scholarly journals The 31 March 2020 Mw 6.5 Stanley, Idaho, Earthquake: Seismotectonics and Preliminary Aftershock Analysis

2020 ◽  
Author(s):  
Lee M. Liberty ◽  
Zachery M. Lifton ◽  
T. Dylan Mikesell
Keyword(s):  
Surface Displacement ◽  
Volcanic Belt ◽  
Normal Fault ◽  
Fault System ◽  
Basin And Range Province ◽  
Ground Shaking ◽  
The North ◽  
Show Evidence ◽  
Tectonic Framework ◽  
Tectonic Belt

Abstract We report on the tectonic framework, seismicity, and aftershock monitoring efforts related to the 31 March 2020 Mw 6.5 Stanley, Idaho, earthquake. The earthquake sequence has produced both strike-slip and dip-slip motion, with minimal surface displacement or damage. The earthquake occurred at the northern limits of the Sawtooth normal fault. This fault separates the Centennial tectonic belt, a zone of active seismicity within the Basin and Range Province, from the Idaho batholith to the west and Challis volcanic belt to the north and east. We show evidence for a potential kinematic link between the northeast-dipping Sawtooth fault and the southwest-dipping Lost River fault. These opposing faults have recorded four of the five M≥6 Idaho earthquakes from the past 76 yr, including 1983 Mw 6.9 Borah Peak and the 1944 M 6.1 and 1945 M 6.0 Seafoam earthquakes. Geological and geophysical data point to possible fault boundary segments driven by pre-existing geologic structures. We suggest that the limits of both the Sawtooth and Lost River faults extend north beyond their mapped extent, are influenced by the relic trans-Challis fault system, and that seismicity within this region will likely continue for the coming years. Ongoing seismic monitoring efforts will lead to an improved understanding of ground shaking potential and active fault characteristics.

scholarly journals Neogene-Quaternary tectonic regime and macroseismic observations in the Tyrnavos-Elassona broader epicentral area of the March 2021, intense earthquake sequence

2021 ◽  
Vol 58 ◽  
pp. 200
Author(s):  
Dimitrios Galanakis ◽  
Sotiris Sboras ◽  
Garyfalia Konstantopoulou ◽  
Markos Xenakis
Keyword(s):  
Normal Fault ◽  
Fault Scarp ◽  
Focal Mechanisms ◽  
Fault System ◽  
Spatiotemporal Evolution ◽  
Surface Rupture ◽  
Alluvial Deposits ◽  
Epicentral Area ◽  
Ground Shaking ◽  
Macroseismic Observations

On March 3, 2021, a strong (Mw6.3) earthquake occurred near the towns of Tyrnavos and Elassona. One day later (March 4), a second strong (Mw6.0) earthquake occurred just a few kilometres toward the WNW. The aftershock spatial distribution and the focal mechanisms revealed NW-SE-striking normal faulting. The focal mechanisms also revealed a NE-SW oriented extensional stress field, different from the orientation we knew so far (ca. N-S). The magnitude and location of the two strongest shocks, and the spatiotemporal evolution of the sequence, strongly suggest that two adjacent fault segments were ruptured respectively. The sequence was followed by several coseismic ground deformational phenomena, such as landslides/rockfalls, liquefaction and ruptures. The landslides and rockfalls were mostly associated with the ground shaking. The ruptures were observed west of the Titarissios River, near to the Quaternary faults found by bore-hole lignite investigation. In the same direction, a fault scarp separating the alpidic basement from the alluvial deposits of the Titarissios valley implies the occurrence of a well-developed fault system. Some of the ground ruptures were accompanied by extensive liquefaction phenomena. Others cross-cut reinforced concrete irrigation channels without changing their direction. We suggest that this fault system was partially reactivated, as a secondary surface rupture, during the sequence as a steeper splay of a deeper low-to-moderate angle normal fault.

scholarly journals Accretion, Soft and Hard Collision: Similarities, Differences and an Application from the Newfoundland Appalachian Orogen

2020 ◽  
Vol 47 (3) ◽  
pp. 103-118
Author(s):  
Cees Van Staal ◽  
Alexandre Zagorevski
Keyword(s):  
Volcanic Rocks ◽  
Leading Edge ◽  
Qualitative Assessment ◽  
Fault System ◽  
Accretionary Wedge ◽  
The North ◽  
Show Evidence ◽  
Accreted Terranes ◽  
Mountain Belts ◽  
Laurentian Margin

We argue there is no distinction between accretion and collision as a process, except when accretion is used in the sense of incorporating small bodies of sedimentary and/or volcanic rocks into an accretionary wedge by off-scraping or underplating. There is also a distinction when these terms are used in classifying mountain belts into accretionary and collisional orogens, although such classifications are commonly based on a qualitative assessment of the scale and nature of the accreted terranes and continents involved in formation of mountain belts. Soft collisions occur when contractional deformation and associated metamorphism are principally concentrated in rocks of the leading edge of the partially pulled-down buoyant plate and the upper plate forearc terrane. Several young arc-continent collisions show evidence for partial or wholesale subduction of the forearc such that the arc is structurally juxtaposed directly against lower plate rocks. This process may explain the poor preservation of forearcs in the geological record. Soft collisions generally change into hard collisions over time, except if the collision is rapidly followed by formation of a new subduction zone due to step-back or polarity reversal. Thickening and metamorphism of the arc's suprastructure and retro-arc part of upper plate due to contractional deformation and burial are the characteristics of a hard collision or an advancing Andean-type margin. Strong rheological coupling of the converging plates and lower and upper crust in the down-going continental margin promotes a hard collision. Application of the soft–hard terminology supports a structural juxtaposition of the Taconic soft collision recorded in the Humber margin of western Newfoundland with a hard collision recorded in the adjacent Dashwoods block. It is postulated that Dashwoods was translated dextrally along the Cabot-Baie Verte fault system from a position to the north of Newfoundland where the Notre Dame arc collided ca. 10 m.y. earlier with a wide promontory in a hyperextended segment of the Laurentian margin.

scholarly journals Structure and kinematics of an extensional growth fold, Hadahid Fault System, Suez Rift, Egypt

2019 ◽  
Author(s):  
Christopher Aiden-Lee Jackson ◽  
Paul S Whipp ◽  
Robert Gawthorpe ◽  
Matthew M Lewis
Keyword(s):  
Structural Complexity ◽  
Surface Displacement ◽  
Normal Fault ◽  
Fault System ◽  
Length Scale ◽  
Slip Ratio ◽  
Continental Extension ◽  
Structural Style ◽  
Progressive Loss ◽  
Geometry And Kinematics

Normal faulting drives extensional growth folding of the Earth’s upper crust during continental extension, yet we know little of how fold geometry relates to the structural segmentation of the underlying fault. We use field data from the Hadahid Fault System, Suez Rift, Egypt to investigate the geometry and kinematics of a large (30 km long, up to 2.5 km displacement), exceptionally well-exposed normal fault system to test and develop models for extensional growth folding. The Hadahid Fault System comprises eight, up to 5 km long segments that are defined by unbreached or breached monoclines. These segments are soft-linked, hard-linked, or defined by a more subtle along-strike transition in overall structural style. High overlap:separation (O:S) ratios between its segments suggest the Hadahid Fault System comprises a single, now hard-linked structure at-depth. We demonstrate that a progressive loss of at-surface displacement along strike of the Hadahid Fault System results in surface-breaking faults and breached monoclines being replaced by unbreached monoclines developed above blind faults. However, shorter along-strike length-scale variations in structural style also occur, with unbreached monoclines developed between breached monoclines. The origin of this variability is unclear, but might reflect local variations in host rock material properties that drive short length-scale variations in fault propagation-to-slip ratio, and thus the timing and location of fold breaching. We show that folding is a key expression of the strain that accumulates in areas of continental extension, and argue that tectono-sedimentary models for rift development should capture the related structural complexity.

scholarly journals Brittle tectonic and morphological alteration of Almyros basin

2001 ◽  
Vol 34 (1) ◽  
pp. 371
Author(s):  
Δ. ΓΑΛΑΝΑΚΗΣ
Keyword(s):  
Drainage System ◽  
Normal Fault ◽  
Vertical Displacement ◽  
Fault System ◽  
Morphological Alteration ◽  
Southern Boundary ◽  
Fault Systems ◽  
The North ◽  
River Terraces ◽  
Morphotectonic Evolution

Two crossed fault systems with NW-SE and E-W directions affect on the central and southern part of the Almyros basin. The uplift movement in the western part of the basin, with importance vertical displacement (up to 200m) of the lignite layers and the formation river terraces are related with the activity of the first fault NWSE direction. The second fault with E-W direction, located along Xerias river, affect on drainage system with hydrographie network from the south to the north development. In the southern part of the basin and on the Orthrys mountain a fault system with E-W trending affects on alpine basement and neogene deposits. This fault system forms the southern boundary of the Almyros basin. The recent brittle tectonic during Neogene-Quaternary is connected with the evolution and the configuration of the Almyros basin as well as volcanic activity of the area. The morphological differentiations of Almyros basin, the drainage system and the recent landforms with morphogenic activity are controlled by the recent brittle tectonics. The normal fault systems in the studied area caused by the extensional stress field (σ3), trending N-S to NNW-SSE, which controls the geodynamic regime since Lower Pleistocene. This geodynamic regime has defined the recent morphological and morphotectonic evolution of the studied area.

scholarly journals Recent Activity and Kinematics of the Bounding Faults of the Catanzaro Trough (Central Calabria, Italy): New Morphotectonic, Geodetic and Seismological Data

Geosciences ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 405
Author(s):  
Claudia Pirrotta ◽  
Graziella Barberi ◽  
Giovanni Barreca ◽  
Fabio Brighenti ◽  
Francesco Carnemolla ◽  
...  
Keyword(s):  
Scaling Laws ◽  
Normal Fault ◽  
Historical Earthquakes ◽  
Fault System ◽  
Normal Faults ◽  
The North ◽  
Seismological Data ◽  
Geomorphic Features ◽  
Half Graben ◽  
Fault Scarps

A multidisciplinary work integrating structural, geodetic and seismological data was performed in the Catanzaro Trough (central Calabria, Italy) to define the seismotectonic setting of this area. The Catanzaro Trough is a structural depression transversal to the Calabrian Arc, lying in-between two longitudinal grabens: the Crati Basin to the north and the Mesima Basin to the south. The investigated area experienced some of the strongest historical earthquakes of Italy, whose seismogenic sources are still not well defined. We investigated and mapped the major WSW–ENE to WNW–ESE trending normal-oblique Lamezia-Catanzaro Fault System, bounding to the north the Catanzaro Trough. Morphotectonic data reveal that some fault segments have recently been reactivated since they have displaced upper Pleistocene deposits showing typical geomorphic features associated with active normal fault scarps such as triangular and trapezoidal facets, and displaced alluvial fans. The analysis of instrumental seismicity indicates that some clusters of earthquakes have nucleated on the Lamezia-Catanzaro Fault System. In addition, focal mechanisms indicate the prevalence of left-lateral kinematics on E–W roughly oriented fault plains. GPS data confirm that slow left-lateral motion occurs along this fault system. Minor north-dipping normal faults were also mapped in the southern side of the Catanzaro Trough. They show eroded fault scarps along which weak seismic activity and negligible geodetic motion occur. Our study highlights that the Catanzaro Trough is a poliphased Plio-Quaternary extensional basin developed early as a half-graben in the frame of the tear-faulting occurring at the northern edge of the subducting Ionian slab. In this context, the strike-slip motion contributes to the longitudinal segmentation of the Calabrian Arc. In addition, the high number of seismic events evidenced by the instrumental seismicity, the macroseismic intensity distribution of the historical earthquakes and the scaling laws relating to earthquakes and seismogenic faults support the hypothesis that the Lamezia-Catanzaro Fault System may have been responsible for the historical earthquakes since it is capable of triggering earthquakes with magnitude up to 6.9.

scholarly journals Past earthquake timing and magnitude along the Inglewood fault, Taranaki, New Zealand

1994 ◽  
Vol 27 (2) ◽  
pp. 155-162 ◽  
Author(s):  
A. G. Hull
Keyword(s):  
Volcanic Ash ◽  
Surface Displacement ◽  
Normal Fault ◽  
Historical Earthquakes ◽  
Normal Faults ◽  
Single Event ◽  
Ground Shaking ◽  
Large Earthquakes ◽  
Fault Length ◽  
Strong Ground

Several active normal faults in the onshore and offshore regions of Taranaki are capable of generating large earthquakes and associated strong ground shaking. Historical earthquakes are concentrated offshore of Cape Egmont, and no significant earthquakes have been detected along the major onshore surface faults. The northeaststriking Inglewood fault is a major onshore, southward-dipping normal fault. It has a known length of c. 20 km and an average scarp height of c. 3 m on landforms less than about 15,000 yrs old. Three subsurface excavations at two sites along the Inglewood fault about 15 km from New Plymouth have revealed three surface fault displacements during the last c. 13,000 years. Earthquakes resulting in about 1.2 m of surface displacement occurred at c. 3,500 radiocarbon yrs BP; between 4,000 and 9,000 radiocarbon yrs BP; and between 10,000 and 13,000 radiocarbon yrs BP, judged by the amount of vertical offset of dated volcanic ash layers. Based on average single-event fault slip values of 1.2-3.0 m and a fault length of 20-30 km, the estimated earthquake magnitudes associated with these past movements range from Mw 6.7 to 7.2.

scholarly journals Structure and kinematics of an extensional growth fold, Hadahid Fault System, Suez Rift, Egypt

Solid Earth ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 1027-1051
Author(s):  
Christopher A.-L. Jackson ◽  
Paul S. Whipp ◽  
Robert L. Gawthorpe ◽  
Matthew M. Lewis
Keyword(s):  
Structural Complexity ◽  
Surface Displacement ◽  
Normal Fault ◽  
Fault System ◽  
Length Scale ◽  
Slip Ratio ◽  
Continental Extension ◽  
Structural Style ◽  
Progressive Loss ◽  
Geometry And Kinematics

Abstract. Normal faulting drives extensional growth folding of the Earth's upper crust during continental extension, yet we know little of how fold geometry relates to the structural segmentation of the underlying fault. We use field data from the Hadahid Fault System, Suez Rift, Egypt, to investigate the geometry and kinematics of a large (30 km long, up to 2.5 km displacement), exceptionally well-exposed normal fault system and to test and develop models for extensional growth folding. The Hadahid Fault System comprises eight up to 5 km long segments that are defined by unbreached or breached monoclines. These segments are soft-linked, hard-linked, or defined by a more subtle along-strike transition in overall structural style. High overlap : separation (O:S) ratios between its segments suggest the Hadahid Fault System comprises a single, now hard-linked structure at depth. We demonstrate that a progressive loss of at-surface displacement along-strike of the Hadahid Fault System results in surface-breaking faults and breached monoclines being replaced by unbreached monoclines developed above blind faults. However, shorter along-strike length-scale variations in structural style also occur, with unbreached monoclines developed between breached monoclines. The origin of this variability is unclear, but it might reflect local variations in host rock material properties that drive short length-scale variations in fault propagation-to-slip ratio, and thus the timing and location of fold breaching. We show that folding is a key expression of the strain that accumulates in areas of continental extension, arguing that tectono-sedimentary models for rift development should capture the related structural complexity.

Full characterization of the ML 5.4 2019/11/11 Le Teil earthquake in France based on a multi-technology approach

2020 ◽  
Author(s):  
Amaury Vallage ◽  
Laurent Bollinger ◽  
Yoann Cano ◽  
Johann Champenois ◽  
Clara Duverger ◽  
...  
Keyword(s):  
Focal Mechanism ◽  
Ground Deformation ◽  
Waveform Inversion ◽  
Normal Fault ◽  
Fault System ◽  
Tectonic Deformation ◽  
Reverse Fault ◽  
Ground Shaking ◽  
Full Characterization ◽  
Stable Continental Region

<p>Metropolitan France is a region of slow tectonic deformation rates with sparse historical and instrumental seismicity, and where geodesy is not able to reach the required resolution in order to resolve the tectonic loadings. The few faults recognized as potential active rely on rare neotectonic slip rates, often integrated over geological scales.</p><p>In this context, the M<sub>L</sub> 5.4 Le Teil 2019 earthquake is of particular interest because it is the largest seismic event recorded in metropolitan France in the last 16 years. The last regional earthquake with a larger magnitude was the Lambesc event that occurred in 1909 about 110 km away from Le Teil epicenter. This recent earthquake offers a noteworthy opportunity to combine different technologies: seismological observations (RESIF and CEA) with satellite InSAR data and infrasound measurements, to help characterizing this stable continental region.</p><p>The analysis shows that the focal mechanism determined from the full waveform inversion of long-period seismological data is consistent with the activation of a reverse fault with a strike around 45°N and is associated with a moment magnitude of 4.8. Moreover, this event produced infrasound signals recorded by the OHP Alpine array located 110 km away. The analysis of these signals provides evidence of ground-to-air coupling in the epicentral region as well as ground shaking information.</p><p>Despite the moderate magnitude of the event, the ground deformation is resolved by InSAR with Sentinel-1 data. The interferogram is consistent with the shallow depth inverted from seismology and confirmed by the presence of surface ruptures. The inversion of multiple InSAR tracks allows characterizing the displacement at depth and along strike on the fault plane. The results are consistent with the focal mechanism derived from seismology. The earthquake has ruptured a 5-km long by ~1.5-km deep fault. The displacement reaches a maximum at a shallow 1 km-depth. The source inverted from InSAR coincides with the Rouvière fault, a branch of the Cévennes fault system formerly known as a normal fault. This reverse earthquake might be an example of an inherited structure re-activation as it is often the case in intraplate regions with polyphased history.</p>

Analyzing the paleoseismic history of the La Rouvière fault, unexpected source of the 11-11-2019, Mw4.9 Le Teil surface rupturing earthquake (Cévennes fault system, France) 

2021 ◽  
Author(s):  
Jean-François Ritz ◽  
Stéphane Baize ◽  
Matthieu Ferry ◽  
Estelle Hannouz ◽  
Magali Riesner ◽  
...  
Keyword(s):  
Normal Fault ◽  
Fault System ◽  
Quaternary Deposits ◽  
Quaternary Period ◽  
Ground Shaking ◽  
Aeolian Deposits ◽  
Reverse Faulting ◽  
History Of ◽  
Region 10 ◽  
First Time

<p>The 11-11-2019 Le Teil earthquake (Mw4.9), located in the Rhône river valley occurred along the La Rouvière fault (LRF) within the NE termination of the Cévennes faults system (CFS). This very shallow moderate magnitude and reverse-faulting event inverted an Oligocene normal fault which was not assessed to be potentially active, causing surface rupture and strong ground shaking. Its morphology shows no evidence of cumulative reverse faulting during the Quaternary. <span><span data-language-to-translate-into="fr" data-phrase-index="0">All of this information raises the question of whether the fault was reactivated for the first time since the Oligocene during the Teil earthquake, </span></span>or if it had broken the surface before, during the Quaternary period, but could not be detected. In addition, it poses the question of the potential reactivation of other faults of the CFS and other faults in metropolitan France as well.</p><p>To tackle those issues, we launched paleoseismic investigations along the LRF to analyze and characterize evidences of paleo-ruptures in Quaternary deposits. Twelve trenches were dug along the section that broke in 2019. The trenches were dug in aeolian deposits and slope colluvium lying against the ancient LRF normal fault mirror carved in the Barremian limestones. Five trenches yielded favorable Quaternary deposits to document deformation suggesting that one paleo-event, maybe more, occurred with kinematic characteristics (sense of movement, amount of displacement) similar to the 2019 event. The radiocarbon dating of the deformed units (“bulks” collected from the colluvium clayey-silty matrix) suggests, in particular, that at least one event occurred in the past 13 Ka (i.e. penultimate event prior to the Teil earthquake) . The fact that these events are not preserved in the morphology is explained by the small amount of displacement and a long return period, consistent with the low strain rate measured by GPS in this region (~10<sup>-9</sup> yrs<sup>-1</sup>). Our study shows that it is therefore fundamental to carry out more detailed paleoseismological investigations in metropolitan France, especially along ancient faults favorably oriented with respect to the present stress field. Those are already planned in the next coming months along other segments of the CFS.</p>

scholarly journals Active faulting, 3-D basin architecture and Plio-Quaternary structural evolution of extensional basins: a 4-D perspective on the central Apennine chain evolution, Italy

2016 ◽  
Author(s):  
Stefano Gori ◽  
Emanuela Falcucci ◽  
Chiara Ladina ◽  
Simone Marzorati ◽  
Fabrizio Galadini
Keyword(s):  
Tectonic Setting ◽  
Structural Evolution ◽  
Normal Fault ◽  
Basin And Range ◽  
Early Pleistocene ◽  
Fault System ◽  
Late Pliocene ◽  
North East ◽  
The North ◽  
Apennine Chain

Abstract. The general “basin and range” aspect of the Apennine relief is generally attributed to the presently active normal fault systems, whose activity throughout the Quaternary is supposed to have created alternating morphological/structural highs and lows. By coupling field geological survey and geophysical investigations, we reconstructed the 3-D geometry of one of the innermost tectonic basins of the central Apennines, the Subequana Valley, bounded to the north-east by an active and seismogenic normal fault. Our analyses revealed that, since the Late Pliocene, the depression experienced a double polarity, half graben-mode nucleation. An early phase, Late Pliocene-Early Pleistocene in age, was led by the ENE-WSW trending and SSE dipping Avezzano-Bussi fault, that determined the formation of an early depocentre towards the N-NW; subsequently, the main fault became the NW-SE trending, SW dipping and presently active normal fault system, that led the formation during the Quaternary of a new fault-related depocentre towards the NE. By considering the available geological information, a similar structural evolution has likely involved three close tectonic basins aligned along the Avezzano-Bussi fault, namely the Fucino basin, the Subequana Valley and the Sulmona basin, and it has been probably experienced by other tectonic basins of the chain. The present work therefore points out that the morpho-tectonic setting of the Apennine chain results from the superposition of deformation events whose “legacy” must be considered in a wider evolutionary perspective. Within this light, our results testify that a simple “basin and range” model – often adopted for morpho-tectonic and kinematic evaluations in active extensional contexts, as in the Apennines – may be actually simplistic, as it could not be applied everywhere, owing to peculiar complexities of the local tectonic histories.

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