Seismogenic fault system of the Mw 6.4 November 2019 Albania earthquake: new insights into the structural architecture and active tectonic setting of the outer Albanides

2021 ◽  
Author(s):  
Simone Teloni ◽  
Chiara Invernizzi ◽  
Stefano Mazzoli ◽  
Pietro Paolo Pierantoni ◽  
Vincenzo Spina
Keyword(s):  
Seismic Hazard ◽  
Tectonic Setting ◽  
Field Analysis ◽  
Fault System ◽  
General Interest ◽  
Seismic Events ◽  
Seismogenic Source ◽  
Active Tectonic ◽  
Structural Architecture ◽  
Recent Earthquakes

<p>Fault geometries are usually reconstructed through seismic data, which can provide a very good image of the subsurface. However, the recognition of deep structures is often difficult for the shallow depth of these data and their low resolution in depth. On the contrary, recent earthquakes and their parameters (e.g. hypocentre, focal mechanism, magnitude, etc.) may have an important role in better understanding deep features, outlining the active crustal structures.</p><p>November 26<sup>th</sup> 2019 a 6.4 M<sub>w</sub> Durres earthquake struck the Albanian coastal area, claiming 51 victims and hundreds of injured people. This seismic sequence sheds new light into the structural architecture and active tectonic setting of the northern outer Albanides. Stress field analysis performed through local mechanisms of the main seismic events of the sequence and those recorded since 1997 by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) confirm that the area is dominated by ENE trending, horizontal maximum compression, with a ENE dipping thrust faults roughly parallel to the coastline. Further analysis to investigate the structural architecture of this area was conducted plotting hypocentre distribution which show that shallower hypocentres tend to cluster around the deeper portion of projected fault segment proposed by the DISS ‘composite seismogenic source’ labelled ALCS002, whereas most of the seismic events including the Mw = 6.4 main shock are nucleated within the crystalline basement. This result unravels for the first time the fundamental role of deeply rooted, crustal ramp-dominated thrusting in seismogenesis, implying a profound reconsideration of the seismotectonic setting of the region.</p><p>The outcomes of this study show here that the recent earthquakes are pivotal in outlining the active crustal frontal structure of the thrust belt, providing new fundamental constraints, not only on the active tectonic setting of the region, but also on the crustal architecture of the outer Albanides. In this regard, the identification of such deep seismogenic sources and the definition of their dimensional parameters may have major implications on the correct assessment of the seismic hazard, especially for this large and densely populated area of Albania. Furthermore, the evidence provided in this study for a deep seismogenic thrust system in a foreland basin setting may be of general interest in similar tectonic contexts worldwide, where deep structures are possibly unidentified, and may represent a weakness in seismic hazard assessment.</p>

The seismogenic fault system of the Mw 6.4, November 2019 Albania earthquake: new insights into the structural architecture and active tectonic setting of the outer Albanides

2020 ◽  
pp. jgs2020-193
Author(s):  
Simone Teloni ◽  
Chiara Invernizzi ◽  
Stefano Mazzoli ◽  
Pietro Paolo Pierantoni ◽  
Vincenzo Spina
Keyword(s):  
Sedimentary Cover ◽  
Tectonic Setting ◽  
Fault System ◽  
Seismogenic Fault ◽  
Active Tectonic ◽  
Seismogenic Structures ◽  
Structural Architecture ◽  
Inversion Analysis ◽  
First Time

A seismic sequence that affected the Durrës region in late 2019 to early 2020 sheds new light into the structural architecture and active tectonic setting of the northern outer Albanides. Stress inversion analysis using the focal mechanisms confirms that the area is dominated by ENE trending, horizontal maximum compression. Seismogenic sources consist mainly of ENE dipping thrust faults roughly parallel to the coastline. Hypocentre distribution indicates that most of the earthquakes, including the Mw = 6.4 main shock, nucleated within the basement, while only some of the shallow aftershocks tend to cluster around the deeper portion of previously identified seismogenic structures within the sedimentary cover. Our results, unravelling for the first time the fundamental role of deeply rooted, crustal ramp-dominated thrusting in seismogenesis, imply a profound reconsideration of the seismotectonic setting of the region in view of a correct assessment of seismic hazard in this densely populated area of Albania.

scholarly journals Fast Holocene slip and localized strain along the Liquiñe-Ofqui strike-slip fault system, Chile

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Luis Astudillo-Sotomayor ◽  
Julius Jara-Muñoz ◽  
Daniel Melnick ◽  
Joaquín Cortés-Aranda ◽  
Andrés Tassara ◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Strain Localization ◽  
Slip Rate ◽  
Strike Slip ◽  
Strike Slip Fault ◽  
Fault System ◽  
Plate Convergence ◽  
Active Tectonic ◽  
Millennial Time Scale ◽  
Hazard Assessments

AbstractIn active tectonic settings dominated by strike-slip kinematics, slip partitioning across subparallel faults is a common feature; therefore, assessing the degree of partitioning and strain localization is paramount for seismic hazard assessments. Here, we estimate a slip rate of 18.8 ± 2.0 mm/year over the past 9.0 ± 0.1 ka for a single strand of the Liquiñe-Ofqui Fault System, which straddles the Main Cordillera in Southern Chile. This Holocene rate accounts for ~ 82% of the trench-parallel component of oblique plate convergence and is similar to million-year estimates integrated over the entire fault system. Our results imply that strain localizes on a single fault at millennial time scale but over longer time scales strain localization is not sustained. The fast millennial slip rate in the absence of historical Mw > 6.5 earthquakes along the Liquiñe-Ofqui Fault System implies either a component of aseismic slip or Mw ~ 7 earthquakes involving multi-trace ruptures and > 150-year repeat times. Our results have implications for the understanding of strike-slip fault system dynamics within volcanic arcs and seismic hazard assessments.

DETERMINISTIC SEISMIC HAZARD ANALYSIS OF ANDAMAN AND NICOBAR ISLANDS

2013 ◽  
Vol 07 (04) ◽  
pp. 1350035
Author(s):  
N. P. KATARIA ◽  
M. SHRIKHANDE ◽  
J. D. DAS
Keyword(s):  
Seismic Hazard ◽  
Hazard Analysis ◽  
Tectonic Setting ◽  
Seismic Hazard Assessment ◽  
Active Regions ◽  
Seismogenic Zone ◽  
Ground Acceleration ◽  
Design Spectrum ◽  
Seismogenic Source ◽  
Deterministic Seismic Hazard

An important component of hazard mitigation is to estimate the future hazard for design calculations. In the present study, a deterministic seismic hazard assessment of Andaman and Nicobar region is carried out, which is one of the most seismically active regions of India. The study area is divided into seven seismogenic source zones based on seismicity and tectonic setting. For ground motion estimation at Andaman and Nicobar, for each seismogenic zone different attenuation relationship is used as per tectonic setting of that seismogenic zone. In order to generate the site specific design spectrum, final results are calculated in the form of peak ground acceleration (PGA) and 5%-damped pseudo-spectral acceleration (PSA) for 0.2 s and 1 s. Calculated results are compared with some earlier works for the studied area and the probable reasons for variations are discussed.

Geochemical composition of Casaglia geothermal fluids and its relationships with the tectonic regime (Emilia-Romagna Region, Italy) 

2021 ◽  
Author(s):  
Silvia Balzan ◽  
Antonio Caracausi ◽  
Giacomo Ferretti ◽  
Anna Saroni ◽  
Giovanni Martinelli ◽  
...  
Keyword(s):  
Thermal State ◽  
Sedimentary Cover ◽  
Tectonic Setting ◽  
Fault System ◽  
Geothermal Heat ◽  
Geochemical Composition ◽  
Tectonic Regime ◽  
Geothermal Fluids ◽  
Active Tectonic

<p>In this study the geochemical composition of the fluids belonging to the geothermic reservoir of Casaglia is presented. The site is located few kilometers northward of Ferrara, probably the only city in Italy whose heating system is fed by the geothermal heat near the top of the Dorsale Ferrarese, a structural anticline raising the Mesozoic limestones up to few hundred meters below the surface. Measurements of the chemical and isotopic composition of the gas phase (e.g., CO<sub>2</sub> and noble gas) were carried out, together with a full characterization of the physico-chemical parameters and the chemistry of the water phase.</p><p>Fluids derive from a well at a depth of about 322+15meters and the temperature of the emerging water is of 78,6 °C, pH of 6.29 and Eh of -470 mV. Salinity is up to 115.6 mS/cm with a TDS varying between 71024 mg/L and 73718 mg/L. The hydrochemical facies is identified as clorurato-alkaline and the Cl/Br ratio suggest mixing with fossil brines. dD and d<sup>18</sup>O vary from 4.70 to 5.02 and from -12.0 to -12.2 respectively. The volatile phase is mainly composed of N<sub>2</sub> (24.9-40.5 %),<sub></sub>CH<sub>4</sub> (21.1-29.5 %) and CO<sub>2</sub> (37.1-18.6 %), with d<sup>13</sup>C(CO<sub>2</sub>), d<sup>13</sup>C(CH<sub>4</sub>) and dD(CH<sub>4</sub>) varying from -4.4 to -3.7 ‰, from -41.7 to 41.2 ‰ and from -152 to -171 ‰, respectively.  The He amounts are extraordinary high (up to 3956 ppm)  with a <sup>3</sup>He/<sup>4</sup>He of 0.02Ra unequivocally pointing to a crustal origin (e.g., Caracausi & Sulli, 2019). The <sup>40</sup>Ar/<sup>36</sup>Ar ratios span the range 300-374, being very close to the same ratio in atmosphere.</p><p>Such high He concentration cannot be explained by a simple steady-state crustal degassing, taking into account the Th and U contents of the sedimentary cover and the metamorphic basement (Coltorti et al. 2011) which lead also to consider that the thermal state of the Casaglia reservoir involve the entire crustal thickness and not only the Mesozoic carbonate succession that hosts the reservoir itself.</p><p>It is inferred that under an active tectonic regime, as it is that where Casaglia is located, the formation of micro-fracturation, due to the field of stress generated by the local seismicity, increases the He release from the rocks and can contribute to the observed He excess in the geothermal reservoirs (e.g., Buttitta et al., 2020). In this respect, the fault system of Dorsale Ferrarese contributes to generate a preferential pathway for rising fluids with consequent mixing phenomena and provides a reasonable explanation about the presence of this high He content in the reservoir.</p><p>References:</p><p>Buttitta D. et al. (2020). Continental degassing of helium in an active tectonic setting (northern Italy): the role of seismicity. Scientific Reports, 10(1), 1–13.</p><p>Caracausi A. & Sulli A. (2019). Outgassing of Mantle Volatiles in Compressional Tectonic Regime Away From Volcanism: The Role of Continental Delamination. Geochemistry, Geophysics, Geosystems, 20(4), 2007–2020.</p><p>Coltorti M. et al. 2011. U and Th content in the Central Apennines continental crust: a contribution to the determination of the geo-neutrinos flux at LNGS. Geoch. Cosmoch. Acta 75, 2271-2294.</p>

scholarly journals SEISMIC VULNERABILITY OF REINFORCED CONCRETE BRIDGES IN PAKISTAN

2022 ◽  
Vol 28 (2) ◽  
pp. 93-105
Author(s):  
Muhammad Khalid Hafiz ◽  
Qaiser-uz-Zaman Khan ◽  
Sohaib Ahmad
Keyword(s):  
Seismic Hazard ◽  
Seismic Vulnerability ◽  
Seismic Hazard Assessment ◽  
Highway Bridges ◽  
Concrete Bridges ◽  
Seismic Retrofitting ◽  
Seismic Zone ◽  
Code Of Practice ◽  
Recent Earthquakes ◽  
Existing Bridges

Different researchers have performed seismic hazard assessment studies for Pakistan using faults sources which differ from Building Code of Pakistan (BCP 2007) with diverse standard deviations. The results of seismic hazard studies indicate that BCP requires gross revision considering micro and macro level investigations. The recent earthquakes in Pakistan also damaged bridge structures and some studies have been conducted by different researchers to investigate capacity of existing bridges. The most of bridge stock in Pakistan has been designed assuming seismic loads as 2%, 4% and 6% of dead loads following West Pakistan Code of Practice for Highway Bridges. The capacity of eight selected real bridges, two from each seismic zone 2A, 2B, 3 & 4 is checked against BCP demands. Static and dynamic analyses were performed and the piers were checked for elastic limits. It is established that piers are on lower side in capacity and the bridges in zone 2A are generally less vulnerable. Whereas the bridges in zone 2B, 3 and 4 are vulnerable from medium to very high level. Hence, an in-depth analytical vulnerability study of bridge stock particularly in high-risk zone needs to be conducted on priority and appropriate seismic retrofitting schemes need to be proposed.

Long-term analysis of the Ionospheric-Total Electron Content (TEC) parameter for the detection of anomalous behaviours potentially related to seismic activity

2021 ◽  
Author(s):  
Roberto Colonna ◽  
Carolina Filizzola ◽  
Nicola Genzano ◽  
Mariano Lisi ◽  
Nicola Pergola ◽  
...  
Keyword(s):  
Correlation Analysis ◽  
Seismic Hazard ◽  
Total Electron Content ◽  
International Workshop ◽  
Thermal Infrared ◽  
Joint Analysis ◽  
Data Series ◽  
Seismic Events ◽  
Electron Content ◽  
Total Electron

<p>In recent decades, many advances have been made on the study of the complex processes involved in the preparatory phases of earthquakes. Over time, different types of parameters (chemical, physical, biological, etc.) have been proposed as indicators of variability potentially related to this process. Among these, space weather parameters are assuming an increasingly important role due to their possible connection to the occurrence of strong and imminent earthquakes. The variations of the Total Electron Content (TEC) have been investigated as an indicator of the ionospheric status potentially affected by earthquake related phenomena.</p><p>In order to discriminate TEC variations related to normal ionospheric cycle as well as to non-terrestrial forcing phenomena (both mostly dominated by the solar cycle and activity) a key role is played by an in-depth and systematic analysis of multi-year historical data series.</p><p>In this work, a multi-year (>20 years) dataset of TEC measurements recorded by the GPS satellite constellation, was analysed using a modified InterQuartile Range (IQR; Liu et al., 2004) method in order to identify anomalous TEC transients. A correlation analysis was performed with seismic events (M≥4) occurred in Italy in between 2000-2020 considering all the period both in presence and in absence of seismic events.</p><p>The results obtained are discussed and compared with the results achieved through an independent RST analysis (Robust Satellite Techniques; Tramutoli, 1998; 2007) carried out on the Earth’s Thermal Infrared Radiation (TIR) parameter.</p><p>Both methodologies, while using a different approach, aim to discriminate anomalous signals from normal fluctuations of the signal itself related to other causes (e.g. meteorological, geographical, etc.) independent on the earthquake occurrence.</p><p>The joint analysis of the results obtained by the two parameters, TEC and TIR, is carried out in order to evaluate how and to what extent a multi-parametric approach can improve (compared with a single parameter approach) Time-Dependent Assessment of Seismic Hazard (T-DASH; Genzano et al., 2020; 2021) in the short-medium term.</p><p>References</p><p>Genzano, N., C. Filizzola, M. Lisi, N. Pergola, and V. Tramutoli (2020), Toward the development of a multi parametric system for a short-term assessment of the seismic hazard in Italy, Ann. Geophys, 63, 5, PA550, doi:10.4401/ag-8227.</p><p>Genzano, N., C. Filizzola, K. Hattori, N. Pergola, and V. Tramutoli (2021), Statistical correlation analysis between thermal infrared anomalies observed from MTSATs and large earthquakes occurred in Japan (2005 - 2015), Journal of Geophysics Research – Solid Earth, doi: 10.1029/2020JB020108 (accepted).</p><p>Liu, J. Y., Chuo, Y. J., Shan, S. J., Tsai, Y. B., Chen, Y. I., Pulinets, S. A., and Yu, S. B. (2004): Pre-earthquake ionospheric anomalies registered by continuous GPS TEC measurements, Ann. Geophys., 22, 1585–1593, https://doi.org/10.5194/angeo-22-1585-2004.</p><p>Tramutoli, V. (1998), Robust AVHRR Techniques (RAT) for Environmental Monitoring: theory and applications, in Proceedings of SPIE, vol. 3496, edited by E. Zilioli, pp. 101–113, doi: 10.1117/12.332714</p><p>Tramutoli, V. (2007), Robust Satellite Techniques (RST) for Natural and Environmental Hazards Monitoring and Mitigation: Theory and Applications, in 2007 International Workshop on the Analysis of Multi-temporal Remote Sensing Images, pp. 1–6, IEEE. doi: 10.1109/MULTITEMP.2007.4293057</p>

scholarly journals Workflow of Digital Field Mapping and Drone-Aided Survey for the Identification and Characterization of Capable Faults: The Case of a Normal Fault System in the Monte Nerone Area (Northern Apennines, Italy)

2020 ◽  
Vol 9 (11) ◽  
pp. 616
Author(s):  
Mauro De Donatis ◽  
Mauro Alberti ◽  
Mattia Cipicchia ◽  
Nelson Muñoz Guerrero ◽  
Giulio F. Pappafico ◽  
...  
Keyword(s):  
Central Italy ◽  
Three Dimensional ◽  
Normal Fault ◽  
Field Work ◽  
Digital Data ◽  
Fault System ◽  
Seismic Profiles ◽  
Postgraduate Students ◽  
Recent Earthquakes

Field work on the search and characterization of ground effects of a historical earthquake (i.e., the Cagli earthquake in 1781) was carried out using terrestrial and aerial digital tools. The method of capturing, organizing, storing, and elaborating digital data is described herein, proposing a possible workflow starting from pre-field project organization, through reiteration of field and intermediate laboratory work, to final interpretation and synthesis. The case of one of the most important seismic events in the area of the northern Umbria–Marche Apennines provided the opportunity to test the method with both postgraduate students and researchers. The main result of this work was the mapping of a capable normal fault system with a great number of observations, as well as a large amount of data, from difficult outcrop areas. A GIS map and a three-dimensional (3D) model, with the integration of subsurface data (i.e., seismic profiles and recent earthquake distribution information), allowed for a new interpretation of an extensional tectonic regime of this Apennines sector, similar to one of the southernmost areas of central Italy where recent earthquakes occurred on 2016.

scholarly journals Weathering of Ophiolite Remnant and Formation of Ni Laterite in a Strong Uplifted Tectonic Region (Yuanjiang, Southwest China)

Minerals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 51 ◽  
Author(s):  
Wei Fu ◽  
Yangyang Feng ◽  
Peng Luo ◽  
Yinmeng Zhang ◽  
Xiaorong Huang ◽  
...  
Keyword(s):  
Southwest China ◽  
Tectonic Setting ◽  
Continuous Operation ◽  
Tectonic Uplift ◽  
Yunnan Plateau ◽  
Active Tectonic ◽  
History Of ◽  
Southwestern Margin ◽  
Planation Surfaces ◽  
Weathering Process

The Yuanjiang Ni deposit in southwestern margin of the Yunnan Plateau is the only economically important lateritic Ni deposit in China. It contains 21.2 Mt ore with an average grade of 1.05 wt % Ni and has been recognized as the second largest Ni producer in China following the Jinchuan super-large magmatic Ni–Cu deposit. This Ni deposit is hosted within the lateritic regolith derived from serpentinite within the regional Paleo-Tethyan Ophiolite remnants. Local landscape controls the distribution of the Ni mineralized regolith, and spatially it is characterized by developing on several stepped planation surfaces. Three types of lateritic Ni ores are identified based on Ni-hosting minerals, namely oxide ore, oxide-silicate mixed ore and silicate ore. In the dominant silicate ore, two phyllosilicate minerals (serpentine and talc) are the Ni-host minerals. Their Ni compositions, however, are remarkably different. Serpentine (0.34–1.2 wt % Ni) has a higher Ni concentration than talc (0.18–0.26 wt % Ni), indicating that the serpentine is more significantly enriched in Ni during weathering process compared to talc. This explains why talc veining reduces Ni grade. The geochemical index (S/SAF value = 0.33–0.81, UMIA values = 17–60) indicates that the serpentinite-derived regolith has experienced, at least, weak to moderate lateritization. Based on several lines of paleoclimate evidence, the history of lateritization at Yuanjiang area probably dates to the Oligocene-Miocene boundary and has extended to the present. With a hydrology-controlled lateritization process ongoing, continuous operation of Ni migration from the serpentinite-forming minerals to weathered minerals (goethite and serpentine) gave rise to the development of three types of Ni ore in the regolith. Notably, the formation and preservation of the Yuanjiang lateritic Ni deposit has been strongly impacted by regional multi-staged tectonic uplift during the development of Yunnan Plateau. This active tectonic setting has promoted weathering of serpentinite and supergene Ni enrichment, but is also responsible for its partial erosion.

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