scholarly journals Imbricated Aseismic Slip and Fluid Diffusion Drive a Seismic Swarm in the Corinth Gulf, Greece

2020 ◽  
Vol 47 (9) ◽  
Author(s):  
Louis De Barros ◽  
Frédéric Cappa ◽  
Anne Deschamps ◽  
Pierre Dublanchet
Keyword(s):  
Aseismic Slip ◽  
Corinth Gulf ◽  
Seismic Swarm ◽  
Fluid Diffusion

Dual seismic migration velocities reveal imbricated fluid diffusion and aseismic slip In a Corinth Gulf  swarm (Greece)

2021 ◽  
Author(s):  
Louis De Barros ◽  
Pierre Dublanchet ◽  
Frédéric Cappa ◽  
Anne Deschamps
Keyword(s):  
Temporal Evolution ◽  
Fluid Pressure ◽  
Normal Fault ◽  
Mechanical Modeling ◽  
Aseismic Slip ◽  
Seismic Migration ◽  
Corinth Gulf ◽  
The Mean ◽  
Earthquake Sequences ◽  
Fluid Diffusion

<p>Fluid induced earthquake sequences generally appear as expanding swarms activating a particular fault. Such swarms are generally interpreted as fluid diffusion, which ignores the possibility of static, dynamic or aseismic triggering, and the existence of rapid migration. Here, we study the temporal evolution of a seismic swarm that occurred over a 10-day period in October 2015 in the extensional rift of the Corinth Gulf (Greece) using high-resolution earthquakes relocations. The seismicity radially migrates on a normal fault at a fluid diffusion velocity (~125 m/day). However, this migration occurs intermittently, with periods of fast expansion (2-to-10 km/day) during short seismic bursts alternating with quiescent periods. Moreover, the growing phases of the swarm illuminate a high number of repeaters. Therefore, we propose a new model to explain the combination of multiple driving processes for such swarms.  Fluid up flow in the fault may induce aseismic slip episodes, separated by phases of fluid pressure build-up. The stress perturbation due to aseismic slip may activate small asperities in the fault that produce bursts of seismicity during the most intense phase of the swarm. We then validated this model through hydro-mechanical modeling, where earthquakes consist in the failure of asperities on a creeping fault infiltrated by fluid. For that, we couple rate‐and‐state friction, non‐linear diffusivity and elasticity along a 1D interface. This model reproduces the dual migration speeds observed in real swarms. We show that migration speeds increase linearly with the mean pressurization, and are not dependent on the hydraulic diffusivity, as traditionally suggested.</p>

Near-Fault Monitoring Reveals Combined Seismic and Slow Activation of a Fault Branch within the Istanbul–Marmara Seismic Gap in Northwest Turkey

2021 ◽  
Author(s):  
Patricia Martínez-Garzón ◽  
Virginie Durand ◽  
Stephan Bentz ◽  
Grzegorz Kwiatek ◽  
Georg Dresen ◽  
...  
Keyword(s):  
Seismic Gap ◽  
Marmara Region ◽  
Fault Rupture ◽  
Aseismic Slip ◽  
Near Fault ◽  
Fault Monitoring ◽  
Aftershock Sequences ◽  
Borehole Strainmeter ◽  
Seismic Moment Release ◽  
Fluid Diffusion

Abstract Various geophysical observations show that seismic and aseismic slip on a fault may occur concurrently. We analyze microseismicity recordings from a temporary near-fault seismic network and borehole strainmeter data from the eastern Marmara region in northwest Turkey to track seismic and aseismic deformation around the hypocentral region of an Mw 4.5 earthquake in 2018. A slow transient is observed that lasted about 30 days starting at the time of the Mw 4.5 event. We study about 1200 microseismic events that occurred during 417 days after the Mw 4.5 event around the mainshock fault rupture. The seismicity reveals a strong temporal clustering, including four episodic seismic sequences, each containing more than 30 events per day. Seismicity from the first two sequences displayed typical characteristics driven by aseismic slip and/or fluids, such as the activation of a broader region around the mainshock and swarm-like topology. The third and fourth sequences correspond to typical mainshock–aftershock sequences. These observations suggest that slow slip and potentially fluid diffusion along the fault plane could have controlled the seismicity during the initial 150 days following the Mw 4.5 event. In contrast, stress redistribution and breaking of remaining asperities may have caused the activity after the initial 150 days. Our observation from a newly installed combined dense seismic and borehole strainmeter network follows an earlier observation of a slow transient occurring in conjunction with enhanced local seismic moment release in the same region. This suggests a frequent interaction of seismic and aseismic slip in the Istanbul–Marmara seismic gap.

The 1989–1990 seismic swarm in the Alban Hills volcanic area, central Italy

1994 ◽  
Vol 61 (3-4) ◽  
pp. 225-237 ◽  
Author(s):  
Alessandro Amato ◽  
Claudio Chiarabba ◽  
Massimo Cocco ◽  
Massimo di Bona ◽  
Giulio Selvaggi
Keyword(s):  
Central Italy ◽  
Volcanic Area ◽  
Seismic Swarm ◽  
Alban Hills

scholarly journals Effect of Modification on the Fluid Diffusion Coefficient in Silica Nanochannels

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 4030
Author(s):  
Gengbiao Chen ◽  
Zhiwen Liu
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Surface Effect ◽  
Bulk Water ◽  
Self Diffusion ◽  
Average Diffusion Coefficient ◽  
Average Diffusion ◽  
Chain Lengths ◽  
Fluid Diffusion ◽  
Self Diffusion Coefficient

The diffusion behavior of fluid water in nanochannels with hydroxylation of silica gel and silanization of different modified chain lengths was simulated by the equilibrium molecular dynamics method. The diffusion coefficient of fluid water was calculated by the Einstein method and the Green–Kubo method, so as to analyze the change rule between the modification degree of nanochannels and the diffusion coefficient of fluid water. The results showed that the diffusion coefficient of fluid water increased with the length of the modified chain. The average diffusion coefficient of fluid water in the hydroxylated nanochannels was 8.01% of the bulk water diffusion coefficient, and the diffusion coefficients of fluid water in the –(CH2)3CH3, –(CH2)7CH3, and –(CH2)11CH3 nanochannels were 44.10%, 49.72%, and 53.80% of the diffusion coefficients of bulk water, respectively. In the above four wall characteristic models, the diffusion coefficients in the z direction were smaller than those in the other directions. However, with an increase in the silylation degree, the increased self-diffusion coefficient due to the surface effect could basically offset the decreased self-diffusion coefficient owing to the scale effect. In the four nanochannels, when the local diffusion coefficient of fluid water was in the range of 8 Å close to the wall, Dz was greater than Dxy, and beyond the range of 8 Å of the wall, the Dz was smaller than Dxy.

scholarly journals Analysis of a large seismically induced mass movement after the December 2018 Etna volcano (southern Italy) seismic swarm

2021 ◽  
Vol 263 ◽  
pp. 112524
Author(s):  
Michele Saroli ◽  
Matteo Albano ◽  
Simone Atzori ◽  
Marco Moro ◽  
Cristiano Tolomei ◽  
...  
Keyword(s):  
Southern Italy ◽  
Mass Movement ◽  
Etna Volcano ◽  
Seismic Swarm

scholarly journals 2013 Seismic swarm recorded in Galati area, Romania: focal mechanism solutions

2016 ◽  
Vol 52 (1) ◽  
pp. 53-67 ◽  
Author(s):  
Andreea Craiu ◽  
Marius Craiu ◽  
Mihail Diaconescu ◽  
Alexandru Marmureanu
Keyword(s):  
Focal Mechanism ◽  
Focal Mechanism Solutions ◽  
Seismic Swarm
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