scholarly journals Effect of regional tectonic setting on local fault response to episodes of volcanic activity

2007 ◽  
Vol 34 (13) ◽  
pp. n/a-n/a ◽  
Author(s):  
Diana C. Roman ◽  
Philip Heron
Keyword(s):  
Volcanic Activity ◽  
Tectonic Setting ◽  
Regional Tectonic

scholarly journals New seismological data from the Calabrian arc reveal arc-orthogonal extension across the subduction zone

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tiziana Sgroi ◽  
Alina Polonia ◽  
Graziella Barberi ◽  
Andrea Billi ◽  
Luca Gasperini
Keyword(s):  
Lateral Displacement ◽  
Tectonic Setting ◽  
Plate Boundary ◽  
Velocity Model ◽  
Tectonic Deformation ◽  
Accretionary Wedge ◽  
Tectonic Structures ◽  
Plate Convergence ◽  
Seismogenic Layer ◽  
Regional Tectonic

AbstractThe Calabrian Arc subduction-rollback system along the convergent Africa/Eurasia plate boundary is among the most active geological structures in the Mediterranean Sea. However, its seismogenic behaviour is largely unknown, mostly due to the lack of seismological observations. We studied low-to-moderate magnitude earthquakes recorded by the seismic network onshore, integrated by data from a seafloor observatory (NEMO-SN1), to compute a lithospheric velocity model for the western Ionian Sea, and relocate seismic events along major tectonic structures. Spatial changes in the depth distribution of earthquakes highlight a major lithospheric boundary constituted by the Ionian Fault, which separates two sectors where thickness of the seismogenic layer varies over 40 km. This regional tectonic boundary represents the eastern limit of a domain characterized by thinner lithosphere, arc-orthogonal extension, and transtensional tectonic deformation. Occurrence of a few thrust-type earthquakes in the accretionary wedge may suggest a locked subduction interface in a complex tectonic setting, which involves the interplay between arc-orthogonal extension and plate convergence. We finally note that distribution of earthquakes and associated extensional deformation in the Messina Straits region could be explained by right-lateral displacement along the Ionian Fault. This observation could shed new light on proposed mechanisms for the 1908 Messina earthquake.

Cumulates and gabbros in southern Albanian ophiolites: their bearing on regional tectonic setting

2006 ◽  
Vol 260 (1) ◽  
pp. 267-299 ◽  
Author(s):  
F. Koller ◽  
V. Hoeck ◽  
T. Meisel ◽  
C. Ionescu ◽  
K. Onuzi ◽  
...  
Keyword(s):  
Tectonic Setting ◽  
Regional Tectonic

scholarly journals Volcanic activity and gas emissions along the South Sandwich Arc

2020 ◽  
Vol 83 (1) ◽  
Author(s):  
Emma J. Liu ◽  
Kieran Wood ◽  
Alessandro Aiuppa ◽  
Gaetano Giudice ◽  
Marcello Bitetto ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Volcanic Activity ◽  
Emission Rate ◽  
Tectonic Setting ◽  
Hydrothermal Systems ◽  
Molar Ratio ◽  
The South ◽  
Gas Emissions ◽  
Volcanic Arc

AbstractThe South Sandwich Volcanic Arc is one of the most remote and enigmatic arcs on Earth. Sporadic observations from rare cloud-free satellite images—and even rarer in situ reports—provide glimpses into a dynamic arc system characterised by persistent gas emissions and frequent eruptive activity. Our understanding of the state of volcanic activity along this arc is incomplete compared to arcs globally. To fill this gap, we present here detailed geological and volcanological observations made during an expedition to the South Sandwich Islands in January 2020. We report the first in situ measurements of gas chemistry, emission rate and carbon isotope composition from along the arc. We show that Mt. Michael on Saunders Island is a persistent source of gas emissions, releasing 145 ± 59 t day−1 SO2 in a plume characterised by a CO2/SO2 molar ratio of 1.8 ± 0.2. Combining this CO2/SO2 ratio with our independent SO2 emission rate measured near simultaneously, we derive a CO2 flux of 179 ± 76 t day−1. Outgassing from low temperature (90–100 °C) fumaroles is pervasive at the active centres of Candlemas and Bellingshausen, with measured gas compositions indicative of interaction between magmatic fluids and hydrothermal systems. Carbon isotope measurements of dilute plume and fumarole gases from along the arc indicate a magmatic δ13C of − 4.5 ± 2.0‰. Interpreted most simply, this result suggests a carbon source dominated by mantle-derived carbon. However, based on a carbon mass balance from sediment core ODP 701, we show that mixing between depleted upper mantle and a subduction component composed of sediment and altered crust is also permissible. We conclude that, although remote, the South Sandwich Volcanic Arc is an ideal tectonic setting in which to explore geochemical processes in a young, developing arc.

scholarly journals Petrogenesis of Volcanic Arc Granites from Bayah Complex, Banten, Indonesia

2019 ◽  
Vol 4 (2) ◽  
pp. 104
Author(s):  
Jemi Saputra Ahnaf ◽  
Aton Patonah ◽  
Haryadi Permana
Keyword(s):  
Tectonic Setting ◽  
Crustal Contamination ◽  
Polarized Light ◽  
Granitic Rocks ◽  
Tectonic Activity ◽  
Molar Ratio ◽  
Petrographic Analysis ◽  
Volcanic Arc ◽  
Regional Tectonic ◽  
Type Granite

This research aimed to reveal the petrogenesis of granitic rocks of Bayah Complex starting from magma differentiation to exposing event, this research also intended to determine the tectonic environment. The methods carried out in this research include field observation, petrographic analysis using polarized light microscopy, and geochemical analysis using X-Ray Fluorescence (XRF) and Inductively Coupled Mass Spectrometry (ICP-MS). Petrographic analysis shows that Bayah granitic rocks are composed of quartz, plagioclase, and K-feldspar while the rest are amphibole, biotite, sericite, chlorite, epidote, and opaque. Based on its major oxide concentrations, Bayah granitic rocks classified as granite and diorite-quartz which have high-K calc-alkaline magma. 4 samples of granitic rocks showed the A/N+K+C > 1 molar ratios belonging to the peraluminous S-type granite index while the remaining 1 sample showed a molar ratio of A/N+ K+C < 1 and A/N+K > 1 which classified as metaluminous I-type granite. Accordingly, Bayah granitic rocks are S-type granite which crystallized from sediment-derived magma, the sediments itself estimated sourced from continental especially Malay Peninsula, Indonesian Tin Island, and Schwaner Mountains. During differentiation, the magma undergone crustal contamination reflected by the increase in both SiO2 0.51 wt% and Al2O3 1.95 wt%, and decrease in Fe2O3 + MgO 0.61 wt% from the pure composition of sediment-derived magma. Furthermore, the occurrence of crustal contamination also recognized from high concentrations of Rb and Ba which indicate the interaction of magma with the materials of continental crust. Regard to the exposing event, Bayah granitic rocks approximated to be exposed due to regional tectonic activity which caused Orogenesa I in the Early Oligocene to the Late Oligocene. Moreover, based on the plot of trace elements especially Rb, Y, Nb, Ta, and Yb on Harker and tectonic discriminant diagrams, Bayah granitic rocks are formed on volcanic-arc active continental margins in accordance with regional tectonic setting.           

The San Salvador earthquake of May 3, 1965

1966 ◽  
Vol 56 (2) ◽  
pp. 561-575
Author(s):  
Cinna Lomnitz ◽  
Rudolf Schultz
Keyword(s):  
Volcanic Activity ◽  
Main Shock ◽  
Tectonic Setting ◽  
Focal Depth ◽  
Building Codes ◽  
General Area ◽  
Populated Area ◽  
Shallow Subsurface ◽  
San Salvador ◽  
Zoning Regulations

abstract The San Salvador earthquake of May 3, 1965 was preceded by a local seismic swarm of three months duration. The main shock was destructive in a densely populated area of not more than 15 km in radius; the same general area was damaged in the earthquakes of 1576, 1659, 1798, 1839, 1854, 1873, 1880, 1917, and 1919. Over 120 casualties were reported. The epicenter has been located on the south rim of the Median Trough, a post-Pliocene structure which accounts for the high seismic and volcanic activity in the region. The observed intensity is attributable to shallow focal depth and to the presence of thick inhomogeneous beds of fluviatile pumice. The tectonic setting and shallow subsurface factors should be recognized in future building codes and zoning regulations.

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