Connecting seismicity, gravity-driven erosion and deposition at submarine normal faults: Insights from mapping of the 2004 Mw 6.3 Les Saintes earthquake rupture (French Antilles)

2020 ◽  
Author(s):  
Javier Escartin ◽  
Jeremy Billant ◽  
Frédérique Leclerc ◽  
Jean-Arthur Olive ◽  
Klemen Istenic ◽  
...  
Keyword(s):  
Hanging Wall ◽  
Fault Scarp ◽  
Coseismic Deformation ◽  
Seismic Events ◽  
Fault Rupture ◽  
Mass Wasting ◽  
Erosion And Deposition ◽  
Gravity Driven ◽  
Les Saintes ◽  
Fault Scarps

<p>During the ODEMAR 2013 and SUBSAINTES 2017 cruises we mapped the full extent of the seafloor rupture associated with the 2004 Mw 6.3 Les Saintes extensional earthquake. Near-bottom bathymetry acquired both with ROVs and AUVs along the Roseau Fault reveal a normal fault scarp developing in an extensional graben within the Caribbean volcanic arc, between the islands of Guadeloupe and Dominica. Optical inspection during ROV dives along the scarp’s base, where fault mirrors are well-preserved, allowed us to identify and characterize the coseismic fault rupture, and measure the coseismic displacements using both laser calipers and measurements performed on video-derived, textured 3D models, with accuracies better than 1 cm.</p><p> </p><p>The 2004 rupture extends ~20 km along the Roseau Fault, with a vertical displacement exceeding 2.5 m at its center, and tapering towards its ends. Local variations in apparent fault slip within a single 3D model (fault lengths of ~10 to 300 m) document local deposition of gravity debris cones at the base of the scarp, extending laterally between a few to tens of m, and covering the coseismic markers. Gullies eroding the footwall and depositing debris cones on the hanging wall do not show any significant displacement. Fault scarps on either side of the gully mouth instead record significant displacements, suggesting that either erosion or deposition along the gully bottom efficiently obliterated markers of coseismic deformation.</p><p> </p><p>We inspected all overlapping seafloor imagery acquired in December 2013 and April 2017, >10 years after the 2004 Les Saintes earthquake, extending laterally over >3 km of the Roseau Fault rupture.  Neither the bed of gullies crossing the rupture, nor the debris and rubble at the base of the fault scarp show any noticeable seafloor change indicating mass wasting and transport, and only changes in mobile sediment (e.g., ripples) can be detected between both image sets.  We identified a single area, ~2m wide, with apparent deposition of pebbles during these 3.25 years period, and associated with a local mass-wasting event.</p><p> </p><p>These observations point towards a systematic triggering of mass-wasting during seismic events, with deposition of rubble and rocks both at dejection cones at the mouth of gullies, or at the base of fault scarp sections displaying fault mirrors, covering or obliterating the coseismic markers. Therefore, long-term erosion and deposition processes here are gravity-driven and triggered by the history and magnitude of seismic events. Similar seismic controls may enable denudation of exposed oceanic lithosphere at fault scarps developing along and flanking mid-ocean ridges.</p>

Quantifying submarine mass-wasting and links to seismicity along the Roseau normal fault, Lesser Antilles

2020 ◽  
Author(s):  
Alex Hughes ◽  
Javier Escartín ◽  
Jean-Arthur Olive ◽  
Jeremy Billant ◽  
Christine Deplus ◽  
...  
Keyword(s):  
Sedimentary Cover ◽  
Hanging Wall ◽  
Normal Fault ◽  
Oceanic Lithosphere ◽  
Fault Scarp ◽  
Lesser Antilles ◽  
Mass Wasting ◽  
Erosion And Deposition ◽  
First Order ◽  
Mass Balancing

<p>At the scale of individual faults, few studies have investigated fundamental interactions between active faulting, erosion, and deposition in submarine landscapes dominated by magmatic and volcaniclastic deposits with thin sedimentary cover. Such landscapes comprise a high percentage of the global seafloor. Therefore, there is a significant gap in our understanding of first-order processes of erosion and deposition for a large portion of the Earth’s surface. The paucity of studies derives mainly from challenges involved in the acquisition of high-resolution bathymetry and seafloor data in a deep-marine environment. In this study, we use bathymetry data obtained with autonomous deep-sea vehicles and processed to obtain a 1-m resolution digital elevation model along the active Roseau normal fault, in the Lesser Antilles volcanic arc. The Roseau fault was the source of the 2004 M<sub>w</sub>6.3 Les Saintes earthquake, and M<sub>w </sub>5-6 events are thought to occur on the Roseau fault every few thousand years. Building on the work of Vilaseca (MSc Thesis, 2015), we quantify the height, slope, and volume eroded from a well-defined fault scarp created by the Roseau fault and calculate volumes for a series of erosional footwall catchments developed in the scarp. We also quantify the volume and morphology of a series of dejection cones in the hanging wall of the Roseau fault to facilitate mass-balancing between the hanging wall and footwall of the scarp.</p><p> </p><p>Mass-balancing indicates that in isolated basins, where the primary supply of sediment is from the adjacent footwall scarp, dejection cone volumes are around half of the total volume of material eroded from the individual footwall catchments. Geomorphological analyses show that dejection cones have surface slopes as high as 30°and form as radial depositional features adjacent to catchment outlets. The results of the mass-balancing, the high slope values for the cone surface, and the identification of >1 m sized blocks of eroded material present on the cone surfaces indicate that dejection cones form through episodic, coseismic and/or post-seismic, gravitationally driven mass-wasting of the uplifting footwall scarp. Preliminary morphometric analysis of the Roseau fault scarp potentially indicates that erosion of normal fault scarps in volcaniclastic and magmatic deposits may primarily occur beyond a threshold in fault scarp height between ~40­­–70 m. Above ~40–70 m height, erosional catchments may begin to develop on the footwall scarp and average scarp slope decreases with increasing scarp height until average slope values reach an equilibrium of ~35°. The quantitative survey of the Roseau fault scarp in this study demonstrates that episodic earthquake-related mass-wasting is a key erosional process for volcanic and sedimentary deposits in submarine landscapes. Furthermore, the results presented here will be used as first-order inputs to develop models of seafloor erosion and apply them to understand submarine landscape evolution of the oceanic lithosphere.</p>

scholarly journals The active tectonic landscape of Lake Ohrid (FYR of Macedonia/Albania)

2014 ◽  
Vol 56 (6) ◽  
Author(s):  
Nadine Hoffmann
Keyword(s):  
Active Faults ◽  
Fault Scarp ◽  
Mass Wasting ◽  
Lake Ohrid ◽  
Slip Rates ◽  
Active Tectonic ◽  
Western Border ◽  
Wine Glass ◽  
Yugoslavian Republic ◽  
Fault Scarps

<p><span style="font-family: CMR10; font-size: medium;">The study area at the Lake Ohrid Basin is located on 693 m a.s.l. at the south-western border of the Former Yugoslavian Republic of Macedonia with Albania. It is a suitable location for neotectonic studies. It exhibits a large variety of morphological expressions associated with the seismic activity of the region. Linear bedrock fault scarps give the relief on both sides of the lake a staircase-like appearance; other features are wine-glass shaped valleys and triangular facets. These often short living features are used to identify active faults and to parameterise palaeoearthquakes (slip rates, subsidence and erosion). According to the results of fault scarp profiling a halfgraben shape of the basin is proposed with the west coast being dominated by mass wasting processes most likely triggered by seismic events.</span></p>

scholarly journals Short communication: A semiautomated method for bulk fault slip analysis from topographic scarp profiles

2020 ◽  
Vol 8 (1) ◽  
pp. 211-219
Author(s):  
Franklin D. Wolfe ◽  
Timothy A. Stahl ◽  
Pilar Villamor ◽  
Biljana Lukovic
Keyword(s):  
Monte Carlo ◽  
High Resolution ◽  
Open Source ◽  
Hanging Wall ◽  
Temporal Analysis ◽  
Fault Scarp ◽  
Fault Slip ◽  
Source Characterization ◽  
Wide Range ◽  
Fault Scarps

Abstract. Manual approaches for analyzing fault scarps in the field or with existing software can be tedious and time-consuming. Here, we introduce an open-source, semiautomated, Python-based graphical user interface (GUI) called the Monte Carlo Slip Statistics Toolkit (MCSST) for estimating dip slip on individual or bulk fault datasets that (1) makes the analysis of a large number of profiles much faster, (2) allows users with little or no coding skills to implement the necessary statistical techniques, (3) and provides geologists with a platform to incorporate their observations or expertise into the process. Using this toolkit, profiles are defined across fault scarps in high-resolution digital elevation models (DEMs), and then relevant fault scarp components are interactively identified (e.g., footwall, hanging wall, and scarp). Displacement statistics are calculated automatically using Monte Carlo simulation and can be conveniently visualized in geographic information systems (GISs) for spatial analysis. Fault slip rates can also be calculated when ages of footwall and hanging wall surfaces are known, allowing for temporal analysis. This method allows for the analysis of tens to hundreds of faults in rapid succession within GIS and a Python coding environment. Application of this method may contribute to a wide range of regional and local earthquake geology studies with adequate high-resolution DEM coverage, enabling both regional fault source characterization for seismic hazard and/or estimating geologic slip and strain rates, including creating long-term deformation maps. ArcGIS versions of these functions are available, as well as ones that utilize free, open-source Quantum GIS (QGIS) and Jupyter Notebook Python software.

scholarly journals From coseismic offsets to fault-block mountains

2017 ◽  
Vol 114 (37) ◽  
pp. 9820-9825 ◽  
Author(s):  
George A. Thompson ◽  
Tom Parsons
Keyword(s):  
Upper Mantle ◽  
Hanging Wall ◽  
Large Earthquake ◽  
Western United States ◽  
Coseismic Deformation ◽  
Finite Element Models ◽  
Interferometric Synthetic Aperture Radar ◽  
Normal Faulting ◽  
Gravitational Forces ◽  
Fault Block

In the Basin and Range extensional province of the western United States, coseismic offsets, under the influence of gravity, display predominantly subsidence of the basin side (fault hanging wall), with comparatively little or no uplift of the mountainside (fault footwall). A few decades later, geodetic measurements [GPS and interferometric synthetic aperture radar (InSAR)] show broad (∼100 km) aseismic uplift symmetrically spanning the fault zone. Finally, after millions of years and hundreds of fault offsets, the mountain blocks display large uplift and tilting over a breadth of only about 10 km. These sparse but robust observations pose a problem in that the coesismic uplifts of the footwall are small and inadequate to raise the mountain blocks. To address this paradox we develop finite-element models subjected to extensional and gravitational forces to study time-varying deformation associated with normal faulting. Stretching the model under gravity demonstrates that asymmetric slip via collapse of the hanging wall is a natural consequence of coseismic deformation. Focused flow in the upper mantle imposed by deformation of the lower crust localizes uplift, which is predicted to take place within one to two decades after each large earthquake. Thus, the best-preserved topographic signature of earthquakes is expected to occur early in the postseismic period.

Loading transfer mechanism of a piled raft subjected to normal faulting in sand

2022 ◽  
Vol 12 (1) ◽  
pp. 1-19
Author(s):  
Q. Cai ◽  
B. Xiang ◽  
C. W. W. Ng ◽  
K. S. Wong ◽  
X. Chen ◽  
...  
Keyword(s):  
Finite Difference ◽  
Hanging Wall ◽  
Three Dimensional ◽  
Pile Group ◽  
Transfer Mechanism ◽  
Centrifuge Test ◽  
Fault Rupture ◽  
Normal Faulting ◽  
Compression Failure ◽  
Piled Raft

Although different kinds of foundations have been investigated against an earthquake faulting, the interaction between pile group and dip-slip fault has not yet been fully understood. This letter investigates the interaction between piled raft and normal faulting by means of centrifuge and numerical modelling. In centrifuge test, a piled raft was simulated with a half model for a better observation of fault rupture path under the raft. The loading transfer mechanism was further examined using a three-dimensional finite difference software (FLAC3D). The measured and computed results showed that the piled raft displaced and tilted linearly with the magnitude of faulting. The fault rupture bifurcated into two and diverted towards both edges of the raft. Two types of loading transfer mechanism were identified during faulting. Working load transferred from the raft to the underneath piles, and also from the piles on the side of the hanging wall to the piles on the footwall side, resulting in compression failure of the piles on the footwall side.

Epicentral intensities and damage in the Hebgen Lake, Montana, earthquake of August 17, 1959

1962 ◽  
Vol 52 (2) ◽  
pp. 181-234
Author(s):  
Karl V. Steinbrugge ◽  
William K. Cloud
Keyword(s):  
Ground Motions ◽  
Strong Motion ◽  
Fault Scarp ◽  
Rock Falls ◽  
Small Unit ◽  
The Earth ◽  
Major Fault ◽  
Seismograph Station ◽  
Fault Scarps ◽  
Earth Fill

ABSTRACT An extensive fault scarp system was formed during the Hebgen Lake earthquake of August 17, 1959 (11:37:15 p.m., M.S.T., Gutenberg-Richter magnitude 7.1). Bedrock beneath Hebgen Lake warped, rotated, and caused a seiche in the lake. A major landslide dammed Madison Canyon, causing a lake to form above the slide. An estimated 19 persons were buried by the slide. Other slides and rock falls took out sections of the main highway north of Hebgen Lake and closed many roads in Yellowstone Park. Small unit masonry structures as well as wooden buildings along the major fault scarps usually survived with little damage when subjected only to vibratory forces. The unit masonry buildings, in particular, had little or no earthquake bracing. Intensity at the major scarp has been given a Modified Mercalli Scale rating of X. However, the maximum intensity ratings based on vibratory motion even a few feet away from the scarps were VII or VIII. Within the limits of observation there was little or no reduction in vibratory intensity 5 to 10 miles away compared to that at the fault. This is not to say that the ground motions were similar. At the closest strong-motion seismograph station (Bozeman, 58 miles from the epicenter) maximum recorded acceleration was about 7 per cent gravity. The earthquake was generally felt in about a 600,000 square mile area, mostly north of the instrumental epicenter. The earth-fill Hebgen Dam was within 1000 feet of a major scarp. The dam was significantly damaged, but it continued to be an effective structure.

scholarly journals Exploring the shallow structure of the San Ramón thrust fault in Santiago, Chile (~33.5° S), using active seismic and electric methods

Solid Earth ◽  
2014 ◽  
Vol 5 (2) ◽  
pp. 837-849 ◽  
Author(s):  
D. Díaz ◽  
A. Maksymowicz ◽  
G. Vargas ◽  
E. Vera ◽  
E. Contreras-Reyes ◽  
...  
Keyword(s):  
Seismic Anisotropy ◽  
Average Length ◽  
Sedimentary Cover ◽  
Hanging Wall ◽  
Thrust Fault ◽  
Fault System ◽  
Surface Rupture ◽  
Thrust Tectonics ◽  
Rock Substratum ◽  
Fault Scarps

Abstract. The crustal-scale west-vergent San Ramón thrust fault system, which lies at the foot of the main Andean Cordillera in central Chile, is a geologically active structure with manifestations of late Quaternary complex surface rupture on fault segments along the eastern border of the city of Santiago. From the comparison of geophysical and geological observations, we assessed the subsurface structural pattern that affects the sedimentary cover and rock-substratum topography across fault scarps, which is critical for evaluating structural models and associated seismic hazard along the related faults. We performed seismic profiles with an average length of 250 m, using an array of 24 geophones (Geode), with 25 shots per profile, to produce high-resolution seismic tomography to aid in interpreting impedance changes associated with the deformed sedimentary cover. The recorded travel-time refractions and reflections were jointly inverted by using a 2-D tomographic approach, which resulted in variations across the scarp axis in both the velocities and the reflections that are interpreted as the sedimentary cover-rock substratum topography. Seismic anisotropy observed from tomographic profiles is consistent with sediment deformation triggered by west-vergent thrust tectonics along the fault. Electrical soundings crossing two fault scarps were used to construct subsurface resistivity tomographic profiles, which reveal systematic differences between lower resistivity values in the hanging wall with respect to the footwall of the geological structure, and clearly show well-defined east-dipping resistivity boundaries. These boundaries can be interpreted in terms of structurally driven fluid content change between the hanging wall and the footwall of the San Ramón fault. The overall results are consistent with a west-vergent thrust structure dipping ~55° E in the subsurface beneath the piedmont sediments, with local complexities likely associated with variations in fault surface rupture propagation, fault splays and fault segment transfer zones.

scholarly journals Analysis of Petrinja 2020 Earthquake (Croatia) and First 500 Aftershocks >M1.0, Identification of Their Sources and Seismogenic Faults

2021 ◽  
Author(s):  
Tihomir Marjanac ◽  
Marina Čalogović ◽  
Karlo Bermanec ◽  
Ljerka Marjanac
Keyword(s):  
Hanging Wall ◽  
Normal Fault ◽  
Seismic Energy ◽  
Seismic Events ◽  
Surface Cracks ◽  
Surface Phenomena ◽  
Slip Mechanism ◽  
Seismogenic Faults ◽  
Water Activation ◽  
Major Fault

Abstract Strong earthquake of M6.4 stroke Petrinja and neighbouring cities of Sisak and Glina in Croatia on December 29th 2020. It was preceded by two foreshocks of M5.2 and M5.0, and followed by a series of aftershocks of various magnitudes and intensities. We have analysed first 500 earthquakes and aftershocks of > M1.0 which occurred from December 28th 2020 to January 19th 2021, their frequency, focal depths, and coseismic surface phenomena. Correlation of focal depths revealed the source of earthquakes was faulting of hanging wall of a listric normal fault with NW-SE strike and dip towards NE. Major fault seems to have caused earthquakes with only minor magnitudes. The strongest two earthquakes of M6.4 and M5.2 were initiated on synthetic fault, whereas M5.0 earthquake was initiated on an antithetic fault. Almost 50% of all seismic energy of the first 500 analysed seismic events over M1.0 was released on 1 km and 10 km deep hypocentres. Focal mechanisms of major earthquakes and strong fore- and aftershocks indicate dextral-slip mechanism, which is also in accordance with the orientation of surface cracks, land faulting and sand volcano trains. Co-seismic surface phenomena are land cracks and fissures, land faults, sand volcanoes, eruptive springing of ground water, activation of landslides, and formation of dozens of collapse sinkholes which continued to form and grow for about a month following the major earthquake.

scholarly journals Coseismic Deformation Field of the Mw 7.3 12 November 2017 Sarpol-e Zahab (Iran) Earthquake: A Decoupling Horizon in the Northern Zagros Mountains Inferred from InSAR Observations

2018 ◽  
Vol 10 (10) ◽  
pp. 1589 ◽  
Author(s):  
Sanaz Vajedian ◽  
Mahdi Motagh ◽  
Zahra Mousavi ◽  
Khalil Motaghi ◽  
Eric. Fielding ◽  
...  
Keyword(s):  
Hanging Wall ◽  
Source Model ◽  
Lateral Spreading ◽  
Maximum Amount ◽  
Coseismic Deformation ◽  
Past Century ◽  
Zagros Mountains ◽  
Tectonically Active ◽  
Northern Portion ◽  
Progressive Scan

The study of crustal deformation fields caused by earthquakes is important for a better understanding of seismic hazard and growth of geological structures in tectonically active areas. In this study, we present, using interferometric measurements constructed from Sentinel-1 Terrain Observation with Progressive Scan (TOPS) data and ALOS-2 ScanSAR, coseismic deformation and source model of the Mw 7.3, 12 November 2017 earthquake that hit northwest of the Zagros Mountains in the region between Iran–Iraq border. This was one of the strongest seismic events to hit this region in the past century, and it resulted in an uplift area of about 3500 km2 between the High Zagros Fault (HZF) and Mountain Front Fault (MFF) with a maximum amount of 70 cm south of Miringe fault. A subsidence over an area of 1200 km2 with a maximum amount of 35 cm occurred near Vanisar village at the hanging wall of the HZF. Bayesian inversion of interferometric synthetic aperture radar (InSAR) observations suggests a source model at a depth between 14 and 20 km that is consistent with the existence of a decoupling horizon southwest edge of the northern portion of the Zagros Mountains near the MFF. Moreover, we present evidence for a number of coseismically induced rockslides and landslides, the majority of them which occurred along or close to pre-existing faults, causing decorrelation in differential interferograms. Exploiting the offset-tracking technique, we estimated surface motion by up to 34 and 10 m in horizontal and vertical directions, respectively, due to lateral spreading on a big coseismic-induced landslide near Mela-Kabod. Field observations also revealed several zones of en echelon fractures and crack zones developed along a pre-existing fault passing through Qasr-e Shirin City, which exhibited secondary surface slip by up to 14 cm along its strike.

scholarly journals Short communication: A semi-automated method for rapid fault slip analysis from topographic scarp profiles

2019 ◽  
Author(s):  
Franklin D. Wolfe ◽  
Timothy A. Stahl ◽  
Pilar Villamor ◽  
Biljana Lukovic
Keyword(s):  
Monte Carlo ◽  
High Resolution ◽  
Open Source ◽  
Hanging Wall ◽  
Temporal Analysis ◽  
Fault Scarp ◽  
Fault Slip ◽  
Source Characterization ◽  
Automated Method ◽  
Wide Range

Abstract. Here, we introduce an open source, semi-automated, Python-based graphical user interface (GUI) called the Monte Carlo Slip Statistics Toolkit (MCSST) for estimating dip slip on individual or bulk fault datasets. Using this toolkit, profiles are defined across fault scarps in high-resolution digital elevation models (DEMs) and then relevant fault scarp components are interactively identified (e.g., footwall, hanging wall, and scarp). Displacement statistics are calculated automatically using Monte Carlo simulation and can be conveniently visualized in Geographic Information Systems (GIS) for spatial analysis. Fault slip rates can also be calculated when ages of footwall and hanging wall surfaces are known, allowing for temporal analysis. This method allows for rapid analysis of tens to hundreds of faults in rapid succession within GIS and a Python coding environment. Application of this method may contribute to a wide range of regional and local earthquake geology studies with adequate high-resolution DEM coverage, both regional fault source characterization for seismic hazard and/or estimating geologic slip and strain rates, including creating long-term deformation maps. ArcGIS versions of these functions are available, as well ones that utilize free, open source Quantum GIS (QGIS) and Jupyter Notebook Python software.

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