scholarly journals 3D Numerical Simulations of Non-Volcanic CO2 Degassing in Active Fault Zones Based on Geophysical Surveys

2021 ◽  
Author(s):  
R. Di Maio ◽  
R. Salone ◽  
C. De Paola ◽  
E. Piegari ◽  
S. Vitale
Keyword(s):  
Numerical Simulations ◽  
Active Fault ◽  
Integrated Approach ◽  
Test Site ◽  
Fault Zones ◽  
Fault System ◽  
Geophysical Surveys ◽  
Passive Seismic ◽  
Petrophysical Model ◽  
Source Models

Abstract An integrated approach that combines geophysical surveys and numerical simulations is proposed to study the processes that govern the fluid flow along active fault zones. It is based on the reconstruction of the architecture of the investigated fault system, as well as the identification of possible paths for fluid migration, according to the distribution of geophysical parameters retrieved by multi-methodological geophysical prospecting. The aim is to establish, thanks to constraints deriving from different types of data (e.g., geological, geochemical and/or hydrogeological data), an accurate 3D petrophysical model of the survey area to be used for simulating, by numerical modelling, the physical processes likely taking place in the imaged system and its temporal evolution. The effectiveness of the proposed approach is tested in an active fault zone in the Matese Mts (southern Italy), where recent, accurate geochemical measurements have registered very high anomalous values of non-volcanic natural emissions of CO2. In particular, a multi-methodological geophysical survey, consisting of electrical resistivity tomography, self-potential and passive seismic measurements, integrated with geological data, was chosen to define the 3D petrophysical model of the investigated system and to identify possible source geometries. Three different scenarios were assumed corresponding to three different CO2 source models. The one that hypothesizes a source located along the fault plane at the depth of the carbonate basement was found to be the best candidate to represent the test site. Indeed, the performed numerical simulations provide CO2 flow estimates comparable with the values observed in the investigated area. These findings are promising for gas hazards, as they suggest that numerical simulations of different CO2 degassing scenarios could forecast possible critical variations in the amount of CO2 emitted near the fault.

Passive seismic velocity monitoring of natural faults: The FaultScan project

2020 ◽  
Author(s):  
Florent Brenguier ◽  
Aurelien Mordret ◽  
Yehuda Ben-Zion ◽  
Frank Vernon ◽  
Pierre Boué ◽  
...  
Keyword(s):  
Seismic Velocity ◽  
Fault Zones ◽  
Body Waves ◽  
Fault System ◽  
Seismic Arrays ◽  
San Jacinto Fault ◽  
Highway Network ◽  
Seismic Velocity Changes ◽  
Passive Seismic ◽  
Velocity Changes

<p>Laboratory experiments report that detectable seismic velocity changes should occur in the vicinity of fault zones prior to earthquakes. However, operating permanent active seismic sources to monitor natural faults at seismogenic depth has been nearly impossible to achieve. The FaultScan project (Univ. Grenoble Alpes, Univ. Cal. San Diego, Univ. South. Cal.) aims at leveraging permanent cultural sources of ambient seismic noise to continuously probe fault zones at a few kilometers depth with seismic interferometry. Results of an exploratory seismic experiment in Southern California demonstrate that correlations of train-generated seismic signals allow daily reconstruction of direct P body-waves probing the San Jacinto Fault down to 4 km depth. In order to study long-term earthquake preparation processes we will monitor the San Jacinto Fault using such approach for at least two years by deploying dense seismic arrays in the San Jacinto Fault region. The outcome of this project may facilitate monitoring the entire San Andreas Fault system using the railway and highway network of California. We acknowledge support from the European Research Council under grant No.~817803, FAULTSCAN.</p>

Estimation of Carbon Dioxide emissions along an active fault by using geoelectrical measurements

2020 ◽  
Author(s):  
Ester Piegari ◽  
Rosa Di Maio ◽  
Rosanna Salone ◽  
Claudio De Paola
Keyword(s):  
Carbon Dioxide ◽  
Seismic Data ◽  
Carbon Dioxide Emissions ◽  
Active Fault ◽  
Damage Zone ◽  
Thick Layer ◽  
Integrated Approach ◽  
Upward Migration ◽  
Passive Seismic ◽  
Zone Characteristic

<p>In the last twenty years, a growing interest is noticed in quantifying non-volcanic degassing, which could represent a significant input of CO<sub>2</sub> into the atmosphere. Large emissions of non-volcanic carbon dioxide usually take place in seismically active zones, where the existence of a positive spatial correlation between gas discharges and extensional tectonic regimes has been confirmed by seismic data. Extensional stress plays a key role in creating pathways for the rising of gases at micro- and macro-scales, increasing the rock permeability and connecting the deep crust to the earth surface. Geoelectrical investigations, which are very sensitive to permeability changes, provide accurate volumetric reconstructions of the physical properties of the rocks and, therefore, are fundamental not only for the definition of the seismic-active zone geometry, but also for understanding the processes that govern the flow of fluids along the damage zone. In this framework, we present the results of an integrated approach where geoelectrical and passive seismic data are used to construct a 3D geological model, whose simulated temporal evolution allowed the estimation of CO<sub>2</sub> flux along an active fault in the area of Matese Ridge (Southern Apennines, Italy). By varying the geometry of the source system and the permeability values of the damage zone, characteristic times for the upward migration of CO<sub>2</sub> through a thick layer of silts and clays have been estimated and CO<sub>2</sub> fluxes comparable with the observed values in the investigated area have been predicted. These findings are promising for gas hazard, as they suggest that numerical simulations of different CO<sub>2</sub> degassing scenarios could forecast possible critical variations in the amount of CO<sub>2</sub> emitted near the fault.</p>

scholarly journals Assessment of active fault zones by soil CO2 flux measurements in the Yangsan fault system, South Korea

2021 ◽  
Author(s):  
Jungpyo Hong ◽  
Heejun Kim ◽  
Hyunwoo Lee ◽  
Wonhee Lee ◽  
Jeongyeon Yu ◽  
...  
Keyword(s):  
South Korea ◽  
Active Fault ◽  
Co2 Flux ◽  
Fault Zones ◽  
Fault System ◽  
Soil Co2 ◽  
Soil Co2 Flux ◽  
Flux Measurements ◽  
Yangsan Fault ◽  
Yangsan Fault System

scholarly journals The Role of Faults in Groundwater Circulation before and after Seismic Events: Insights from Tracers, Water Isotopes and Geochemistry

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1499
Author(s):  
Davide Fronzi ◽  
Francesco Mirabella ◽  
Carlo Cardellini ◽  
Stefano Caliro ◽  
Stefano Palpacelli ◽  
...  
Keyword(s):  
Preferential Flow ◽  
Central Italy ◽  
Tracer Tests ◽  
Integrated Approach ◽  
Fault System ◽  
Tectonic Structures ◽  
Fault Systems ◽  
Isotopic Analyses ◽  
Before And After

The interaction between fluids and tectonic structures such as fault systems is a much-discussed issue. Many scientific works are aimed at understanding what the role of fault systems in the displacement of deep fluids is, by investigating the interaction between the upper mantle, the lower crustal portion and the upraising of gasses carried by liquids. Many other scientific works try to explore the interaction between the recharge processes, i.e., precipitation, and the fault zones, aiming to recognize the function of the abovementioned structures and their capability to direct groundwater flow towards preferential drainage areas. Understanding the role of faults in the recharge processes of punctual and linear springs, meant as gaining streams, is a key point in hydrogeology, as it is known that faults can act either as flow barriers or as preferential flow paths. In this work an investigation of a fault system located in the Nera River catchment (Italy), based on geo-structural investigations, tracer tests, geochemical and isotopic recharge modelling, allows to identify the role of the normal fault system before and after the 2016–2017 central Italy seismic sequence (Mmax = 6.5). The outcome was achieved by an integrated approach consisting of a structural geology field work, combined with GIS-based analysis, and of a hydrogeological investigation based on artificial tracer tests and geochemical and isotopic analyses.

scholarly journals Trenching study on the Tonoda Fault of the Mitoke Active Fault System at Sekibayashi, Kyoto Prefecture, Southwest Japan

2000 ◽  
Vol 109 (1) ◽  
pp. 73-86
Author(s):  
Yoshihiro UEMURA ◽  
Atsumasa OKADA ◽  
Heitarou KANEDA ◽  
Daisaku KAWABATA ◽  
Keiji TAKEMURA ◽  
...  
Keyword(s):  
Active Fault ◽  
Fault System ◽  
Southwest Japan

scholarly journals Latest Rupture Event of the Mino Fault, the Median Tectonic Line Active Fault System, in East Shikoku, Southwest Japan.

2002 ◽  
Vol 111 (5) ◽  
pp. 661-683 ◽  
Author(s):  
Michio MORINO ◽  
Atsumasa OKADA ◽  
Takashi NAKATA ◽  
Koji MATSUNAMI ◽  
Masayoshi KUSAKA ◽  
...  
Keyword(s):  
Active Fault ◽  
Fault System ◽  
Southwest Japan ◽  
Median Tectonic Line ◽  
Tectonic Line

scholarly journals THE BEHAVIOUR OF STRUCTURES BUILT ON ACTIVE FAULT ZONES: EXAMPLES FROM THE RECENT EARTHQUAKES OF TURKEY

2002 ◽  
Vol 19 (2) ◽  
pp. 149s-167s ◽  
Author(s):  
Resat ULUSAY ◽  
Ömer AYDAN ◽  
Masanori HAMADA
Keyword(s):  
Active Fault ◽  
Fault Zones ◽  
Recent Earthquakes
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