scholarly journals New Macroseismic and Morphotectonic Constraints to Infer a Fault Model for the 9 (Mw6.1) and 11 January (Mw7.3) 1693 Earthquakes (Southeastern Sicily)

2020 ◽  
Vol 8 ◽  
Author(s):  
C. Pirrotta ◽  
M. S. Barbano
Keyword(s):  
Surface Expression ◽  
Fault System ◽  
Normal Faults ◽  
Seismic Sources ◽  
Macroseismic Data ◽  
Aerial Photos ◽  
North West ◽  
Fault Systems ◽  
Rupture Length ◽  
Main Shocks

This study deals with the earthquakes which occurred in southeastern Sicily in 1693 (January 9 and 11, Mw ≈ 6.1 and 7.3, respectively). Although they have been largely studied, robust and commonly accepted seismic sources are still missing. We performed a revision of the 1693 macroseismic data and, for the fore and main-shocks, modeled new NNE-SSW trending seismic sources. In the Hyblean Plateau area, we carried out an analysis of DEM and aerial photos to map tectonic features. Then, we performed field surveys on the main faults, and a morphotectonic study with the aim of characterizing the activity of mapped faults. The study revealed the presence of three main fault systems. The first is the Palazzolo-Villasmundo Fault System, composed of NNE-SSW and NE-SW trending north-west-dipping normal faults. Some of these faults could be reactivated as reverse faults. The second is the Augusta-Floridia Fault System, made of NNW-SSE and NW-SE normal faults. The third is composed of faults which have never been mapped before: the Canicattini-Villasmundo Fault System that shows both a segmented and stepping pattern, almost N-S trending and west-dipping normal faults; some of these faults show a left-lateral movement. The morphotectonic study demonstrated that the fault systems are active. Furthermore, both strike and kinematics of the studied faults well match with the regional stress field characterized by a NW-SE σ1, which in the study area is probably both affecting some pre-existing faults, the Palazzolo-Villasmundo and the Augusta-Floridia Fault Systems, and causing the formation of new faults, the Canicattini-Villasmundo Fault System. The latter system lies across the Hyblean Plateau with a total length of 35 km and, due to its aligned segmented pattern, it can be the surface expression of a master fault that seems dividing the Hyblean Plateau in two blocks. Moreover, the Canicattini-Villasmundo Fault System well fits the southern part of the 1693 revaluated seismic sources and matches with a current alignment of shocks mainly characterized by left-lateral focal mechanisms on almost N-S fault planes. Considering the possible rupture length in depth, it could manage to release Mw ≈ 7.1 earthquakes, representing a valuable candidate source for the 1693 earthquakes.

scholarly journals Seismic characteristics of polygonal fault systems in the Great South Basin, New Zealand

2020 ◽  
Vol 12 (1) ◽  
pp. 851-865
Author(s):  
Sukonmeth Jitmahantakul ◽  
Piyaphong Chenrai ◽  
Pitsanupong Kanjanapayont ◽  
Waruntorn Kanitpanyacharoen
Keyword(s):  
Three Dimensional ◽  
Late Eocene ◽  
Seismic Survey ◽  
Fault System ◽  
Normal Faults ◽  
Tier 2 ◽  
South Basin ◽  
Fault Systems ◽  
Tier 1 ◽  
Polygonal Fault

AbstractA well-developed multi-tier polygonal fault system is located in the Great South Basin offshore New Zealand’s South Island. The system has been characterised using a high-quality three-dimensional seismic survey tied to available exploration boreholes using regional two-dimensional seismic data. In this study area, two polygonal fault intervals are identified and analysed, Tier 1 and Tier 2. Tier 1 coincides with the Tucker Cove Formation (Late Eocene) with small polygonal faults. Tier 2 is restricted to the Paleocene-to-Late Eocene interval with a great number of large faults. In map view, polygonal fault cells are outlined by a series of conjugate pairs of normal faults. The polygonal faults are demonstrated to be controlled by depositional facies, specifically offshore bathyal deposits characterised by fine-grained clays, marls and muds. Fault throw analysis is used to understand the propagation history of the polygonal faults in this area. Tier 1 and Tier 2 initiate at about Late Eocene and Early Eocene, respectively, based on their maximum fault throws. A set of three-dimensional fault throw images within Tier 2 shows that maximum fault throws of the inner polygonal fault cell occurs at the same age, while the outer polygonal fault cell exhibits maximum fault throws at shallower levels of different ages. The polygonal fault systems are believed to be related to the dewatering of sedimentary formation during the diagenesis process. Interpretation of the polygonal fault in this area is useful in assessing the migration pathway and seal ability of the Eocene mudstone sequence in the Great South Basin.

scholarly journals Joint Interpretation of Geophysical Results and Geological Observations for Detecting Buried Active Faults: The Case of the “Il Lago” Plain (Pettoranello del Molise, Italy)

2021 ◽  
Vol 13 (8) ◽  
pp. 1555
Author(s):  
Rosa Nappi ◽  
Valeria Paoletti ◽  
Donato D’Antonio ◽  
Francesco Soldovieri ◽  
Luigi Capozzoli ◽  
...  
Keyword(s):  
Seismic Tomography ◽  
Active Faults ◽  
Low Frequency ◽  
Normal Fault ◽  
Seismic Source ◽  
Fault System ◽  
Normal Faults ◽  
Macroseismic Data ◽  
Epicentral Area ◽  
Seismogenic Source

We report a geophysical study across an active normal fault in the Southern Apennines. The surveyed area is the “Il Lago” Plain (Pettoranello del Molise), at the foot of Mt. Patalecchia (Molise Apennines, Southern Italy), a small tectonic basin filled by Holocene deposits located at the NW termination of the major Quaternary Bojano basin structure. This basin, on the NE flank of the Matese Massif, was the epicentral area of the very strong 26 July, 1805, Sant’Anna earthquake (I0 = X MCS, Mw = 6.7). The “Il Lago” Plain is bordered by a portion of the right-stepping normal fault system bounding the whole Bojano Quaternary basin (28 km long). The seismic source responsible for the 1805 earthquake is regarded as one of the most hazardous structures of the Apennines; however, the position of its NW boundary of this seismic source is debated. Geological, geomorphological and macroseismic data show that some coseismic surface faulting also occurred in correspondence with the border fault of the “Il Lago” Plain. The study of the “Il Lago” Plain subsurface might help to constrain the NW segment boundary of the 1805 seismogenic source, suggesting that it is possibly a capable fault, source for moderate (Mw < 5.5) to strong earthquakes (Mw ≥ 5.5). Therefore, we constrained the geometry of the fault beneath the plain using low-frequency Ground Penetrating Radar (GPR) data supported by seismic tomography. Seismic tomography yielded preliminary information on the subsurface structures and the dielectric permittivity of the subsoil. A set of GPR parallel profiles allowed a quick and high-resolution characterization of the lateral extension of the fault, and of its geometry at depth. The result of our study demonstrates the optimal potential of combined seismic and deep GPR surveys for investigating the geometry of buried active normal faults. Moreover, our study could be used for identifying suitable sites for paleoseismic analyses, where record of earthquake surface faulting might be preserved in Holocene lacustrine sedimentary deposits. The present case demonstrates the possibility to detect with high accuracy the complexity of a fault-zone within a basin, inferred by GPR data, not only in its shallower part, but also down to about 100 m depth.

Structural analysis of supracrustal faults in the Charlevoix area, Quebec: relation to impact cratering and the St-Laurent fault system

2003 ◽  
Vol 40 (2) ◽  
pp. 221-235 ◽  
Author(s):  
Yvon Lemieux ◽  
Alain Tremblay ◽  
Denis Lavoie
Keyword(s):  
Impact Crater ◽  
Fault System ◽  
Normal Faults ◽  
Impact Cratering ◽  
Grenville Province ◽  
Fault Systems ◽  
Iapetus Ocean ◽  
Before And After ◽  
Post Impact ◽  
Brittle Faulting

The Charlevoix area, which is host to an impact structure of Devonian age, straddles the boundaries among crystalline rocks of the Grenville Province, the Cambrian–Ordovician sedimentary succession of the St. Lawrence Platform, and accreted units of the Appalachian orogen. The area features well-developed supracrustal fault systems attributed to impact cratering. A major fault system oriented from northeast to northwest consists of normal faults marked by cataclastic and gouge breccias and, less frequently, by pseudotachylyte. Detailed mapping of faults both within and outside the Charlevoix impact crater suggests that brittle faulting occurred both before and after impact cratering. Polymictic fault breccias occurring along some supracrustal faults are the clearest evidence of impact-related fault rocks in the Charlevoix area. The St-Laurent fault, trending to the northeast, represents a major structure interpreted as being related to Late Proterozoic – early Paleozoic rifting of the Iapetus Ocean. However, the St-Laurent fault crosses the Charlevoix impact crater without major deflection, suggesting post-impact reactivation. The fault systems in the Charlevoix area are interpreted to be pre-impact structures related to the opening of the Iapetus Ocean, most of which have also been reactivated during the Devonian cratering event and in post-impact time, the latter most likely coeval with the Atlantic Ocean rifting in Mesozoic time.

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.

P-wave spectra for ML 5 foreshocks, aftershocks, and isolated earthquakes near Parkfield, California

1981 ◽  
Vol 71 (2) ◽  
pp. 423-436
Author(s):  
Willian H. Bakun ◽  
Thomas V. McEvilly
Keyword(s):  
Stress Drop ◽  
High Stress ◽  
P Wave ◽  
Wave Radiation ◽  
Focal Region ◽  
Wave Spectra ◽  
Rupture Length ◽  
Main Shocks ◽  
Relative Stress ◽  
Fault Trace

abstract Wood-Anderson seismograms recorded at Mount Hamilton (MHC, 185 km, 327°), Santa Barbara (SBC, 180 km, 158°), and Tinemaha (TIN, 240 km, 56°) provide data for comparing P-wave spectra for two immediate (17-min) foreshocks, one early (55-hr) foreshock, two aftershocks, and two “isolated” Parkfield earthquakes. All are ML 5.0 shocks with epicenters within 7 km of the common epicenter of the 1934 and 1966 Parkfield main shocks. The set of events is well suited for testing the hypothesis that foreshocks are high-stress-drop sources. Calculated stress drops are controlled by source directivity at azimuths aligned with the fault break (at MHC and SBC). P-wave radiation from the three foreshocks is focused along one fault trace azimuth, suggesting that foreshock sources are characterized by pronounced unilateral rupture expansion. At TIN, broadside to the fault where directivity has minimum effect on calculated relative stress drop, the two immediate foreshocks are higher stress-drop sources. The early foreshock is a low-to-average stress-drop source, indicating the possibility that stress concentration is a rapidly occurring phenomenon in rupture nucleation. Alternatively, the stress field is highly variable on the scale of 2 to 3 km in the focal region of an impending earthquake with a rupture length of 20 to 30 km.

scholarly journals Influence of inherited structural domains and their particular strain distributions on the Roer Valley Graben evolution from inversion to extension

2020 ◽  
Author(s):  
Jef Deckers ◽  
Bernd Rombaut ◽  
Koen Van Noten ◽  
Kris Vanneste
Keyword(s):  
Late Cretaceous ◽  
Fault System ◽  
Normal Faults ◽  
Geological Model ◽  
Structural Domains ◽  
Stress Directions ◽  
Roer Valley Graben ◽  
Western Border ◽  
Border Fault ◽  
As Stress

Abstract. After their first development in the middle Mesozoic, the overall NW-SE striking border fault systems of the Roer Valley Graben were reactivated as reverse faults under Late Cretaceous compression (inversion) and reactivated again as normal faults under Cenozoic extension. In Flanders (northern Belgium), a new geological model was created for the western border fault system of the Roer Valley Graben. After carefully evaluating the new geological model, this study shows the presence of two structural domains in this fault system with distinctly different strain distributions during both Late Cretaceous compression and Cenozoic extension. A southern domain is characterized by narrow ( 10 km) distributed faulting. The total normal and reverse throw in the two domains was estimated to be similar during both tectonic phases. The repeated similarities in strain distribution during both compression and extension stresses the importance of inherited structural domains on the inversion/rifting kinematics besides more obvious factors such as stress directions. The faults in both domains strike NW-SE, but the change in geometry between them takes place across the oblique WNW-ESE striking Grote Brogel fault. Also in other parts of the Roer Valley Graben, WNW-ESE striking faults are associated with major geometrical changes (left-stepping patterns) in its border fault system. This study thereby demonstrates the presence of different long-lived structural domains in the Roer Valley Graben, each having their particular strain distributions that are related to the presence of non-colinear faults.

scholarly journals Structural cross sections through the Corinth-Patras detachment fault-system in Northern Peloponnesus (Aegean Arc, Greece)

2001 ◽  
Vol 34 (1) ◽  
pp. 235 ◽  
Author(s):  
N. FLOTTÉ ◽  
D. SOREL
Keyword(s):  
Cross Sections ◽  
Detachment Fault ◽  
Fault System ◽  
Normal Faults ◽  
Field Observations ◽  
Structural Mapping ◽  
The North ◽  
Gulf Of Corinth ◽  
Aegean Arc

Structural mapping in northern Peloponnesus reveals the emergence of an E-W striking, more than 70km long, low angle detachment fault dipping to the north beneath the Gulf of Corinth. This paper describes four north-south structural cross-sections in northern Peloponnesus. Structural and sedimentological field observations show that in the studied area the normal faults of northern Peloponnesus branch at depth on this major low angle north-dipping brittle detachment. The southern part of the detachment and the related normal faults are now inactive. To the north, the active Helike and Aigion normal faults are connected at depth with the seismically active northern part of the detachment beneath the Gulf of Corinth.

Active Fault Systems in the inner North West Apennines: an updated view

2021 ◽  
Author(s):  
Giancarlo Molli ◽  
Rick Bennett ◽  
Jacques Malavieille ◽  
Enrico Serpelloni ◽  
Fabrizio Storti ◽  
...  
Keyword(s):  
Active Fault ◽  
Central Italy ◽  
Structural Features ◽  
Structural Studies ◽  
Data Set ◽  
Structural Domains ◽  
North West ◽  
Fault Systems ◽  
Internal Fault ◽  
Fault Characterization

&lt;p&gt;As part of an ongoing project of mapping, structural studies and fault characterization we present an updated tectonic scheme and data set for the active fault systems that shaped the inner portion of the Apennines north of the Arno river. Geomorphology, stratigraphy of Plio-Quaternary sediments, GPS data, historical and instrumental seismicity have been reviewed and combined with structural studies to define the neotectonic history of the investigated region. Within the studied area, first-order physiographic and structural features allow to define different structural domains related to a set of ranges with a dominant NW-SE direction separated by intramontane or continental/marine morphotectonic depressions of the Lunigiana, Garfagnana, Lucca-Mt.Albano, La Spezia-Carrara and the off-shore Viareggio basin. The main boundary faults and internal fault segments of the different structural domains were described while the Plio-Quaternary sedimentary records has been used to constrain their long to short term deformation and rates, with the aim to improve current Italian catalogues - DISS (INGV) and Ithaca (ISPRA) - with some utilities for the seismic microzonation local projects. Moreover, our work aims to draw the attention of the scientific community to the seismotectonics of a region in which the seismic hazard is largely considered medium to low despite the occurrence, one century ago, of one of the most destructive earthquakes that have struck the Italian peninsula, the 1920 Fivizzano EQ, with an estimated Mw 6.5 similar to the main shock of the 2016 Central Italy seismic sequence.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Mapping the regional tectonic asset of the Discovery quadrangle of Mercury

2021 ◽  
Author(s):  
Valentina Galluzzi ◽  
Luigi Ferranti ◽  
Lorenza Giacomini ◽  
Pasquale Palumbo
Keyword(s):  
Imaging System ◽  
Space Environment ◽  
Fault System ◽  
Geophysical Research ◽  
Fault Systems ◽  
Space Agency ◽  
Regional Tectonic ◽  
Italian Space Agency ◽  
Dual Imaging ◽  
Map Series

&lt;p&gt;The Discovery quadrangle of Mercury (H-11) located in the area between 22.5&amp;#176;S&amp;#8211;65&amp;#176;S and 270&amp;#176;E&amp;#8211;360&amp;#176;E encompasses structures of paramount importance for understanding Mercury&amp;#8217;s tectonics. The quadrangle is named after Discovery Rupes, a NE-SW trending lobate scarp, which is one of the longest and highest on Mercury (600 km in length and 2 km high). By examining the existing maps of this area (Trask and Dzurisin, 1984; Byrne et al., 2014), several other oblique trending structures are visible. More mapping detail could be achieved by using the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) Mercury Dual Imaging System (MDIS) imagery.&lt;/p&gt; &lt;p&gt;We aim at mapping the structures of H-11 at high-resolution by using MESSENGER/MDIS basemaps, in order to understand its regional tectonic history by following the work done in the Victoria quadrangle (H-2) (Galluzzi et al., 2019). Differently from H-2, located in the same longitudinal range but at opposite latitudes, this area lacks in N-S trending scarps, such as the Victoria-Endeavour-Antoniadi fault system, which dominates the northern hemisphere structural framework. The existing tectonic theories predict either an isotropic pattern of faults (global contraction) or an ordered distribution and orientation of faults (tidal despinning) for Mercury. If we expect that the existing tectonic patterns were governed by only one of the two processes or both together, it is difficult to understand how such different trends formed within these two complementary areas. The structural study done for H-2 reveals that the geochemical discontinuities present in Mercury&amp;#8217;s crust may have guided and influenced the trend and kinematics of faults in that area (Galluzzi et al., 2019). In particular, the high-magnesium region seems to be associated with fault systems that either follow its boundary or are located within it. These fault systems show distinct kinematics and trends. The south-eastern border of the HMR is located within H-11. Hence, with this study, we aim at complementing the previous one to better describe the tectonics linked to the presence of the HMR. Furthermore, this geostructural map will complement the future geomorphological map of the area and will be part of the 1:3M quadrangle geological map series which are being prepared in view of the BepiColombo mission (Galluzzi, 2019). &lt;em&gt;Acknowledgments: We gratefully acknowledge funding from the Italian Space Agency (ASI) under ASI-INAF agreement 2017-47-H.0.&lt;/em&gt;&lt;/p&gt; &lt;p&gt;Byrne et al. (2014). Nature Geoscience, 7(4), 301-307.&lt;br /&gt;Galluzzi, V. (2019). In: Planetary Cartography and GIS, Springer, Cham, 207-218.&lt;br /&gt;Galluzzi et al. (2019). Journal of Geophysical Research: Planets, 124(10), 2543-2562.&lt;br /&gt;Trask and Dzurisin (1984). USGS, IMAP 1658.&lt;/p&gt;

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