Person:
Mattesini, Maurizio

First Name

Maurizio

Last Name

Mattesini

URI

https://hdl.handle.net/20.500.14352/75167

Affiliation

Universidad Complutense de Madrid

Faculty / Institute

Ciencias Físicas

Department

Física de la Tierra y Astrofísica

Area

Física de la Tierra

Identifiers

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Now showing 1 - 10 of 13

From an atomistic study of olivine under pressure to the understanding of the macroscopic energy release in earthquakes
(Geosystems and Geoenvironment, 2023) López Sánchez, Carolina; Mattesini, Maurizio; Buforn Peiró, Vicenta María Elisa; Udías Vallina, Agustín; Serna Valdés, Jaime de la; Talavera, Hernando; Pro, Carmen
We present a multi-disciplinary study of the rupture process of deep- and intermediate-depth earthquakes in the subducting slab that develops beneath the Peruvian-Brazilian region. This contemplates the understanding of the atomistic fracture mechanism in an olivine model, its energetics budget, and the bridging of these results to the available seismic observables. A theoretical description of the stress-strain curves for the subducting material is initially provided as a key element to discern whether the rupture mechanism changes with depth or not. To this purpose, atomistic modelling was carried out through ab initio techniques for the forsterite olivine at different pressure ranges. The achieved stress-strain curves were compared to the average moment-scaled functions obtained for 43 intermediate (50 km < h < 200 km) and very deep earthquakes (500 km < h < 700 km) at the Peruvian-Brazilian subduction zone. It is found that at both depths operate a common atomistic rupture mechanism that is based on the gliding of the {001} crystal planes. Although the velocity of stress release changes with depth, this finding helps to clarify the controversial rupture process for very deep earthquakes at subduction zones. Likewise, efforts were directed to quantify the total amount of energy freed during an earthquake. Test calculations were carried out for several deep earthquakes providing rupture energy of six orders of magnitudes larger than the observable radiated seismic energy. This indicates that there might be space for redefining the commonly accepted order of magnitude for the seismic efficiency coefficient.
Candy wrapper for the Earth's inner core
(Scientific reports, 2013) Mattesini, Maurizio; Belonoshko, A.B.; Tkalčić, H.; Buforn Peiró, Vicenta María Elisa; Udías Vallina, Agustín; Ahuja, R.
Recent global expansion of seismic data motivated a number of seismological studies of the Earth’s inner core that proposed the existence of increasingly complex structure and anisotropy. In the meantime, new hypotheses of dynamic mechanisms have been put forward to interpret seismological results. Here, the nature of hemispherical dichotomy and anisotropy is re-investigated by bridging the observations of PKP(bc-df) differential travel-times with the iron bcc/hcp elastic properties computed from first-principles methods.The Candy Wrapper velocity model introduced here accounts for a dynamic picture of the inner core (i.e., the eastward drift of material), where different iron crystal shapes can be stabilized at the two hemispheres. We show that seismological data are best explained by a rather complicated, mosaic-like, structure of the inner core, where well-separated patches of different iron crystals compose the anisotropic western hemispherical region, and a conglomerate of almost indistinguishable iron phases builds-up the weakly anisotropic eastern side.
Magnetic anisotropy in Cr_(2)GeC investigated by X-ray magnetic circular dichroism and ab initio calculations
(Journal of magnetism and magnetic materials, 2020) Magnuson, Martin; Mattesini, Maurizio
The magnetism in the inherently nanolaminated ternary MAX-phase Cr_(2)GeC is investigated by element-selective, polarization and temperature-dependent, soft X-ray absorption spectroscopy and X-ray magnetic circular dichroism. The measurements indicate an antiferro-magnetic Cr-Cr coupling along the c-axis of the hexagonal structure modulated by a ferromagnetic ordering in the nanolaminated ab-basal planes. The weak chromium magnetic moments are an order of magnitude stronger in the nanolaminated planes than along the vertical axis. Theoretically, a small but notable, non-spin-collinear component explains the existence of a non-perfect spin compensation along the c-axis. As shown in this work, this spin distortion generates an overall residual spin moment inside the unit cell resembling that of a ferri-magnet. Due to the different competing magnetic interactions, electron correlations and temperature effects both need to be considered to achieve a correct theoretical description of the Cr_(2)GeC magnetic properties.
Four Years of Earthquake Early Warning in Southern Iberia: 2016-2019
(Frontiers in Earth Science, 2021) Carranza, Marta; Mattesini, Maurizio; Buforn Peiró, Vicenta María Elisa; Zollo, Aldo; Torrego, Irene
The performance of an earthquake early warning system (EEWS) for southern Iberia during the period of 2016-2019 is analyzed. The software PRESTo (PRobabilistic and Evolutionary early warning SysTem; the University of Naples Federico II, Italy) operating at the Universidad Complutense de Madrid has detected 728 events (2 < M-w < 6.3), with 680 earthquakes occurring in southern Iberia. Differences between the EEWS origin time and epicenter and those of the Instituto Geografico Nacional (IGN) catalog are less than 2 s and 20 km, respectively, for 70% of the detected earthquakes. The main differences correspond to the EEWS magnitude that is underestimated for earthquakes that occurred at the west of the Gibraltar Strait (M-w differences larger than 0.3 for 70%). To solve this problem, several relationships have been tested, and a modification to those that currently use PRESTo is proposed. Other improvements, such as to densify the network or to use 3D Earth models, are proposed to decrease the time needed to issue the alert and avoid the false alerts (19 events over a total of 728 events). The EEWS has estimated the depth for 680 events and compared to those from the IGN (491 events). The performance of PRESTo during the 2020-2021 Granada swarm is analyzed. The hypocentral locations for the three largest earthquakes are close to those from the IGN (differences from 1 to 7 km for the epicenter and 0 s for the time origin), although there are some differences in their magnitude estimations that varies from 0.2 to 0.5. The PRESTo first times are 17, 25, and 41 s after the origin time. This study shows that the actual PRESTo EEWS configured for the southern Iberia may generate effective warnings despite the low seismicity rate in this region. To decrease the warning time, the geometry and density of the seismic network must be improved together with the use of 3D Earth models and on-site system approaches.
Strong, multi-scale heterogeneity in earth's lowermost mantle
(Scientific reports, 2015) Tkalčić, Hrvoje; Young, Mallory; Muir, Jack B.; Davies, D. Rhodri; Mattesini, Maurizio
The core mantle boundary (CMB) separates Earth's liquid iron outer core from the solid but slowly convecting mantle. The detailed structure and dynamics of the mantle within similar to 300 km of this interface remain enigmatic: it is a complex region, which exhibits thermal, compositional and phase-related heterogeneity, isolated pockets of partial melt and strong variations in seismic velocity and anisotropy. Nonetheless, characterising the structure of this region is crucial to a better understanding of the mantle's thermo-chemical evolution and the nature of core-mantle interactions. In this study, we examine the heterogeneity spectrum from a recent P-wave tomographic model, which is based upon trans-dimensional and hierarchical Bayesian imaging. Our tomographic technique avoids explicit model parameterization, smoothing and damping. Spectral analyses reveal a multi-scale wavelength content and a power of heterogeneity that is three times larger than previous estimates. Inter alia, the resulting heterogeneity spectrum gives a more complete picture of the lowermost mantle and provides a bridge between the long-wavelength features obtained in global S-wave models and the short-scale dimensions of seismic scatterers. The evidence that we present for strong, multi-scale lowermost mantle heterogeneity has important implications for the nature of lower mantle dynamics and prescribes complex boundary conditions for Earth's geodynamo.
Intermediate-depth earthquakes in southern Spain and Alboran Sea
(Tectonophysics, 2022) López Sánchez, Carolina; Buforn Peiró, Vicenta María Elisa; Cesca, Simone; Lozano, Lucía; Sanz de Galdeano, Carlos; Mattesini, Maurizio; Udías Vallina, Agustín; Cantavella, Juan Vicente
A striking feature of the seismicity in the Ibero-Maghrebian region is a narrow band of intermediate-depth earthquakes (50 < h < 100 km) beneath the western part of the Alboran Sea, with epicenters following a NNE-SSW alignment. The origin and characteristics of this seismicity are debated, and an accurate analysis of this seismic scenario is provided despite the low to moderate magnitude of these earthquakes. In this study, we collect 20 years of seismic data from permanent and temporary installations and reprocess these data with the aid of advanced seismological techniques, including non-linear probabilistic relocation with a 3D-Earth velocity model and a probabilistic moment tensor inversion scheme, to shed new light on intermediate-depth seismicity in Southern Spain and the Alboran Sea. We relocated 238 intermediate-depth earthquakes (M >= 3) using a nonlinear probabilistic approach and a recent regional 3D tomography lithospheric velocity model for the Alboran-Betic Rif Zone. Maximum likelihood hypocenters confirm the NNE-SSW distribution in a depth range between 50 and 100 km, depicting three clusters of epicenters with a seismic gap that may be correlate to the boundary between the sunken slabs of the Iberian and African plates around Gibraltar. We simultaneously determined the focal mechanisms of 25 mb > 3.9 earthquakes using P-waves and moment tensors by fitting body-wave amplitude spectra and waveform cross-correlations. We performed an accurate resolution study by repeating the inversion using different 1-D velocity models. The results show predominant horizontal T axes with a rotation on the direction from NE-SW in southern Spain to E-W near the African coast. The distribution of intermediate-depth earthquakes and their source geometries provide new evidence of the seismotectonic complexity of the region, which is possibly controlled by the stopping or slowing down of subduction.
Chemical bonding and electronic-structure in MAX phases as viewed by Xray spectroscopy and density functional theory
(Thin solid films, 2017) Magnuson, Martin; Mattesini, Maurizio
This is a critical review of MAX-phase carbides and nitrides from an electronic-structure and chemical bonding perspective. This large group of nanolaminated materials is of great scientific and technological interest and exhibit a combination of metallic and ceramic features. These properties are related to the special crystal structure and bonding characteristics with alternating strong M-C bonds in high-density MC slabs, and relatively weak M-A bonds between the slabs. Here, we review the trend and relationship between the chemical bonding, conductivity, elastic and magnetic properties of the MAX phases in comparison to the parent binary MX compounds with the underlying electronic structure probed by polarized X-ray spectroscopy. Spectroscopic studies constitute important tests of the results of state-of-the-art electronic structure density functional theory that is extensively discussed and are generally consistent. By replacing the elements on the M, A, or X-sites in the crystal structure, the corresponding changes in the conductivity, elasticity, magnetism and other materials properties makes it possible to tailor the characteristics of this class of materials by controlling the strengths of their chemical bonds.
Low viscosity of the Earth’s inner core
(Nature communications, 2019) Belonoshko, Anatoly B.; Fu, Jie; Bryk, Taras; Simak, Sergei I.; Mattesini, Maurizio
The Earth’s solid inner core is a highly attenuating medium. It consists mainly of iron. The high attenuation of sound wave propagation in the inner core is at odds with the widely accepted paradigm of hexagonal close-packed phase stability under inner core conditions, because sound waves propagate through the hexagonal iron without energy dissipation. Here we show by first-principles molecular dynamics that the body-centered cubic phase of iron, recently demonstrated to be thermodynamically stable under the inner core conditions, is considerably less elastic than the hexagonal phase. Being a crystalline phase, the bodycentered cubic phase of iron possesses the viscosity close to that of a liquid iron. The high attenuation of sound in the inner core is due to the unique diffusion characteristic of the body-centered cubic phase. The low viscosity of iron in the inner core enables the convection and resolves a number of controversies.
Project number: PIMCD400/23-24
De la física a la biología. Un viaje de ida y vuelta
(2024) Mazo Torres, Juan José; Dinis Vizcaíno, Luis Ignacio; Mattesini, Maurizio; Zarco Moreno, Manuel; Valencia Cárdenas, Víctor Manuel; Mazo Torres, Juan José
Imaging the top of the Earth’s inner core: a present‑day flow model
(Scientific Reports, 2024) Tkalčić, Hrvoje; Belonoshko, Anatoly B.; Muir, Jack B.; Mattesini, Maurizio; Moresi, Louis; Waszek, Lauren
Despite considerable progress in seismology, mineral physics, geodynamics, paleomagnetism, and mathematical geophysics, Earth’s inner core structure and evolution remain enigmatic. One of the most significant issues is its thermal history and the current thermal state. Several hypotheses involving a thermally-convecting inner core have been proposed: a simple, high-viscosity, translational mode, or a classical, lower-viscosity, plume-style convection. Here, we use state-of-the-art seismic imaging to probe the outermost shell of the inner core for its isotropic compressional speed and compare it with recently developed attenuation maps. The pattern emerging in the resulting tomograms is interpreted with recent data on the viscosity of iron as the inner core surface manifestation of a thermally-driven flow, with a positive correlation among compressional speed and attenuation and temperature. Although the outer-core convection controls the heat flux across the inner core boundary, the internally driven inner-core convection is a plausible model that explains a range of observations for the inner core, including distinct anisotropy in the innermost inner core.