scholarly journals Interdisciplinary Fracture Network Characterization in the Crystalline Basement: A case study from the Southern Odenwald, SW Germany

2021 ◽  
Author(s):  
Matthis Frey ◽  
Claire Bossennec ◽  
Lukas Seib ◽  
Kristian Bär ◽  
Ingo Sass
Keyword(s):  
Power Plants ◽  
Active Faults ◽  
Gravity Anomalies ◽  
Fracture Network ◽  
Fault Zones ◽  
Crystalline Basement ◽  
Upper Rhine Graben ◽  
Reservoir Conditions ◽  
Lineament Analysis ◽  
Deep Boreholes

Abstract. The crystalline basement is considered a ubiquitous and almost inexhaustible source of geothermal energy in the Upper Rhine Graben and other regions worldwide. The hydraulic properties of the basement, which are one of the key factors for the productivity of geothermal power plants, are primarily controlled by hydraulically active faults and fractures. While the most accurate in situ information about the general fracture network is obtained from image logs of deep boreholes, such data are generally sparse, costly and thus often not openly accessible. To circumvent this problem, an outcrop analogue study with interdisciplinary geoscientific methods was conducted in the Tromm Granite, located in the southern Odenwald at the northeastern margin of the URG. Using LiDAR scanning, the key characteristics of the fracture network were extracted in a total of five outcrops, additionally complemented by lineament analysis of two different digital elevation models. Based on this, discrete fracture network (DFN) models were developed to calculate equivalent permeability tensors under assumed reservoir conditions. The influence of different parameters, such as fracture orientation, density, aperture and mineralization was investigated. In addition, extensive gravity and radon measurements were carried out in the study area, allowing for more precise localization of fault zones with naturally increased porosity and permeability. Gravity anomalies served as input data for a stochastic density inversion, through which areas of increased open porosity were identified. A laterally heterogeneous fracture network characterizes the Tromm Granite, with the highest natural permeabilities expected at the pluton margin, due to the influence of large shear and fault zones.

3-Dimensional Inversion for Gravity Anomaly Calculation in Complex Geologic Region

2014 ◽  
Vol 962-965 ◽  
pp. 238-241 ◽  
Author(s):  
Gui Ju Wu ◽  
Hui Liu ◽  
Zheng Bo Zou ◽  
Guang Liang Yang ◽  
Chong Yang Shen
Keyword(s):  
Gravity Anomaly ◽  
Gravity Data ◽  
Active Faults ◽  
Physical Property ◽  
Gravity Anomalies ◽  
Research Area ◽  
Fault Zones ◽  
Longmenshan Fault Zone ◽  
3 Dimensional ◽  
Longmenshan Fault

In the gravity anomaly dectection and the inversion of physical property, the parameters can reflect the characters and details of source. At the same time, it can enhance the resolution of the source. In this paper, gravity data from global 1-minute grids are applied to inverse the structure of Longmenshan fault zone, other small faluts, several active faults and geological stratum, the research area where is complex geologic region. The main goal of this paper is an attempt to interpret the gravity anomalies of faults in the Longmenshan Fault zones.

CRUSTAL DEFORMATION STUDIES IN JAVA (INDONESIA) USING GPS

2009 ◽  
Vol 03 (02) ◽  
pp. 77-88 ◽  
Author(s):  
HASANUDDIN Z. ABIDIN ◽  
HERI ANDREAS ◽  
TERUYUKI KATO ◽  
TAKEO ITO ◽  
IRWAN MEILANO ◽  
...  
Keyword(s):  
Active Faults ◽  
Fault Zones ◽  
First Year ◽  
Horizontal Deformation ◽  
West Java ◽  
Plate Movement ◽  
Tsunami Earthquake ◽  
Second Year ◽  
Seismic Deformation ◽  
Large Earthquakes

Along the Java trench the Australian–Oceanic plate is moving and pushing onto and subducting beneath the Java continental crust at a relative motion of about 70 mm/yr in NNE direction. This subduction-zone process imposed tectonic stresses on the fore-arc region offshore and on the land of Java, thus causing the formation of earthquake fault zones to accommodate the plate movement. Historically, several large earthquakes happened in Java, including West Java. This research use GPS surveys method to study the inter-seismic deformation of three active faults in West Java region (i.e. Cimandiri, Lembang and Baribis faults), and the co-seismic and post-seismic deformation related to the May 2006 Yogyakarta and the July 2006 South Java earthquakes. Based on GPS surveys results it was found that the area around Cimandiri, Lembang and Baribis fault zones have the horizontal displacements of about 1 to 2 cm/yr or less. Further research is however still needed to extract the real inter-seismic deformation of the faults from those GPS-derived displacements. GPS surveys have also estimated that the May 2006 Yogyakarta earthquake was caused by the sinistral movement of the (Opak) fault with horizontal co-seismic deformation that generally was less than 10 cm. The post-seismic horizontal deformation of the July 2006 South Java tsunami earthquake has also been estimated using GPS surveys data. In the first year after the earthquake (2006 to 2007), the post-seismic deformation is generally less than 5 cm; and it becomes generally less than 3 cm in the second year (2007 to 2008).

The 2019 Ms 4.2 and 5.2 Beiliu Earthquake Sequence in South China: Complex Conjugate Strike-Slip Faulting Revealed by Rupture Directivity Analysis

2021 ◽  
Author(s):  
Xiaohui He ◽  
Hao Liang ◽  
Peizhen Zhang ◽  
Yue Wang
Keyword(s):  
South China ◽  
Source Parameters ◽  
Active Faults ◽  
Fault Zones ◽  
Strike Slip ◽  
P Wave ◽  
Complex Conjugate ◽  
South China Block ◽  
Rupture Directivity ◽  
Time Duration

Abstract The South China block has been one of the most seismically quiescent regions in China, and the geometries and activities of the Quaternary faults have remained less studied due to the limited outcrops. Thus, source parameters of small-to-moderate earthquakes are important to help reveal the location, geometry distribution, and mechanical properties of the subsurface faults and thus improve the seismic risk assessment. On 12 October 2019, two earthquakes (the Ms 4.2 foreshock and the Ms 5.2 mainshock) occurred within 2 s and are located in southern South China block, near the junction region of the large-scale northeast-trending fault zones and the less continuous northwest-trending fault zones. We determined the point-source parameters of the two events via P-wave polarity analysis and regional waveform modeling, and the resolved focal mechanisms are significantly different with the minimum 3D rotation angle of 52°. We then resolved the rupture directivity of the two events by analyzing the azimuth variation of the source time duration and found the Ms 4.2 foreshock ruptured toward north-northwest for ∼1.0 km, and the Ms 5.2 mainshock ruptured toward east-southeast (ESE) for ∼1.5 km, implying conjugate strike-slip faulting. The conjugate causative faults have not been mapped on the regional geological map, and we infer that the two faults may be associated with the northwest-trending Bama-Bobai fault zone (the Shiwo section). These active faults are optimally oriented in the present-day stress field (northwest-southeast) and thus may now be potentially accumulating elastic strain to be released in a future large earthquake.

scholarly journals Application of the Environmental Seismic Intensity scale (ESI 2007) and the European Macroseismic Scale (EMS-98) to the Kalamata (SW Peloponnese, Greece) earthquake (Ms=6.2, September 13, 1986) and correlation with neotectonic structures and active faults

2014 ◽  
Vol 56 (6) ◽  
Author(s):  
Ioannis G. Fountoulis ◽  
Spyridon D. Mavroulis
Keyword(s):  
Structural Damage ◽  
Active Fault ◽  
Main Shock ◽  
Active Faults ◽  
Seismic Hazard Assessment ◽  
Seismic Intensity ◽  
Fault Zones ◽  
Earthquake Sequence ◽  
Ground Subsidence ◽  
Earthquake Scenario

On September 13, 1986, a shallow earthquake (Ms=6.2) struck the city of Kalamata and the surrounding areas (SW Peloponnese, Greece) resulting in 20 fatalities, over 300 injuries, extensive structural damage and many earthquake environmental effects (EEE). The main shock was followed by several aftershocks, the strongest of which occurred two days later (Ms=5.4). The EEE induced by the 1986 Kalamata earthquake sequence include ground subsidence, seismic faults, seismic fractures, rockfalls and hydrological anomalies. The maximum ESI 2007 intensity for the main shock has been evaluated as IX<sub>ESI 2007</sub>, strongly related to the active fault zones and the reactivated faults observed in the area as well as to the intense morphology of the activated Dimiova-Perivolakia graben, which is a 2nd order neotectonic structure located in the SE margin of the Kalamata-Kyparissia mega-graben and bounded by active fault zones. The major structural damage of the main shock was selective and limited to villages founded on the activated Dimiova-Perivolakia graben (IX<sub>EMS-98</sub>) and to the Kalamata city (IX<sub>EMS-98</sub>) and its eastern suburbs (IX<sub>EMS-98</sub>) located at the crossing of the prolongation of two major active fault zones of the affected area. On the contrary, damage of this size was not observed in the surrounding neotectonic structures, which were not activated during this earthquake sequence. It is concluded that both intensity scales fit in with the neotectonic regime of the area. The ESI 2007 scale complemented the EMS-98 seismic intensities and provided a completed picture of the strength and the effects of the September 13, 1986, Kalamata earthquake on the natural and the manmade environment. Moreover, it contributed to a better picture of the earthquake scenario and represents a useful and reliable tool for seismic hazard assessment.

scholarly journals Structural model of the Northern Latium volcanic area constrained by MT, gravity and aeromagnetic data

1997 ◽  
Vol 40 (5) ◽  
Author(s):  
P. Capuano ◽  
G. Florio ◽  
P. Gasparini
Keyword(s):  
Structural Model ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Volcanic Area ◽  
Aeromagnetic Data ◽  
Geothermal Exploration ◽  
Magnetotelluric Soundings ◽  
Aeromagnetic Anomalies ◽  
Deep Boreholes

The results of about 120 magnetotelluric soundings carried out in the Vulsini, Vico and Sabatini volcanic areas were modeled along with Bouguer and aeromagnetic anomalies to reconstruct a model of the structure of the shallow (less than 5 km of depth) crust. The interpretations were constrained by the information gathered from the deep boreholes drilled for geothermal exploration. MT and aeromagnetic anomalies allow the depth to the top of the sedimentary basement and the thickness of the volcanic layer to be inferred. Gravity anomalies are strongly affected by the variations of morphology of the top of the sedimentary basement, consisting of a Tertiary flysch, and of the interface with the underlying Mesozoic carbonates. Gravity data have also been used to extrapolate the thickness of the neogenic unit indicated by some boreholes. There is no evidence for other important density and susceptibility heterogeneities and deeper sources of magnetic and/or gravity anomalies in all the surveyed area.

scholarly journals Characterization of Modern and Historical Seismic–Tsunamic Events, and Their Global–Societal Impacts

2021 ◽  
pp. SP501-2021-17
Author(s):  
Yildirim Dilek ◽  
Yujiro Ogawa ◽  
Yasukini Okubo
Keyword(s):  
Disaster Management ◽  
Plate Tectonics ◽  
Power Plants ◽  
Active Faults ◽  
Building Design ◽  
Developed Countries ◽  
High Impact ◽  
Global Banking ◽  
Management Plans ◽  
The Impact

AbstractEarthquakes and tsunamis are high–impact geohazard events that could be extremely destructive when they occur at large magnitudes and intensities, respectively, although their causes and potential locations are, for the most part, predictable within the framework of plate tectonics. Amongst the main reasons for their high impact include enormous numbers of casualties, extensive property damage in vast areas, and significant social and economic disruptions in urban settings where populous residential areas, global banking centres, industrial factories, and critical facilities (nuclear power plants, dams) may be located. In order to reduce the impact of these geohazards, the nations, societies, professional organizations and governments need to collaborate to prepare more effective seismic and tsunami risk assessments, disaster management plans, educational and training programmes for increased preparedness of the public, and strategic plans and objectives for capacity building, skill and knowledge transfer, and building of societal resilience. Improved building design and construction codes, and emergency preparedness and evacuation plans should be part of disaster management plans in countries where destructive earthquakes and tsunamis occurred earlier. Fast increasing population in coastal corridors in developing and developed countries is likely to escalate the social and economic impacts of these geohazards exponentially in the future. The chapters in this book present case studies of some of the most salient earthquake and tsunami events in historical and modern times, their origins and manifestations, and efforts and most effective practices of risk assessment and disaster management implemented by various governments, international organizations and inter–governmental agencies following these events. New methods of computing probabilistic seismic hazard risks, delineating respect distance and damage zones along–across seismically active faults and recognizing tsunamigenic and submarine landslides on the seafloor are introduced. The conclusions presented in the chapters show that: (1) scientific understanding of the characteristics of seismically active faults is paramount; (2) increased local (community), national and global resilience is necessary to empower societal preparedness for earthquake and tsunami events; and, (3) all stakeholders, including policy–makers, scientists, local, state and national governments, media, and world organizations (UNESCO, IUGS, GeoHazards International–GHI, Global Geodetic Observing System–GGOS; National Earthquake Hazards Reduction Program–NEHRP) must work together to disseminate accurate and timely information on geohazards, to develop effective legislation for risk reduction, and to prepare realistic and practical hazard mitigation and management measures.

On the multiscale quantification of fracture network geometry from lineament maps of crystalline basement units

2021 ◽  
Author(s):  
Alberto Ceccato ◽  
Giulia Tartaglia ◽  
Giulio Viola ◽  
Marco Antonellini
Keyword(s):  
Statistical Analysis ◽  
Scaling Laws ◽  
Numerical Models ◽  
Regional Scale ◽  
Fracture Network ◽  
Crystalline Basement ◽  
Fracture Networks ◽  
Spatial Organisation ◽  
Robust Analysis ◽  
Network Properties

&lt;p&gt;Fractured crystalline basement units are attracting increasing attention as potential unconventional reservoirs for natural (oil, heat and water) resources and as potential waste (nuclear, CO&lt;sub&gt;2&lt;/sub&gt;) disposal sites. The focus of the current efforts is the characterisation of the structural permeability of fractured crystalline basement units, which is primarily related to the geology, geometry, and spatial characteristics of fracture networks. Fracture network properties may be scale&amp;#8211;dependent or independent. Thus, a multi&amp;#8211;scale characterisation of fracture networks is usually recommended to quantify the scale&amp;#8211;variability of properties and, eventually, the related predictive scaling laws. Fracture lineament maps are schematic representations of fracture distributions obtained from either manual or automated interpretation of 2D digital models of the earth surface at different scales. From the quantitative analysis on fracture lineament maps, we can retrieve invaluable information on the scale&amp;#8211;dependence of fracture network properties.&lt;/p&gt;&lt;p&gt;Here we present the results of the quantification of fracture network and fracture set properties (orientation, length, spacing, spatial organisation) from multi&amp;#8211; (outcrop to regional) scale 2D lineament maps of two crystalline basement study areas of Western Norway (B&amp;#248;mlo island and Kr&amp;#229;kenes). Lineament maps were obtained from the manual interpretation of orthophotos and 2D digital terrain models retrieved from UAV&amp;#8211;drone and LiDAR surveys.&lt;/p&gt;&lt;p&gt;Analyses aimed at the quantification of: (i) scaling laws for fracture length cumulative distributions, defined through a statistically&amp;#8211;robust fitting method (Maximum Likelihood Estimations coupled with Kolmogorov&amp;#8211;Smirnov tests); (ii) variability of orientation sets as a function of scale; (iii) spatial organisation of fracture sets among scales; (iv) fractal characteristics of fracture networks (fractal exponent). Results suggest that: (i) a statistical analysis considering variable censoring and truncation effects allows to confidently define the best&amp;#8211;fitting scaling laws; (ii) the analysis of orientation variability of fracture sets among different scales may provide important constraints about the geometrical complexity of fracture and fault zones; (iii) the statistical analysis of 2D spacing variability and fracture intensity can be adopted to quantify fracture spatial organisation at different scales.&lt;/p&gt;&lt;p&gt;A statistically robust analysis of the scaling laws, length distributions, spacing, and spatial organisation of lineaments on 2D maps provides reliable results also where only partial or incomplete dataset/lineament maps are available. Such properties are the fundamental input parameters for conceptual (geologic) and numerical (discrete fracture network, DFN) models of fractured crystalline basement reservoirs. Therefore, a statistically robust analysis of fracture lineament maps may help to improve the accuracy of conceptual and numerical models.&lt;/p&gt;

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