scholarly journals Mixed-Mode Slip Behavior of the Altotiberina Low-Angle Normal Fault System (Northern Apennines, Italy) through High-Resolution Earthquake Locations and Repeating Events

2017 ◽  
Vol 122 (12) ◽  
pp. 10,220-10,240 ◽  
Author(s):  
Luisa Valoroso ◽  
Lauro Chiaraluce ◽  
Raffaele Di Stefano ◽  
Giancarlo Monachesi
Keyword(s):  
High Resolution ◽  
Mixed Mode ◽  
Normal Fault ◽  
Northern Apennines ◽  
Fault System ◽  
Earthquake Locations

scholarly journals Localized extension in megathrust hanging wall following great earthquakes in western Nepal

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Magali Riesner ◽  
Laurent Bollinger ◽  
Judith Hubbard ◽  
Cyrielle Guérin ◽  
Marthe Lefèvre ◽  
...  
Keyword(s):  
High Resolution ◽  
Hanging Wall ◽  
Ground Surface ◽  
Normal Fault ◽  
Fault Scarp ◽  
Fault System ◽  
Digital Elevation ◽  
Thrust Zone ◽  
Elevation Model ◽  
Short Time

AbstractThe largest (M8+) known earthquakes in the Himalaya have ruptured the upper locked section of the Main Himalayan Thrust zone, offsetting the ground surface along the Main Frontal Thrust at the range front. However, out-of-sequence active structures have received less attention. One of the most impressive examples of such faults is the active fault that generally follows the surface trace of the Main Boundary Thrust (MBT). This fault has generated a clear geomorphological signature of recent deformation in eastern and western Nepal, as well as further west in India. We focus on western Nepal, between the municipalities of Surkhet and Gorahi where this fault is well expressed. Although the fault system as a whole is accommodating contraction, across most of its length, this particular fault appears geomorphologically as a normal fault, indicating crustal extension in the hanging wall of the MHT. We focus this study on the reactivation of the MBT along the Surkhet-Gorahi segment of the surface trace of the newly named Reactivated Boundary Fault, which is ~ 120 km long. We first generate a high-resolution Digital Elevation Model from triplets of high-resolution Pleiades images and use this to map the fault scarp and its geomorphological lateral variation. For most of its length, normal motion slip is observed with a dip varying between 20° and 60° and a maximum cumulative vertical offset of 27 m. We then present evidence for recent normal faulting in a trench located in the village of Sukhetal. Radiocarbon dating of detrital charcoals sampled in the hanging wall of the fault, including the main colluvial wedge and overlying sedimentary layers, suggest that the last event occurred in the early sixteenth century. This period saw the devastating 1505 earthquake, which produced ~ 23 m of slip on the Main Frontal Thrust. Linked or not, the ruptures on the MFT and MBT happened within a short time period compared to the centuries of quiescence of the faults that followed. We suggest that episodic normal-sense activity of the MBT could be related to large earthquakes rupturing the MFT, given its proximity, the sense of motion, and the large distance that separates the MBT from the downdip end of the locked fault zone of the MHT fault system. We discuss these results and their implications for the frontal Himalayan thrust system.

Basement-controlled Neogene polyphase cover thrusting and basin development along the Chianti Mountains ridge (Northern Apennines, Italy)

1999 ◽  
Vol 136 (2) ◽  
pp. 133-152 ◽  
Author(s):  
MARCO BONINI
Keyword(s):  
Sedimentary Cover ◽  
Normal Fault ◽  
Northern Apennines ◽  
Fault System ◽  
Time Interval ◽  
Tectonic Structures ◽  
Quaternary Period ◽  
Deformation Stages ◽  
Thrust System ◽  
Continental Basin

The Chianti Mountains is an important sector of an E-verging regional thrust-related fold (the so-called Tuscan Nappe) extending along the whole length of the Northern Apennines. This thrust system involves the Tuscan Sequence superposing the Macigno sandstones onto Cervarola-Falterona sandstones, both of which are sedimented in adjacent foredeep basins. Detailed field mapping and analysis of superposition relations among tectonic structures, as well as correlation between structures and syntectonic deposition, has allowed Chianti Mountain evolution to be interpreted in terms of three main stages of deformation.The D1 stage resulted in the NE-directed synsedimentary thrusting of the Macigno onto the Cervarola-Falterona sandstones, while large NE to ENE-vergent thrust-related folds developed during the two successive deformation stages (D2 and D3). Fault-propagation folds developed during the D2 stage, and were affected by the Main Chianti Mountains Thrust (MCMT) during the successive D3 stage. In particular, the D3 stage has been correlated to the development, during the Pliocene period, of the hinterland Upper Valdarno Basin, which was previously considered to be an extensional basin. In fact, this continental basin formed along the eastern margin of the Chianti Mountains, ahead of the MCMT that also produced a shortening of the basin fill. With the beginning of the Quaternary period, the tectonic regime switched to extensional, as manifested by the development of a normal fault system on the opposite basin margin.The data presented here allow us to infer that the Chianti Mountains thrust system (D2 and D3) developed during a time interval spanning from the Late Miocene (∼12 Ma) until the Late Pliocene (∼2 Ma) periods. In the Northern Apennines, polyphase thrusting recorded by cover rocks has been related to the activity of basement thrusts, which have been recently evidenced by geophysical data. In this context, the two latest stages of deformation recognised in the Chianti Mountains have been attributed to the activity of the Abetone–Cetona crustal thrust, the deformational effects of which propagated forward in the sedimentary cover.

Extensional deformation structures within a convergent orogen: The Val di Lima low-angle normal fault system (Northern Apennines, Italy)

2014 ◽  
Vol 66 ◽  
pp. 205-222 ◽  
Author(s):  
Luca Clemenzi ◽  
Giancarlo Molli ◽  
Fabrizio Storti ◽  
Philippe Muchez ◽  
Rudy Swennen ◽  
...  
Keyword(s):  
Normal Fault ◽  
Northern Apennines ◽  
Fault System ◽  
Extensional Deformation ◽  
Deformation Structures

A deep resistivity Full Waver survey unravels the 3D structure of the Castelluccio basin in relation to the source of the 2016 Mw 6.5 Norcia earthquake (central Italy)

2020 ◽  
Author(s):  
Vincenzo Sapia ◽  
Fabio Villani ◽  
Federico Fischanger ◽  
Matteo Lupi ◽  
Paola Baccheschi ◽  
...  
Keyword(s):  
High Resolution ◽  
Spatial Scales ◽  
Sedimentary Cover ◽  
Central Italy ◽  
3D Structure ◽  
Normal Fault ◽  
Fault System ◽  
High Resistivity ◽  
Low Resistivity ◽  
Regularized Inversion

<p>The Castelluccio basin in the central Apennines (Italy) is a ~20-km<sup>2</sup>-wide intramontane Quaternary depression located in the hangingwall of the NW-trending and SW-dipping Vettore-Bove normal fault system (VBFS). This system is responsible for the 2016-2017 seismic sequence, culminated with the 30 October 2016 Mw 6.5 Norcia earthquake that caused widespread surface faulting affecting also the northern part of the Castelluccio basin. Available borehole and geophysical data are not enough to constrain the basin structure, infill architecture and their relations with the long-term activity of the VBFS. Therefore, we carried out an extensive 3D survey using the innovative Fullwaver (FW) technology, conceived to perform deep electrical resistivity tomography (DERT). We aimed at: a) mapping the geometry of the pre-Quaternary limestone basement and the basin infill thickness down to a depth of ~1 km; b) mapping the subsurface structure of known faults and their extent underneath the alluvial cover; c) mapping possible blind faults splays.</p><p>The 3D survey covered a 23 km<sup>2 </sup>area and it was designed with the aim to map the region as regularly as possible, taking into account the rugged topography and logistic issues. We used a series of independent 2-channels receivers connected each to three grounded steel electrodes, 200 m spaced, to record the electrical field generated by a five kilowatt current regulated Time Domain Induced Polarization transmitter. Data were modelled with ViewLab software via a regularized inversion with smoothness constraints to cope with the expected subsurface strong resistivity changes, and to obtain a robust 3D resistivity model.</p><p>The FW technology allowed us to constrain the geometry of the basin. The infill material is imaged as a wide, N-trending moderately resistive (< 300 Ωm) to conductive  (< 100 Ωm) region, likely made of silty sands and gravels, deepening down to 500 m b.g.l. in the southern sector, suggesting the occurrence of two main depocenters. All over the basin, we identify paired high-resistivity (> 500-1000 Ωm) and low-resistivity (< 400 Ωm) belts related to the limestone basement and to the basin infill, respectively. They display NNE and NNW dominant trends. We interpret the sharp boundaries of NNE-trending belts as related to early extensional faults promoting the basin inception. The NNW-trending belts suggest the occurrence of faults that locally cross-cut the previous ones, and that we interpret as splays of the VBFS buried under the basin sedimentary cover. The recognition of different systems of extensional faults is coherent with results of high-resolution seismic profiling carried out recently in the basin. A high-resolution 2D transect with 15 m-spaced electrodes across the 2016 surface ruptures shows details of the active VBFS splay down to 300 m depth. Moreover, in the eastern sector of the survey area, low-resistivity round-shaped anomalies in the Mesozoic substratum hints for deep Miocene compressional structures. Therefore, our DERT imaging suggests a complex tectonics in the subsurface of the Norcia earthquake fault. In particular, the currently active NNW-trending faults seem to overprint a pre-existing structural framework, promoting fault segmentation at different spatial scales</p>

scholarly journals On the mechanical behaviour of a low-angle normal fault: the Alto Tiberina fault (Northern Apennines, Italy) system case study

Solid Earth ◽  
2016 ◽  
Vol 7 (6) ◽  
pp. 1537-1549 ◽  
Author(s):  
Luigi Vadacca ◽  
Emanuele Casarotti ◽  
Lauro Chiaraluce ◽  
Massimo Cocco
Keyword(s):  
Mechanical Behaviour ◽  
Hanging Wall ◽  
Normal Fault ◽  
Active Role ◽  
Northern Apennines ◽  
Fault System ◽  
Tectonically Active ◽  
Main Fault ◽  
Microseismic Activity ◽  
High Degree

Abstract. Geological and seismological observations have been used to parameterize 2-D numerical elastic models to simulate the interseismic deformation of a complex extensional fault system located in the Northern Apennines (Italy). The geological system is dominated by the presence of the Alto Tiberina fault (ATF), a large (60 km along strike) low-angle normal fault dipping 20° in the brittle crust (0–15 km).  The ATF is currently characterized by a high and constant rate of microseismic activity, and no moderate-to-large magnitude earthquakes have been associated with this fault in the past 1000 years. Modelling results have been compared with GPS data in order to understand the mechanical behaviour of this fault and a suite of minor syn- and antithetic normal fault segments located in the main fault hanging wall. The results of the simulations demonstrate the active role played by the Alto Tiberina fault in accommodating the ongoing tectonic extension in this sector of the chain. The GPS velocity profile constructed through the fault system cannot be explained without including the ATF's contribution to deformation, indicating that this fault, although misoriented, has to be considered tectonically active and with a creeping behaviour below 5 km depth. The low-angle normal fault also shows a high degree of tectonic coupling with its main antithetic fault (the Gubbio fault), suggesting that creeping along the ATF may control the observed strain localization and the pattern of microseismic activity.

scholarly journals On the mechanical behaviour of a low angle normal fault: the Altotiberina fault (Northern Apennines, Italy) system case study

2016 ◽  
Author(s):  
Luigi Vadacca ◽  
Emanuele Casarotti ◽  
Lauro Chiaraluce ◽  
Massimo Cocco
Keyword(s):  
Mechanical Behaviour ◽  
Numerical Models ◽  
Hanging Wall ◽  
Normal Fault ◽  
Active Role ◽  
Northern Apennines ◽  
Fault System ◽  
Tectonically Active ◽  
Main Fault ◽  
Microseismic Activity

Abstract. Geological and seismological observations have been used to parameterize 2D numerical models to simulate the interseismic deformation of a complex extensional fault system located in the Northern Apennines (Italy). The geological system is dominated by the presence of the Altotiberina fault (ATF), a large (60 km along strike) low-angle normal fault 20° dipping in the brittle crust (0–15 km). The ATF is currently interested by a high and constant rate of microseismic activity and no moderate-to-large magnitude earthquakes have been associated to it for the past 1000 years. Modelling results have been compared with GPS data in order to understand the mechanical behaviour of this fault and a suite of minor syn- and antithetic normal fault segments located in the main fault hanging-wall. The results of the simulations demonstrate the active role played by the Altotiberina fault in accommodating the on going tectonic extension in this sector of the chain. The GPS velocity profile constructed through the fault system cannot be explained without including the ATF's contribution to deformation, indicating that this fault although misoriented has to be considered tectonically active and with a creeping behaviour below 5 km of depth. The low angle normal fault also shows a high degree of tectonic coupling with its main antithetic fault (the Gubbio fault) suggesting that creeping along the ATF may control the observed strain localization and the pattern of microseismic activity.

scholarly journals High-resolution surface faulting from the 1983 Idaho Lost River Fault Mw 6.9 earthquake and previous events

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Simone Bello ◽  
Chelsea P. Scott ◽  
Federica Ferrarini ◽  
Francesco Brozzetti ◽  
Tyler Scott ◽  
...  
Keyword(s):  
High Resolution ◽  
Scaling Laws ◽  
Normal Fault ◽  
Fault System ◽  
Pixel Resolution ◽  
High Resolution Mapping ◽  
Digital Elevation ◽  
Aerial Vehicle ◽  
Resolution Mapping ◽  
Fault Length

AbstractWe present high-resolution mapping and surface faulting measurements along the Lost River fault (Idaho-USA), a normal fault activated in the 1983 (Mw 6.9) earthquake. The earthquake ruptured ~35 km of the fault with a maximum throw of ~3 m. From new 5 to 30 cm-pixel resolution topography collected by an Unmanned Aerial Vehicle, we produce the most comprehensive dataset of systematically measured vertical separations from ~37 km of fault length activated by the 1983 and prehistoric earthquakes. We provide Digital Elevation Models, orthophotographs, and three tables of: (i) 757 surface rupture traces, (ii) 1295 serial topographic profiles spaced 25 m apart that indicate rupture zone width and (iii) 2053 vertical separation measurements, each with additional textual and numerical fields. Our novel dataset supports advancing scientific knowledge about this fault system, refining scaling laws of intra-continental faults, comparing to other earthquakes to better understand faulting processes, and contributing to global probabilistic hazard approaches. Our methodology can be applied to other fault zones with high-resolution topographic data.

scholarly journals Radiography of a normal fault system by 64,000 high-precision earthquake locations: The 2009 L'Aquila (central Italy) case study

2013 ◽  
Vol 118 (3) ◽  
pp. 1156-1176 ◽  
Author(s):  
L. Valoroso ◽  
L. Chiaraluce ◽  
D. Piccinini ◽  
R. Di Stefano ◽  
D. Schaff ◽  
...  
Keyword(s):  
High Precision ◽  
Central Italy ◽  
Normal Fault ◽  
Fault System ◽  
Earthquake Locations
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