scholarly journals Seismotectonics of Malatya Fault, Eastern Turkey

2019 ◽  
Vol 11 (1) ◽  
pp. 1098-1111 ◽  
Author(s):  
Diğdem Acarel ◽  
Musavver Didem Cambaz ◽  
Fatih Turhan ◽  
Ahu Kömeç Mutlu ◽  
Remzi Polat
Keyword(s):  
Fault Zone ◽  
Significant Contribution ◽  
Active Fault ◽  
Fault Zones ◽  
North Anatolian Fault Zone ◽  
Active Structure ◽  
Tectonic History ◽  
Major Fault ◽  
Internal Deformation ◽  
Seismic Hazard Estimation

Abstract Turkey is located in a seismically active region with a complex tectonic history. In order to perform seismic risk assessment precisely, major fault zones (North Anatolian Fault Zone and East Anatolian Fault Zone) that are well defined are monitored continuously. It is a widely known fact that intraplate settings, such as Anatolian Plate, in which devastating earthquakes may occur, need to be observed densely. In this study, we investigate the seismotectonics of Malatya Fault within the Malatya Ovacık Fault Zone (MOFZ), which is one of the major agents responsible for internal deformation acting on Anatolian Plate. Recent geological and paleoseismological studies underline the necessity of comprehending the seismicity and latency of a major earthquake in this fault zone.We applied traditional techniques to investigate data of such a region. Earthquakes that occured in the vicinity of Malatya Fault between the years 2011 and mid-2019 are employed in a detailed analysis. The results of this study are constrained by the distribution of sensor networks in the region, yet allowing to define an active structure which is not included in the active fault map of Turkey, therefore, making a significant contribution to seismic hazard estimation.

DETAIL GRAVITY PROFILE ACROSS SAN ANDREAS FAULT ZONE

Geophysics ◽  
1967 ◽  
Vol 32 (2) ◽  
pp. 297-301 ◽  
Author(s):  
S. N. Domenico
Keyword(s):  
Fault Zone ◽  
Mojave Desert ◽  
San Andreas Fault ◽  
Surface Expression ◽  
Fault Zones ◽  
Rock Masses ◽  
San Andreas ◽  
Major Fault ◽  
Reduced Density ◽  
Gravity Profile

A gravity profile was obtained from closely spaced readings along a traverse approximately nine miles in length across the San Andreas fault zone immediately south of Palmdale, California in the western Mojave Desert. Corrected gravity values show a slight but distinctive minimum associated with the fault zone which may be attributed to the reduced density of the shattered rock masses in the fault zone. The existence of this minimum suggests that major fault zones may be traced across terrain, on which surface expression of the fault does not exist, by successive profiles across the suspected position of the fault zone.

scholarly journals CONTEMPORARY GEODYNAMICS OF THE GAROMAI ACTIVE FAULT (SAKHALIN ISLAND)

2019 ◽  
Vol 10 (2) ◽  
pp. 561-567
Author(s):  
N. F. Vasilenko ◽  
A. S. Prytkov
Keyword(s):  
Fault Zone ◽  
Active Fault ◽  
Surface Deformation ◽  
Fault Zones ◽  
Sakhalin Island ◽  
Tectonic Activity ◽  
Relative Deformation ◽  
Survey Period ◽  
Potential Threat ◽  
Deformation Processes

In the northern Sakhalin Island, the tectonic activity of the fault zones is a potential threat to the industrial infrastructure of the petroleum fields. Recently, the background seismicity has increased at the Hokkaido‐Sakhalin fault that consists of several segments, including the Garomai active fault. In the studies of the regional deformation processes, it is important not only to analyze the seismic activity, but also to quantitatively assess the dynamics of deformation accumulation in the fault zones. In order to study the contemporary geodynamics of the Garomai fault, a local GPS/GLONASS network has been established in the area wherein trunk oil and gas pipelines are installed across the fault zone. Based on the annual periodic measurements taken in 2006–2016, we study the features of surface deformation and calculate the rates of displacements caused by the tectonic activity in the fault zone. During the survey period, no significant displacement of the fault wings was revealed. In the immediate vicinity of the fault zone, multidirectional horizontal displacements occur at a rate up to 1.6 mm/yr, and uplifting of the ground surface takes place at a rate of 3.4 mm/yr. This pattern of displacements is a reflection of local deformation processes in the fault zone. At the western wing of the fault, a maximum deformation rate amounts to 1110–6 per year. The fault is a boundary mark of a transition from lower deformation rates at the eastern wing to higher ones at the west wing. In contrast to the general regional compression setting that is typical of the northern Sakhalin Island, extension is currently dominant in the Garomai fault zone. The estimated rates of relative deformation in the vicinity of the Garomai fault give grounds to classify it as ‘hazardous’.

scholarly journals Quantitative determination of the lowest density domain in major fault zones via medical X-ray computed tomography

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Akiyuki Iwamori ◽  
Hideo Takagi ◽  
Nobutaka Asahi ◽  
Tatsuji Sugimori ◽  
Eiji Nakata ◽  
...  
Keyword(s):  
Fault Zone ◽  
Atomic Number ◽  
Density Ratio ◽  
Effective Atomic Number ◽  
Fault Zones ◽  
Ct Number ◽  
Fault Rock ◽  
Major Fault ◽  
X Ray Computed

AbstractDetermination of the youngest active domains in fault zones that are not overlain by Quaternary sedimentary cover is critical for evaluating recent fault activity, determining the current local stress field, and mitigating the impacts of future earthquakes. Considering the exhumation of a fault zone, the youngest active domain in a fault zone is supposed to correspond to the activity at the minimum fault depth of a buried fault, such that the most vulnerable area, which possesses the lowest rock/protolith density ratio, is assumed to be indicative of this recent fault activity. However, it is difficult to measure the density of fault rocks and map the rock/protolith density ratio across a given fault zone. Here, we utilize medical X-ray computed tomography (CT), a non-destructive technique for observing and analyzing materials, to investigate the fault characteristics of several fault zones and their surrounding regions in Japan, and attempt to determine the lowest density domain of a given fault zone based on its CT numbers, which are a function of the density and effective atomic number of the fault rock and protolith. We first investigate the density, void ratio, and effective atomic number of active and inactive fault rocks, and their respective protoliths. We then calculate the CT numbers after reducing the beam-hardening effects on the rock samples and study the relationships among the CT number, density, and effective atomic number. We demonstrate that the density, effective atomic number, and CT number of the fault rock decrease as the youngest active zone, identified by outcrop observation, are approached, such that the region with the lowest CT number and rock/protolith density ratio defines the lowest density domain of a given fault zone. We also discuss the relationship between the lowest density domain and the youngest active domain in major fault zones and investigate the points to be considered when the youngest active domain is identified from the lowest density domain determined by the CT number.

Alpine ultramafic rocks of southwestern British Columbia

1982 ◽  
Vol 19 (6) ◽  
pp. 1156-1173 ◽  
Author(s):  
R. L. Wright ◽  
Joe Nagel ◽  
K. C. McTaggart
Keyword(s):  
British Columbia ◽  
Fault Zone ◽  
Fault Zones ◽  
Ultramafic Rocks ◽  
Fraser River ◽  
Major Fault ◽  
Mechanical Injection

Ultramafic rocks of the Hozameen, Bridge River, and Cache Creek ophiolite assemblages show much variety. The Coquihalla belt of the Hozameen ophiolite assemblage, almost completely serpentinized, is elongate, narrow, and lies along a major fault. Three ultramafic bodies from the Bridge River ophiolite differ markedly from each other. (1) The Pioneer peridotite is a relatively small lens (4 km by 2 km), unaltered, well layered, and fault bounded. (2) The Shulaps body, one of the largest in British Columbia, is bounded on the northeast by a major fault and shows a wide mélange zone on the southwest. (3) A serpentinite body at Lillooet appears to be a steeply dipping slab in the Fraser River fault zone. At Cache Creek, serpentinite bodies are small and appear to be fragments in a mélange. Layers, transgressive sheets, and pods in the Pioneer and Shulaps bodies originated in the mantle, probably by one or several processes: metamorphic differentiation, metasomatism, and mechanical injection. Some ultramafic bodies were emplaced onto the crust by obduction but others, strongly serpentinized, that lie in fault zones may have been squeezed into their present positions.

scholarly journals Active Faulting in Lake Constance (Austria, Germany, Switzerland) Unraveled by Multi-Vintage Reflection Seismic Data

2021 ◽  
Vol 9 ◽  
Author(s):  
S.C. Fabbri ◽  
C. Affentranger ◽  
S. Krastel ◽  
K. Lindhorst ◽  
M. Wessels ◽  
...  
Keyword(s):  
Fault Zone ◽  
Seismic Data ◽  
Single Channel ◽  
Fault Zones ◽  
Lake Constance ◽  
Earthquake Catalog ◽  
Tectonic Structures ◽  
Reflection Seismic ◽  
The North ◽  
Major Fault

Probabilistic seismic hazard assessments are primarily based on instrumentally recorded and historically documented earthquakes. For the northern part of the European Alpine Arc, slow crustal deformation results in low earthquake recurrence rates and brings up the necessity to extend our perspective beyond the existing earthquake catalog. The overdeepened basin of Lake Constance (Austria, Germany, and Switzerland), located within the North-Alpine Molasse Basin, is investigated as an ideal (neo-) tectonic archive. The lake is surrounded by major tectonic structures and constrained via the North Alpine Front in the South, the Jura fold-and-thrust belt in the West, and the Hegau-Lake Constance Graben System in the North. Several fault zones reach Lake Constance such as the St. Gallen Fault Zone, a reactivated basement-rooted normal fault, active during several phases from the Permo-Carboniferous to the Mesozoic. To extend the catalog of potentially active fault zones, we compiled an extensive 445 km of multi-channel reflection seismic data in 2017, complementing a moderate-size GI-airgun survey from 2016. The two datasets reveal the complete overdeepened Quaternary trough and its sedimentary infill and the upper part of the Miocene Molasse bedrock. They additionally complement existing seismic vintages that investigated the mass-transport deposit chronology and Mesozoic fault structures. The compilation of 2D seismic data allowed investigating the seismic stratigraphy of the Quaternary infill and its underlying bedrock of Lake Constance, shaped by multiple glaciations. The 2D seismic sections revealed 154 fault indications in the Obersee Basin and 39 fault indications in the Untersee Basin. Their interpretative linkage results in 23 and five major fault planes, respectively. One of the major fault planes, traceable to Cenozoic bedrock, is associated with a prominent offset of the lake bottom on the multibeam bathymetric map. Across this area, high-resolution single channel data was acquired and a transect of five short cores was retrieved displaying significant sediment thickness changes across the seismically mapped fault trace with a surface-rupture related turbidite, all indicating repeated activity of a likely seismogenic strike-slip fault with a normal faulting component. We interpret this fault as northward continuation of the St. Gallen Fault Zone, previously described onshore on 3D seismic data.

scholarly journals ORACLES ON FAULTS: A PROBABLE LOCATION OF A “LOST” ORACLE OF APOLLO NEAR OROVIAI (NORTHERN EUBOEA ISLAND, GREECE) VIEWED IN ITS GEOLOGICAL AND GEOMORPHOLOGICAL CONTEXT

2017 ◽  
Vol 43 (2) ◽  
pp. 829 ◽  
Author(s):  
I. Mariolakos ◽  
V. Nikolopoulos ◽  
I. Bantekas ◽  
N. Palyvos
Keyword(s):  
Fault Zone ◽  
Active Fault ◽  
Geographical Location ◽  
Archaeological Site ◽  
Hydrothermal Activity ◽  
Fault Zones ◽  
Geological Environment ◽  
Active Fault Zone ◽  
Rocky Slope ◽  
Central Greece

At a newly discovered archaeological site at Aghios Taxiarches in Northern Euboea, two votive inscribed stelae were found in 2001 together with hellenistic pottery next to ancient wall ruins on a steep and high rocky slope. Based on the inscriptions and the geographical location of the site we propose the hypothesis that this is quite probably the spot where the oracle of “Apollo Selinountios” (mentioned by Strabo) would stand in antiquity. The wall ruins of the site are found on a very steep bedrock escarpment of an active fault zone, next to a hanging valley, a high waterfall and a cave. The geomorphological and geological environment of the site is linked directly to the regional geodynamical context of Central Greece, a region of tectonic turmoil throughout the Pleistocene and Holocene, characterised by distinct landscapes produced by the activity of active fault zones, intense seismicity, and in part, volcanism and hydrothermal activity. The geomorphological and geological similarities of the Ag. Taxiarches site with those of the oracle at Delphi, seem to provide further support to the hypothesis that the former site can well be that of an ancient oracle, given the recently established connections between the geological environment at Delphi and Apollo’s oracle there. Definitive verification of our hypothesis can only be obtained by further, detailed archaeological study, whereas geological/geomorphological, geochemical, and geochronological studies would be necessary to clarify the connection that the cave lying next to the wall remains may had with the site’s function.

scholarly journals Early gold-bearing quartz veins within the Rivière-Héva fault zone, Abitibi subprovince, Quebec, Canada

2018 ◽  
Vol 55 (10) ◽  
pp. 1139-1157 ◽  
Author(s):  
Francis Guay ◽  
Pierre Pilote ◽  
Réal Daigneault ◽  
Vicki McNicoll
Keyword(s):  
Fault Zone ◽  
Thrust Fault ◽  
Fault Zones ◽  
Ductile Deformation ◽  
Vein System ◽  
Quartz Veins ◽  
Abitibi Subprovince ◽  
Major Fault ◽  
High Degree ◽  
Gold Bearing

The Malartic Lakeshore showing is a gold-bearing quartz vein system located within the major Rivière-Héva fault zone (RHFZ) of the southern Abitibi greenstone belt. This fault separates the 2702–2700 Ma felsic Héva Formation from the 2708 Ma mafic-ultramafic Dubuisson Formation. A swarm of thin diorite dykes with lamprophyric facies and gold-bearing quartz veins are present only on the Dubuisson side of the fault. The 30–70 cm thick gold quartz veins are boudinaged and folded. Veins are banded and associated with pyrite, chalcopyrite, galena, barite, and gold. The study area is characterized by a high degree of ductile deformation associated with the RHFZ and manifested by the southeast-trending “principal schistosity” (Sp). Stretching lineations plunge moderately to shallowly toward the southeast as a result of shortening followed by late directional shearing during a transpressive deformation. A sample from the Héva Formation yielded a zircon U–Pb age of 2698.2 ± 0.8 Ma, and a diorite dyke produced an age of 2694.3 ± 2.5 Ma. Quartz veins are crosscut by dykes, and both are affected by the Sp fabric, indicating an early emplacement with respect to the deformation. This situation contrasts with the orogenic gold veins found in association with major fault zones. A near-synvolcanic magmatic hydrothermal origin is proposed for this gold vein system. Because all subvertical units in the area are south facing, the presence of the older Dubuisson Formation over the younger Héva Formation is attributed to the RHFZ acting as a significant reverse or thrust fault.

Three Ozark earthquakes*

1949 ◽  
Vol 39 (1) ◽  
pp. 1-8
Author(s):  
Ross R. Heinrich
Keyword(s):  
Fault Zone ◽  
Fault Zones ◽  
The Other ◽  
Fault System ◽  
Macroseismic Data ◽  
Mississippi Embayment ◽  
Major Fault ◽  
Minor Activity

Abstract This paper continues the discussion of the seismicity of the Middle Mississippi Basin. Seismographic and macroseismic data are presented on three Missouri earthquakes: (1) the Little Saline Creek earthquake, January 15, 1945; (2) the Doniphan, Missouri, earthquake, May 15, 1946; and (3) the Little Black River earthquake, December 1, 1947. Many geological studies have established the existence of three major fault zones in the basement; the Mississippi embayment zone, the Shawneetown-Rough Creek zone, and the Ste. Genevieve zone. The earthquake of January 15, 1945, is additional evidence that the Ste. Genevieve fault zone is seismically active. The other two shocks are not directly associated with the major fault zones. They, together with previous similar minor activity, may be associated with a deep-seated fault system near the physiographic margin of the Ozarks or with deep-seated fractures on the southeastern flank of the uplift.

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