Practicality of Monitoring Crustal Deformation Processes in Subduction Zones by Seafloor and Inland Networks of Seismological Observations

The uplift and evolution of a noncollisional orogen developed along a subduction zone, such as the Andean system, is a direct consequence of the interrelation between plate tectonic stresses and erosion. Tectonic stresses are related to the convergence velocity and thermal state, among other causes. In this paper, a new model designed to investigate the evolution of the topography and the upper crustal deformation of noncollisional orogens in a subduction zone produced by the oceanic crust being subducted is presented. The mechanical behavior of the crust was modeled by means of finite elements methods to solve Stokes equations for a strain-rate-dependent viscoplastic rheology. The model takes into account erosion effects using interface-tracking methods to assign fictitious properties to nonmaterial elements.

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The West Crati Fault, Calabria (southern Italy): refined crustal extension rates constrained by geologic and GPS data.

10.5194/egusphere-egu21-2279 ◽

2021 ◽

Author(s):

Marco Meschis ◽

Susanna Zerbini ◽

Giovanni Lattanzi ◽

Miriana Di Donato ◽

Silvia Castellaro

Keyword(s):

Subduction Zone ◽

Crustal Deformation ◽

Subduction Zones ◽

Southern Italy ◽

Gps Data ◽

Short Term ◽

The West ◽

Marine Terraces ◽

Uplift Rates ◽

Different Time Scales

Geologic studies of preserved stairs-like uplifted marine terraces and continuous GPS data collected in subduction zones provide a unique opportunity to investigate, on different time scales, crustal deformation resulting from upper&#8208;plate extension. The West Crati Fault in Calabria, southern Italy, is a normal fault located within the seismically extending upper plate above the Ionian subduction zone. It is of interest because a thorough comparison of the extension rates inferred from geologic and GPS data has not yet been performed. This E-dipping fault lies in an area where a few historical damaging earthquakes occurred, examples are those in 1184 (M 6.7) and 1638 (M 6.7). Fault slip-rates and earthquake recurrence intervals for the West Crati fault are still subject of debate. We investigated raised marine terraces along the strike of the fault, on its footwall over its tips, located above the Ionian subduction zone, to derive refined uplift rates and study the role that known extensional faults contribute to observed coastal uplift. We also estimated short-term vertical and horizontal movements on the hangingwall of this fault by analyzing the data of 7 permanent GPS stations located along the N-S oriented strike of this fault.Our preliminary results demonstrate that (i) GIS-based elevations of Middle to Late Pleistocene marine terraces, as well as temporally constant uplift rates, vary along the strike of this fault, mapped on its footwall; (ii) rates of short-term vertical movements vary along the strike of this fault on its hangingwall. This confirms active deformation, on different time scales, along the E-dipping West Crati Fault, suggesting that the fault slip-rate governing seismic hazard has also been constant through time. Our preliminary results show the importance of mapping crustal deformation within the upper plate above subduction zones to avoid unreliable interpretations concerning the mechanism responsible for regional uplift.

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The Fate of Subduction Fluids above the Subduction Interface: Implications for Mantle Wedge Deformation Processes

10.5194/egusphere-egu2020-9555 ◽

2020 ◽

Author(s):

Samuel Angiboust ◽

Johannes Glodny ◽

Aitor Cambeses ◽

Tom Raimondo ◽

Patrick Monié ◽

...

Keyword(s):

Subduction Zones ◽

Hanging Wall ◽

Plate Interface ◽

Rock Interaction ◽

Multi Scale ◽

Hp Metamorphism ◽

Elastic Loading ◽

Deformation Processes ◽

Subduction Fluids ◽

Shed Light

The physical and mechanical processes rooted in the hydrated, serpentinized mantle above subduction zones (the &#8220;cold nose&#8221;) remain debated and poorly understood, despite fundamental consequences on the elastic loading of the seismogenic interface. The fluids crossing this interface are expected to generate nests of seismicity and at the same time weaken the interface hanging wall through serpentinization and metasomatic processes. Ultramafic and jadeitite samples from two natural laboratories where such fossil settings are now visible at the Earth&#8217;s surface are used here to document multi-scale deformation mechanisms and fluid-rock interaction processes. Field relationships enable tracking the pathways followed by the fluids during HP metamorphism. Petrographic, geochemical, geochronological and microstructural observations demonstrate the complex interplay between brittle and plastic deformation processes throughout the gradual hydration of the cold nose mantle over millions of years. Changes in bulk rock geochemical and paragenetic sequence also reveal the evolution of the composition of the fluid source through time. These results shed light on the geometry of the cold nose above the interface, with implications for volatile budget estimates, rheology of the plate interface (including the various types of seismicity) as well as the interpretation of Vp/Vs ratios from active subduction settings worldwide.

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Unique deformation processes involving the recrystallization of chrysotile within serpentinite: implications for aseismic slip events within subduction zones

Terra Nova ◽

10.1111/j.1365-3121.2007.00771.x ◽

2007 ◽

Vol 19 (6) ◽

pp. 454-461 ◽

Cited By ~ 14

Author(s):

Ken-ichi Hirauchi ◽

Haruka Yamaguchi

Keyword(s):

Subduction Zones ◽

Aseismic Slip ◽

Deformation Processes

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Understanding the Origin and Mixing of Deep Fluids in Shallow Aquifers and Possible Implications for Crustal Deformation Studies: San Vittorino Plain, Central Apennines

Applied Sciences ◽

10.3390/app11041353 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1353

Author(s):

Marino Domenico Barberio ◽

Francesca Gori ◽

Maurizio Barbieri ◽

Tiziano Boschetti ◽

Antonio Caracausi ◽

...

Keyword(s):

Cross Sections ◽

Crustal Deformation ◽

Central Italy ◽

Circulation Model ◽

Aquifer Systems ◽

Groundwater Circulation ◽

Deformation Processes ◽

Geological Map ◽

Gas Interactions ◽

Seismic Area

Expanding knowledge about the origin and mixing of deep fluids and the water–rock–gas interactions in aquifer systems can represent an improvement in the comprehension of crustal deformation processes. An analysis of the deep and meteoric fluid contributions to a regional groundwater circulation model in an active seismic area has been carried out. We performed two hydrogeochemical screenings of 15 springs in the San Vittorino Plain (central Italy). Furthermore, we updated the San Vittorino Plain structural setting with a new geological map and cross-sections, highlighting how and where the aquifers are intersected by faults. The application of Na-Li geothermometers, coupled with trace element and gas analyses, agrees in attributing the highest temperatures (>150 °C), the greatest enrichments in Li (124.3 ppb) and Cs (>5 ppb), and traces of mantle-derived He (1–2%) to springs located in correspondence with high-angle faults (i.e., S5, S11, S13, and S15). This evidence points out the role of faults acting as vehicles for deep fluids into regional carbonate aquifers. These results highlight the criteria for identifying the most suitable sites for monitoring variations in groundwater geochemistry due to the uprising of deep fluids modulated by fault activity to be further correlated with crustal deformation and possibly with seismicity.

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