Sapienza Research Calls - GEO10
PRINCIPAL INVESTIGATOR: Maurizio BATTAGLIA
TITLE: Modeling the evolution of volcanic processes in the Nevado del Ruiz volcano (Colombian Andes) by using Interferometric Synthetic Aperture Radar and continuous Global Positioning System constraints
FUNDING AGENCY: Sapienza – Piccoli Progetti Universitari
START DATE: Giugno 2020
END DATE: Giugno 2023
ABSTRACT:
Deformation signals recorded at volcanoes have long been used to investigate volcanic processing. Parameters such as location, depth, and volume change can be inferred from the ground displacements measured on the Earth¿s surface by applying inversion techniques. Deformation measurements at active volcanoes are usually made with continuous Global Positioning System (CGPS) stations, supplemented by Interferometric Synthetic Aperture Radar (InSAR) images. InSAR can image ground deformation over large areas at centimeter-scale resolution over time-scales of days to a few years, while CGPS can provide continuous information on three dimensional ground displacements at a network of key sites. Nevado del Ruiz volcano rises 5321 meters above sea level in the Colombian Andes. In November 1985, pyroclastic material fall from a modest explosive eruption led to the sudden melting of the volcano ice-cap, and the formation of a lahar that reached and destroyed the town of Armero and part of the town of Chinchina causing 25000 dead. After a decade of quiescence, in 2010 Nevado del Ruiz entered in the present period of unrest with a significant increase in seismicity, surface deformation and gas venting. We will investigate the interaction between the volcano magmatic system and local tectonics to explain the present volcanic unrest. Analysis of GPS displacements from 2010 to present, and InSAR from 2012 to 2015,
will allow to constrain the source of unrest and infer the local stress transfer controlling the subsurface magma and fluid flow. The analysis will be based on both analytical and numerical inversion of geodetic data. We will first employ analytical models to constrain the source of unrest. Then we will develop numerical Finite Element Method models to evaluate the influence of irregular geometries,
volcanic topography, heterogeneous material properties and various rheologies on the local stress transfer and the evolution of the volcanic unrest.
PRINCIPAL INVESTIGATOR: Elisa TINTI
TITLE: The role of shear fabric in controlling breakdown processes during laboratory events
FUNDING AGENCY: Progetti di Ricerca “Medi" anno 2020, Università La Sapienza, Roma, - n. protocollo RM120172A2EAC019
START DATE: Dicembre 2020
END DATE: Dicembre 2023
ABSTRACT:
Earthquakes represent a fundamentally challenging scientific problem. In the last decade the new geophysical discoveries have greatly improved our knowledge on how faults accommodate slip and on their ability to produce earthquakes. Geophysical and geodetic observations, source modeling and experiments suggest that faults are heterogeneous in their physical properties and temporal behavior, leading to variations and complexities in slip styles, friction, earthquake recurrence intervals and involved physical processes. The aim of this project is to study the effect of fault rock (in terms of its fabric) and strain localization in controlling traction evolution and slip velocity time histories during laboratory earthquakes. We will use a double-direct biaxial shear apparatus and different fault gouges, including heterogeneous minerals mixture as a proxy for real fault rocks, to study slip events at the laboratory scale. Measuring fine details of fault slip velocity time history, volumetric deformation and friction during many seismic cycles, coupled with an analysis of the microstructures, we want to get inferences on the physical processes at play. The slip velocity function contains the dynamic information needed to characterize the evolution of stress during breakdown process and it is usually imposed a-priori during earthquakes kinematic modeling on natural faults due to the limited resolution of recorded data. With our project we want to study the spontaneous slip velocity function recorded during laboratory events and to relate its temporal evolution with shear fabric. Moreover, with the use of different fault gauges we want to get inferences on how the energy is differently absorbed on the slipping surfaces with significant insights for understanding of earthquake process. Finally, the multidisciplinary geophysical team recently assembled in Sapienza will be a perfect environment to train PhD and Post-docs researchers interested in earthquake mechanics.