mapped fault structures and identified fluid-related dynamics responsible for historical and recent seismicity in the area. Here, we apply the coda-normalization method at multiple frequencies and scales to image th...

Modeling seismicity at volcanoes remains challenging as the processes that control seismic energy release due to fluid transport, heat flow, and rock deformation are firmly coupled in complex geological media. Here, we couple fluid‐flow and mechanical (deformation) simulators (TOUGHREACT–FLAC3D) to reproduce fluid‐induced seismicity at Campi Flegre...

We report a new method using a Time Delay Neural Network to transform Acoustic Emission (AE) waveforms into timeseries of instantaneous frequency content and permutation entropy. This permits periods of noise to be distinguished from signals. The model is trained in sequential batches, using an automated process that steadily improves signal recogn...

Mount St. Helens is a stratovolcano of the Cascadia volcanic arc well known worldwide for its volcanic collapse and eruption in 1980, which caused considerable destruction and changed the geomorphology of the volcano and of a considerable portion of its surroundings. This paper presents a geomorphology and surface-geology map of both the wider Moun...

High-resolution seismic imaging enables the reconstruction of ascending paths of magma and fluids, shallow molten accumulation and flank collapse areas, all crucial information for developing an efficient eruption forecasting strategy. Here, the Marching Cubes algorithm (MC - generally applied to medical visualization and three-dimensional (3D) mod...

Southeast Asia lies within one of the most complex tectonic settings on Earth and exhibits a range of features, including strongly curved subduction zones, arc-continent collision, and slab break-off, which are not well understood. To help gain insight into mantle structure and processes beneath this region, we perform an inversion for variations i...

In volcanoes, topography, shallow heterogeneity and even shallow morphology can substantially modify seismic coda signals. Coda waves are an essential tool to monitor eruption dynamics and model volcanic structures jointly and independently from velocity anomalies: it is thus fundamental to test their spatial sensitivity to seismic path effects. He...

Acoustic Emission (AE) refer to the release of energy that occurs due to inelastic deformation of media at the laboratory scale. Analogous to seismic data, they provide a crucial window into the analyses of energy propagation at a scale that is relatively easy to handle. In this thesis, the fracturing processes in the lead up to dynamic failure of...

Seafloor methane seepage is a significant source of carbon in the marine environment. The processes and temporal patterns of seafloor methane seepage over multi-million-year time scales are still poorly understood. The microbial oxidation of methane can store carbon in sediments through precipitation of carbonate minerals, thus providing a record o...

Methane seepage at the seafloor is a source of carbon in the marine environment and has long been recognized as an important window into the deep geo-, hydro-, and bio-spheres. However, the processes and temporal patterns of natural methane emission over multi-million-year time scales are still poorly understood. The microbially-mediated methane ox...

The repeated deformations and seismic unrests at Campi Flegrei caldera (southern Italy) have been identified due to a fluid injection source in volcano active area. We investigated the role of hot water injection in the seismic unrests of 1982-1984 with a view to gaining insights into the caldera’s dynamics, by applying coupled TOUGHREACT-FLAC 3D s...

In recent years, attenuation has been used as a marker for source and dynamic Earth processes due to its higher sensitivity to small variations of lithospheric properties compared to seismic velocity. From seismic hazard analysis to oil and gas exploration and rock physics, many fields need a better reconstruction of energy absorption, a constituen...

Regions of slow strain often produce swarm-like sequences, characterized by the lack of a clear mainshock- aftershock pattern. The comprehension of their underlying physical mechanisms is challenging and still debated. We used seismic recordings from the last Pollino swarm (2010–2014) and nearby to separate and map seismic scattering (from P peak-d...

Observations from satellites provide high-resolution images of ground deformation allowing to infer deformation sources by developing advanced modeling of magma ascent and intrusion processes. Nevertheless, such models can be strongly biased without a precise model of the internal structure of the volcano. In this study, we jointly exploited two in...

Insights into the enucleation and propagation of fractures is provided through identification of Focal Mechanisms of Acoustic Emission data. Temporal variations of collapsing (C-type), shearing (S-type) and tensile (T-type) fracturing highlight underlying processes in fracture propagation. However, results are strongly dependent on the quality of...

The delay in the maximum amplitude arrival of seismic energy (peak delay) is an important attribute to map complex geology, fluid reservoirs, and faulting in the lithosphere. We measured and mapped the parameter in the frequency range 50 to 800 KHz using Acoustic Emission data recorded during triaxial deformation experiments of Westerly Granite and...

Coda-wave attenuation imaging has risen as a state-of-the-art technique to depict volcanic structures using their dispersion effects. The 1982-84 seismic and deformation unrest at Campi Flegrei caldera (Italy) is a unique exam­ple of non-eruptive volcanic activity in a structured caldera. Here, we propose the first application of 30 coda­attenuatio...

The southeast (SE) Asia - Australia collision zone is one of the most tectonically active and seismogenic regions in the world. Here, we present new 3-D P- and S-wave velocity models of the crust and upper mantle by applying regional earthquake travel-time tomography to global catalogue data. We first re-locate earthquakes provided by the standard...

Aim of the work Regions of slow strain such as the Pollino range (Southern Italy) produce earthquake swarms without a clear mainshock-aftershock sequence, often characterized by migration of the sources along complex fault patterns. Our aim is to use seismic recordings from the 2010-2014 Pollino sequence to separate and map at 4 different frequency...

The southeast (SE) Asia - Australia collision zone is one of the most tectonically active and seismogenic regions in the world. Here, we present new 3-D P- and S-wave velocity models of the crust and upper mantle by applying regional earthquake travel-time tomography to global catalogue data. We first re-locate earthquakes provided by the standard...

Acoustic Emissions (AE), the laboratory analogue to tectonic seismic events, recorded during conventional triaxial deformation tests allow for an unprecedented amount of information on the evolution of fractured media within a controlled environment. This study presents the results of a new, robust, derivation of first motions calculated from AE-de...

Acoustic Emissions (AE), the laboratory analogue to tectonic seismic events, recorded during conventional triaxial deformation tests allow for an unprecedented amount of information on the evolution of fractured media within a controlled environment. This study presents the results of a new, robust, derivation of first motions calculated from AE-de...

Acoustic Emissions (AE), the laboratory analogue to tectonic seismic events, recorded during conventional triaxial deformation tests allow for an unprecedented amount of information on the evolution of fractured media within a controlled environment. This study presents the results of a new, robust, derivation of first motions calculated from AE-de...

Acoustic Emissions (AE), the laboratory analogue to tectonic seismic events, recorded during conventional triaxial deformation tests allow for an unprecedented amount of information on the evolution of fractured media within a controlled environment. This study presents the results of a new, robust, derivation of first motions calculated from AE-de...

Earthquakes at Campi Flegrei have been low magnitude and sparse since 1985, denying onshore monitoring observations of their usual source for structural constraint: seismic tomography. Here we used continuous seismic records from 2011–2013 to reconstruct period-dependent Rayleigh wave group velocity maps of the volcano. The Neapolitan Yellow Tuff r...

Seismic coda measurements retrieve parameters linked to the physical characteristics of rock volumes illuminated by high frequency scattered waves. Space weighting functions (SWF) and kernels are different tools that model the spatial sensitivity of coda envelopes to scattering and absorption anomalies in these rock matrices, allowing coda-wave att...

Volcanic activity can have a notable impact on glacier behaviour (dimensions and dynamics). This is evident from the palaeo-record, but is often difficult to observe for modern glaciers. However, documenting and, if possible, quantifying volcanic impacts on modern glaciers is important if we are to predict their future behaviour (including crucial...

PICO presentation of the VolGIS' first version prototype.

Discriminating the effects of scattering attenuation caused by structural properties and the intrinsic attenuation caused by media properties from the propagation of seismic energy has been a long standing problem in geo-physical imaging. Rock deformation laboratory experiments provide an opportunity to test different tomographic methods, initially...

Imaging the interior of a volcano is crucial step to model its dynamics and develop an efficient eruption forecasting strategy. High-resolution seismic image models of the interior of the volcanoes, usually based on tomographic methods, make possible to image the shape and locate possible lava ascending paths, shallow magma chambers and areas of fl...

Villarrica volcano is the most active and hazardous volcano in the southern volcanic zone in the Chilean Andes. Most of the volcanic edifices in the Southern Volcanic Zone are emplaced along the arc-parallel 1000-km long Liquiñe-Ofqui Fault Zone (LOFZ). For Villarrica volcano, the emplacement falls at the intersection with the NW striking Villarric...

VolGIS is a new volcano-oriented Geographic Information System that makes possible to model and visualize different volcano-related available data in a user-friendly high-resolution visualization environment. The goal of this project is to create an open-source freeware platform where the user can apply a set of analysis tools to a specific volcani...

Discriminating the effects of scattering attenuation caused by structural properties and the intrinsic attenuation caused by media properties from the propagation of seismic energy has been a long standing problem in geophysical imaging. Rock deformation laboratory experiments provide an opportunity to test different tomographic methods, initially...

Earthquakes at Campi Flegrei have been low-magnitude and sparse for more than thirty years, denying onshore monitoring observations of their usual source for structural constraint: seismic tomography. Here, we used ambient seismic noise recorded between 2011 and 2013 to reconstruct period-dependent Rayleigh-wave velocity maps of caldera-wide struct...

We present a P-wave scattering image of the volcanic structures under Tenerife Island using the autocorrelation functions of P-wave vertical velocity fluctuations. We have applied a cluster analysis to total quality factor attenuation (\( {Q}_t^{-1} \)) and scattering quality factor attenuation (\( {Q}_{PSc}^{-1} \)) images to interpret the structu...

We present an expanded approach of the diffusive approximation to map strongly scattering geological structures in volcanic environments using seismic coda intensities and a diffusive approximation. Seismic data from a remarkably consistent hydrothermal source of Long-Period (LP) earthquakes, that was active during the late 2004 portion of the 2004...

In recent years, 3D and 4D seismic tomography have unraveled medium changes during the seismic cycle or before eruptive events. As our resolving power increases, however, complex structures increasingly affect images. Being able to interpret and understand these features requires a multi-discipline approach combining different methods, each sensiti...

In recent years, 3D and 4D seismic tomography have unraveled medium changes during the seismic cycle or before eruptive events. As our resolving power increases, however, complex structures increasingly affect images. Being able to interpret and understand these features requires a multi-discipline approach combining different methods, each sensiti...

The inter-arrival times of the post 2000 seismicity at Campi Flegrei caldera are statistically distributed into different populations. The low inter-arrival times population represents swarm events, while the high inter-arrival times population marks background seismicity. Here, we show that the background seismicity is increasing at the same rate...

The project aims to solve the problem of locating/tracking gas and fluid movements in the subsurface and image sub-basaltic and sub-intrusive structures in the Rockall Basin. To do so, we use the non-standard imaging techniques of scattering and attenuation tomography. Ultimately, we aim to relate the imaging results with the lithology of the sampl...

The timely estimation of short- and long-term volcanic hazard relies on the availability of detailed 3D geophysical images of volcanic structures. High-resolution seismic models of the absorbing uppermost conduit systems and highly-heterogeneous shallowest volcanic layers, while particularly challenging to obtain, provide important data to locate f...

Despite their importance for eruption forecasting the causes of seismic rupture processes during caldera unrest are still poorly reconstructed from seismic images. Seismic source locations and waveform attenuation analyses of earthquakes in the Campi Flegrei area (Southern Italy) during the 1983–1984 unrest have revealed a 4–4.5 km deep NW-SE strik...