Three Ozark earthquakes*

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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DETAIL GRAVITY PROFILE ACROSS SAN ANDREAS FAULT ZONE

Geophysics ◽

10.1190/1.1439868 ◽

1967 ◽

Vol 32 (2) ◽

pp. 297-301 ◽

Cited By ~ 2

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.

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Recent and active deformation in the North Evia domain, a diffuse plate boundary between Eurasia and Aegean plates in the Western termination of the North Anatolian Fault.

10.5194/egusphere-egu21-12153 ◽

2021 ◽

Author(s):

Fabien Caroir ◽

Frank Chanier ◽

Virginie Gaullier ◽

Julien Bailleul ◽

Agnès Maillard-Lenoir ◽

...

Keyword(s):

Fault Zone ◽

Plate Boundary ◽

Fault Zones ◽

North Anatolian Fault ◽

Fault System ◽

Eurasian Plate ◽

Slip Rates ◽

The North ◽

South West ◽

North Aegean

The Anatolia-Aegean microplate is currently extruding toward the South and the South-West. This extrusion is classically attributed to the southward retreat of the Aegean subduction zone together with the northward displacement of the Arabian plate. The displacement of Aegean-Anatolian block relative to Eurasia is accommodated by dextral motion along the North Anatolian Fault (NAF), with current slip rates of about 20 mm/yr. The NAF is propagating westward within the North Aegean domain where it gets separated into two main branches, one of them bordering the North Aegean Trough (NAT). This particular context is responsible for dextral and normal stress regimes between the Aegean plate and the Eurasian plate. South-West of the NAT, there is no identified major faults in the continuity of the NAF major branch and the plate boundary deformation is apparently distributed within a wide domain. This area is characterised by slip rates of 20 to 25 mm/yr relative to Eurasian plate but also by clockwise rotation of about 10&#176; since ca 4 Myr. It constitutes a major extensional area involving three large rift basins: the Corinth Gulf, the Almiros Basin and the Sperchios-North Evia Gulf. The latter develops in the axis of the western termination of the NAT, and is therefore a key area to understand the present-day dynamics and the evolution of deformation within this diffuse plate boundary area.Our study is mainly based on new structural data from field analysis and from very high resolution seismic reflexion profiles (Sparker 50-300 Joules) acquired during the WATER survey in July-August 2017 onboard the R/V &#8220;T&#233;thys II&#8221;, but also on existing data on recent to active tectonics (i.e. earthquakes distribution, focal mechanisms, GPS data, etc.). The results from our new marine data emphasize the structural organisation and the evolution of the deformation within the North Evia region, SW of the NAT.The combination of our structural analysis (offshore and onshore data) with available data on active/recent deformation led us to define several structural domains within the North Evia region, at the western termination of the North Anatolian Fault. The North Evia Gulf shows four main fault zones, among them the Central Basin Fault Zone (CBFZ) which is obliquely cross-cutting the rift basin and represents the continuity of the onshore Kamena Vourla - Arkitsa Fault System (KVAFS). Other major fault zones, such as the Aedipsos Politika Fault System (APFS) and the Melouna Fault Zone (MFZ) played an important role in the rift initiation but evolved recently with a left-lateral strike-slip motion. Moreover, our seismic dataset allowed to identify several faults in the Skopelos Basin including a large NW-dipping fault which affects the bathymetry and shows an important total vertical offset (>300m). Finally, we propose an update of the deformation pattern in the North Evia region including two lineaments with dextral motion that extend southwestward the North Anatolian Fault system into the Oreoi Channel and the Skopelos Basin. Moreover, the North Evia Gulf domain is dominated by active N-S extension and sinistral reactivation of former large normal faults.

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Low-temperature thermochronology of fault zones

10.5194/egusphere-egu2020-6060 ◽

2020 ◽

Author(s):

Takahiro Tagami

Keyword(s):

Low Temperature ◽

Fault Zone ◽

Fission Track ◽

Thermal Sensitivity ◽

Fault Zones ◽

Fault System ◽

Vein Formation ◽

Fission Track Thermochronology ◽

Mineral Vein ◽

Host Rocks

Thermal signatures as well as timing of fault motions can be constrained by thermochronological analyses of fault-zone rocks (e.g., Tagami, 2012, 2019).&#160; Fault-zone materials suitable for such analyses are produced by tectocic and geochemical processes, such as (1) mechanical fragmentation of host rocks, grain-size reduction of fragments and recrystallization of grains to form mica and clay minerals, (2) secondary heating/melting of host rocks by frictional fault motions, and (3) mineral vein formation as a consequence of fluid advection associated with fault motions.&#160; The geothermal structure of fault zones are primarily controlled by the following three factors: (a) regional geothermal structure around the fault zone that reflect background thermo-tectonic history of studied province, (b) frictional heating of wall rocks by fault motions and resultant heat transfer into surrounding rocks, and (c) thermal influences by hot fluid advection in and around the fault zone.&#160; Geochronological/thermochronological methods widely applied in fault zones are K-Ar (40Ar/39Ar), fission-track (FT), and U-Th methods.&#160; In addition, (U-Th)/He, OSL, TL and ESR methods are applied in some fault zones, in order to extract temporal information related to low temperature and/or recent fault activities.&#160; Here I briefly review the thermal sensitivity of individual thermochronological systems, which basically controls the response of each method against faulting processes.&#160; Then, the thermal sensitivity of FTs is highlighted, with a particular focus on the thermal processes characteristic to fault zones, i.e., flash and hydrothermal heating.&#160; On these basis, representative examples as well as key issues, including sampling strategy, are presented to make thermochronological analysis of fault-zone materials, such as fault gouges, pseudotachylytes and mylonites, along with geological, geomorphological and seismological implications.&#160; Finally, the thermochronological analyses of the Nojima fault are overviewed, as an example of multidisciplinary investigations of an active seismogenic fault system.&#160;References:<ol><li>Tagami, 2012. Thermochronological investigation of fault zones. Tectonophys., 538-540, 67-85, doi:10.1016/j.tecto.2012.01.032.</li> <li>Tagami, 2019. Application of fission track thermochronology to analyze fault zone activity. Eds. M. G. Malusa, P. G. Fitzgerald, Fission track thermochronology and its application to geology, 393pp, 221-233, doi: 10.1007/978-3-319-89421-8_12.</li> </ol>

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

Progress in Earth and Planetary Science ◽

10.1186/s40645-021-00442-7 ◽

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.

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Faults and magma reservoirs along the Southern Andes Volcanic zone (SAVZ): linking oservations and numerical models of stress change controlling magmatic and hydrothermal fluid flow

10.5194/egusphere-egu2020-11473 ◽

2020 ◽

Author(s):

Javiera Ruz ◽

Muriel Gerbault ◽

José Cembrano ◽

Pablo Iturrieta ◽

Camila Novoa Lizama ◽

...

Keyword(s):

Fluid Flow ◽

Stress Field ◽

Fault Zone ◽

Numerical Models ◽

Fluid Pressure ◽

Seismic Inversion ◽

Fault Zones ◽

Fault System ◽

Far Field ◽

Trigger Failure

The Chilean margin is amongst the most active seismic and volcanic areas on Earth. It hosts active and fossil geothermal and mineralized systems of economic interest documenting significant geofluid migration through the crust. By comparing numerical models with field and geophysical data,&#160;we aim at pinning when and where fluid migration occurs through porous domains, fault zone conduits, or remains stored at depth awaiting a more appropriate stress field. Dyking and volcanic activity occur within fault zones along the SAVZ, linked with stress field variations in spatial and temporal association with &#8211;short therm- seismicity and -long term- oblique plate convergence. Volcanoes and geothermal domains are mostly located along or at the intersection of margin-oblique fault zones (Andean Transverse Faults), and along margin-parallel strike slip zones, some which may cut the entire lithosphere (Liqui&#241;e-Ofqui fault system). Whereas the big picture displays fluid flow straight to the surface, at close look significant offsets between crustal structures occur. 3D numerical models using conventional elasto-plastic rheology provide insights on the interaction of (i) an inflating magmatic cavity, (ii) a slipping fault zone, and (iii)&#160;regional tectonic stresses. Applying either (i) a magmatic overpressure or (ii) a given fault slip can trigger failure of the intervening rock, and generate either i) fault motion or ii) magmatic reservoir failure, respectively, but only for distances less than the structures' breadth even at low rock strength. However, at greater inter-distances the bedrock domain in between the fault zone and the magmatic cavity undergoes dilatational strain of the order of 1-5x10-5. This dilation opens the bedrock&#8217;s pore space and forms &#171;pocket domains&#187; that may store up-flowing over-pressurized fluids, which may then further chemically interact with the bedrock, for the length of time that these pockets remain open. These porous pockets can reach kilometric size,&#160;questioning their parental link with outcropping plutons along the margin. Moreover, bedrock permeability may also increase as fluid flow diminishes effective bedrock friction and cohesion. Comparison with rock experiments indicates that such stress and fluid pressure changes may eventually trigger failure at the intermediate timescale (repeated slip or repeated inflation). Finally, incorporating far field compression (iii) loads the bedrock to a state of stress at the verge of failure. Then, failure around the magmatic reservoir or at the fault zone occurs for lower loading. Permanent tectonic loading on the one hand, far field episodic seismic inversion of the stress field on the other, and localized failure all together promote a transient stress field, thus explaining the occurrence of transient fluid pathways on seemingly independent timescales. These synthetic models are then discussed with regards to specific cases along the SVZ, particularly the Tatara-San Pedro area (~36&#176;S), where magnetotelluric profiles document conductive volumes at different depths underneath active faults, volcanic edifices and geothermal vents. We discuss the mechanical link between these deep sources and surface structures.

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Alpine ultramafic rocks of southwestern British Columbia

Canadian Journal of Earth Sciences ◽

10.1139/e82-099 ◽

1982 ◽

Vol 19 (6) ◽

pp. 1156-1173 ◽

Cited By ~ 4

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.

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The role of oroclinal bending in the structural evolution of the Central Anatolian Plateau: evidence of a regional changeover from shortening to extension

Geologica Carpathica ◽

10.2478/v10096-011-0026-7 ◽

2011 ◽

Vol 62 (4) ◽

pp. 345-359 ◽

Cited By ~ 13

Author(s):

Erman Özsayin ◽

Kadir Dirik

Keyword(s):

Fault Zone ◽

Structural Evolution ◽

Shear Zones ◽

Fault Zones ◽

Fault System ◽

Western Boundary ◽

Southeastern Part ◽

Anatolian Plateau ◽

Isparta Angle

The role of oroclinal bending in the structural evolution of the Central Anatolian Plateau: evidence of a regional changeover from shortening to extensionThe NW-SE striking extensional Inönü-Eskişehir Fault System is one of the most important active shear zones in Central Anatolia. This shear zone is comprised of semi-independent fault segments that constitute an integral array of crustal-scale faults that transverse the interior of the Anatolian plateau region. The WNW striking Eskişehir Fault Zone constitutes the western to central part of the system. Toward the southeast, this system splays into three fault zones. The NW striking Ilıca Fault Zone defines the northern branch of this splay. The middle and southern branches are the Yeniceoba and Cihanbeyli Fault Zones, which also constitute the western boundary of the tectonically active extensional Tuzgölü Basin. The Sultanhanı Fault Zone is the southeastern part of the system and also controls the southewestern margin of the Tuzgölü Basin. Structural observations and kinematic analysis of mesoscale faults in the Yeniceoba and Cihanbeyli Fault Zones clearly indicate a two-stage deformation history and kinematic changeover from contraction to extension. N-S compression was responsible for the development of the dextral Yeniceoba Fault Zone. Activity along this structure was superseded by normal faulting driven by NNE-SSW oriented tension that was accompanied by the reactivation of the Yeniceoba Fault Zone and the formation of the Cihanbeyli Fault Zone. The branching of the Inönü-Eskişehir Fault System into three fault zones (aligned with the apex of the Isparta Angle) and the formation of graben and halfgraben in the southeastern part of this system suggest ongoing asymmetric extension in the Anatolian Plateau. This extension is compatible with a clockwise rotation of the area, which may be associated with the eastern sector of the Isparta Angle, an oroclinal structure in the western central part of the plateau. As the initiation of extension in the central to southeastern part of the Inönü-Eskişehir Fault System has similarities with structures associated with the Isparta Angle, there may be a possible relationship between the active deformation and bending of the orocline and adjacent areas.

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

Frontiers in Earth Science ◽

10.3389/feart.2021.670532 ◽

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.

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

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2018-0029 ◽

2018 ◽

Vol 55 (10) ◽

pp. 1139-1157 ◽

Cited By ~ 1

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.

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Fluid Inclusions Record Hydrocarbon Charge History in the Shunbei Area, Tarim Basin, NW China

Geofluids ◽

10.1155/2020/8847247 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Ziye Lu ◽

Yingtao Li ◽

Ning Ye ◽

Shaonan Zhang ◽

Chaojin Lu ◽

...

Keyword(s):

Fault Zone ◽

Fluid Inclusions ◽

Tarim Basin ◽

Homogenization Temperature ◽

Fault Zones ◽

Carbonate Reservoirs ◽

Fault System ◽

Middle Ordovician ◽

History Of ◽

Hydrocarbon Charge

The exploration of deeply buried hydrocarbon is still a challenge for the petroleum geology. The Shunbei area is a newly discovered oil fields, located in the center of the Tarim Basin. The oil is mainly yielded from the Middle–Lower Ordovician carbonate reservoirs with depth > 7000 m in the Shunbei No. 1 and No. 5 fault zones. Calcite cements filled in vugs (v-calcite) and fractures (f-calcite) are identified in limestones and dolostones of the carbonate reservoirs. F-calcites in the Shunbei No. 1 fault zone trap secondary inclusions in trails, which comprise liquid-dominated biphase aqueous inclusions, liquid-dominated biphase oil inclusions, and/or oil-bearing triphase inclusions. F-calcite and v-calcite in the No. 5 fault zone trap secondary inclusions in trails, which consist of liquid-only monophase aqueous inclusions, liquid-dominated biphase aqueous inclusions, liquid-dominated biphase oil inclusions, liquid-only monophase oil inclusions, and/or oil-bearing triphase inclusions. The ranges of the homogenization temperature ( T h ) and ice-melting temperature ( T m − ice ) in the Shunbei No. 1 fault zone are, respectively, 130–150°C and -2.1–-1.5°C. The coexistence of liquid-only and liquid-dominated aqueous inclusions in the Shunbei No. 5 fault zone indicates that the aqueous inclusions are trapped at low temperatures. The aqueous inclusions in the Shunbei No. 5 fault zone show a range from -0.4 to -0.2°C in T m − ice which is very close to the meteoric fluid. In the context of the burial-thermal history and the Cambrian source rock evolution, the charging process of hydrocarbon in the Shunbei No. 1 and No. 5 fault zones corresponds to the Silurian and Middle Ordovician, respectively. Results of fluid inclusions indicate a tightly coupling relationship between the hydrocarbon charging process and fault system evolution in the Shunbei area. This study reveals the application of fluid inclusion under the systemically petrographic constraints to decipher the charging history of hydrocarbon, especially for the deeply buried reservoirs.

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