Identification Of Active Faults Research Articles

Identification of Active Faults in Lahat and Empat Lawang Region, South Sumatra Province, Based on Seismicity and Focal Mechanism Analysis

The BMKG earthquake catalog data for the 2014-2022 period shows seismic activity in the Gumai Mountains, South Sumatra, which is located southeast of the Ketaun Segment, east of the Musi Segment, and north of the Manna Segment. Seismic activity in this area is important to study as an early indication of the presence of other active fault segments that have not been identified before. Re-analysis on the P and S wave phases picking was carried out for the 26 earthquakes in the period of 2014 to 2022 to ensure the quality of the data used in the processing. The double-difference method was then used to relocate the hypocenter of the earthquake based on a local velocity model to identify an active fault segment lineation in the area. In addition, waveform inversion method was used to obtain the focal mechanism for 7 earthquakes which were successfully analyzed to identify the fault plane direction. By combining the results of seismicity and focal mechanism analysis, we concluded that there are 3 fault segments that have not been identified before. These segments are thought to be strongly responsible for seismic activity in Gumai Mountains in Lahat and Empat Lawang Regencies, South Sumatra, which we determine to be part of the Great Sumatran Fault network.

Identification of active faults and tectonic features through heat flow distribution in the Nankai Trough, Japan, based on high-resolution velocity-estimated bottom-simulating reflector depths

Estimates of heat flow can contribute to our understanding of geological structures in plate convergent zones that produce great earthquakes. We applied automated velocity analysis to obtain the accurate seismic profiles needed for precise heat flow estimates using six new seismic profiles acquired during R/V Kaimei KM18-10 voyage in 2018. We calculated heat flow values in the accretionary wedge of the Nankai Trough off the Kii Peninsula, Japan, from the positions of widespread bottom-simulating reflectors (BSRs) in seismic reflection profiles. Calculated conductive heat flow values from the depth of the BSR agree with previous studies where a regional trend is observed from ~ 50 mW/m2 to < 40 mW/m2 60 km landward from the deformation front. This trend is caused by thickening of accretionary sediments and the subduction of the Philippines Sea plate. Segments of profiles are marked by anomalous high heat flow values. Such anomalies represent alterations of the shallow crustal thermal structure caused either by a combination of topographic affects, surface erosion of the seafloor, or by fluid flow that transports heat by advection. We interpret heat flow anomalies (~ 100 mW/m2) as indicators of active faulting, which correspond to low seismic velocity zones along faults. Our results also showed relatively high heat flow at the landward end of several survey lines close to the Kii Peninsula, which we interpret to the possible presence of plutonic rocks that underlie the Kii Peninsula and extend offshore and may be the cause of geothermal springs, steep geothermal gradients, and high heat flow.Graphical abstract

The Malawi Active Fault Database: An Onshore‐Offshore Database for Regional Assessment of Seismic Hazard and Tectonic Evolution

AbstractWe present the Malawi Active Fault Database (MAFD), an open‐access (https://doi.org/10.5281/zenodo.5507190) geospatial database of 113 fault traces in Malawi and neighboring Tanzania and Mozambique. Malawi is located within the East African Rift's (EAR) Western Branch where active fault identification is challenging because chronostratigraphic data are rare, and/or faults are buried and so do not have a surface expression. The MAFD therefore includes any fault that has evidence for displacement during Cenozoic East African rifting or is buried beneath the rift valley and is favorably oriented to the regional stresses. To identify such faults, we consider a multidisciplinary data set: high‐resolution digital elevation models, previous geological mapping, field observations, seismic reflection surveys from offshore Lake Malawi, and aeromagnetic and gravity data. The MAFD includes faults throughout Malawi, where seismic risk is increasing because of population growth and its seismically vulnerable building stock. We also investigate the database as a sample of the normal fault population in an incipient continental rift. We cannot reject the null hypothesis that the distribution of fault lengths in the MAFD is described by a power law, which is consistent with Malawi's relatively thick seismogenic layer (30–40 km), low (&lt;8%) regional extensional strain, and regional deformation localization (50%–75%) across relatively long hard‐linked border faults. Cumulatively, we highlight the importance of integrating onshore and offshore geological and geophysical data to develop active fault databases along the EAR and similar continental settings both to understand the regional seismic hazard and tectonic evolution.

Shear-wave velocity map for Pohang Basin, South Korea, based on the P-wave seismogram method

The 2017 ML 5.4 Pohang, South Korea earthquake, which caused severe damage, raised attention to the importance of the characterization of the Pohang Basin structure and the identification of active faults. We utilize 366 seismograms recorded at 102 densely deployed seismic stations during 18 microearthquakes with ML ranging from −1.11 to 1.70. We perform the P-wave seismogram method, which has been validated in various regions using seismograms for moderate earthquakes, to estimate the time-averaged shear-wave velocity from the surface to a depth of 30 m ( VS30) in and around the basin. We perform multichannel analyses of surface waves at the 32 sites to obtain shear-wave velocity ( VS) profiles, and additionally acquire the 22 existing VS profiles within the study area. We observe that velocity seismograms predict VS30 more accurately than acceleration and displacement seismograms do. The estimated VS30 values are in good agreement with the measured VS30 values. Approximately 93.3% of the measured and estimated VS30 values are located between the ±100% difference lines. We propose a VS30 map for the vicinity of the Pohang Basin by geospatially interpolating both the measured and estimated VS30 values, which is consistent with the local topography and geology. The proposed map exhibits areas with strong VS30 contrast within the Quaternary and Tertiary sediments, which might be attributed to the existence of faults.

Fault identification scheme for hybrid multi-terminal HVDC system based on control and protection coordination strategy

To further improve the capability of fault identification for protection and adaptive reclosing, a fault identification scheme based on a control and protection coordination strategy for a hybrid multi-terminal HVDC system is proposed. The protection principle for fault isolation is constructed based on the difference of the polarity characteristic of fault current between the fault line and non-fault line in the uncontrolled fault stage and fault current limiting stage. In the adaptive reclosing stage, an active fault identification scheme based on the amplitude distribution law of the injection signal along the line is proposed. Intensive simulation studies prove the fault identification scheme can identify the fault area in various fault scenarios and identify permanent faults to carry out adaptive reclosing.

Active tectonics of the Yogyakarta area (Central Java, Indonesia): preliminary findings obtained from a tectonic-geomorphic evaluation

Throughout the island of Java, several shallow faults located in the vicinity of densely populated areas accommodate the tectonic strain generated by the subduction of the Indo-Australian Plate beneath the Sunda Plate. These faults are characterized by a poor surface geomorphological expression due to the tropical climate that masks paleoseismological evidence making the identification of active faults in this environment challenging. We present preliminary data of a tectonic-geomorphic study that aims to identify and characterize active faults in the province of Yogyakarta (Central Java) as a basis to improve seismic hazard assessment. Here we focus on the Opak fault by describing its geomorphology and structure, using field data and remote sensing-based observations to contribute to the understanding of its geometry, kinematics, and tectonic activity. We show preliminary data supporting the Opak Fault as an active SW-NE transtensional left-lateral strike-slip reactivated normal fault consisting of several parallel fault strands. Although geomorphological expression of active tectonics is poor and diffuse, we found numerous field evidence of active tectonics ranging from tilted Quaternary fluvial terrace risers, triangular facets, and linear valleys to peculiar drainage patterns that allow us to provide evidence of the Holocene activity of the Opak Fault.

Earthquake‐Spawning Faults in the Seoul Metropolitan Area and Their Seismic Implications

AbstractQuaternary faults run across the Seoul metropolitan area that is the highest population region in the Korean Peninsula. Active fault identification and seismic hazard potential assessment are crucial for public safety. Densely deployed permanent and temporal seismic stations enabled us to detect micro to small earthquakes, allowing us to identify earthquake‐spawning faults in Seoul metropolitan area. The source parameters of 455 earthquakes in 2004–2020 are refined. The Gutenberg‐Richter b value is 0.94. Dominant focal depths are 4–15 km. The focal mechanism solutions of 64 earthquakes are determined using seismic‐wave polarities and amplitude ratios. Strike‐slip earthquakes are dominant in the region. Earthquakes are clustered around the Chugaryeong fault system. The dominant strikes of fault planes range from N20°E to N45°E in the northern and southern Seoul metropolitan areas, suggesting branch fault development locally. The earthquakes in middle‐northern Seoul present N‐S directional strike‐slip motions at depths ∼7.5 km along the Chugaryeong fault, suggesting seismically active near‐vertical faults subparallel with Chugaryeong fault.

Seismic Hazard Assessment for the Korean Peninsula

ABSTRACTThe Korean Peninsula is located in a stable intraplate region with low-seismicity rates and long recurrence intervals of major earthquakes. Recent moderate-size earthquakes demonstrate possible occurrence of seismic damages in the Korean Peninsula. A probabilistic seismic hazard analysis based on instrumental and historical seismicity is applied for the Korean Peninsula. Three seismotectonic province models are used for area sources. Seven ground-motion prediction equations calibrated for bedrock condition are considered. Fault source models are not applied due to poor identification of active faults. A 500 yr long historical record of earthquakes includes moderate and large earthquakes of long recurrence intervals. The influences of model parameters are reflected through a logic-tree scheme. The process and results are verified by Monte Carlo ground-motion level simulation and benchmark tests. Relatively high-seismic hazards are modeled in the northwestern, south-central, and southeastern Korean Peninsula. The horizontal peak ground accelerations reach ∼0.06, 0.09, 0.13, 0.21, and 0.28g for periods of 25, 50, 100, 250, and 500 yr, respectively, with exceedance probability of 10%. Successive moderate-size earthquakes since the 11 March 2011 Tohoku–Oki megathrust earthquake have temporarily increased the seismic hazards in the southeastern peninsula.

Database of Active Faults in Slovenia: Compiling a New Active Fault Database at the Junction Between the Alps, the Dinarides and the Pannonian Basin Tectonic Domains

We present the compilation of a new database of active faults in Slovenia, aiming at introducing geological data for the first time as input for a new national seismic hazard model. The area at the junction of the Alps, the Dinarides, and the Pannonian Basin is moderately seismically active. About a dozen Mw &amp;gt; 5.5 earthquakes have occurred across the national territory in the last millennium, four of which in the instrumental era. The relative paucity of major earthquakes and low to moderate fault slip rates necessitate the use of geologic input for a more representative assessment of seismic hazard. Active fault identification is complicated by complex regional structural setting due to overprinting of different tectonic phases. Additionally, overall high rates of erosion, denudation and slope mass movement processes with rates up to several orders of magnitude larger than fault slip rates obscure the surface definition of faults and traces of activity, making fault parametrization difficult. The presented database includes active, probably active and potentially active faults with trace lengths &amp;gt;5 km, systematically compiled and cataloged from a vast and highly heterogeneous dataset. Input data was mined from published papers, reports, studies, maps, unpublished reports and data from the Geological Survey of Slovenia archives and dedicated studies. All faults in the database are fully parametrized with spatial, geometric, kinematic and activity data with parameter descriptors including data origin and data quality for full traceability of input data. The input dataset was compiled through an extended questionnaire and a set of criteria into a homogenous database. The final database includes 96 faults with 240 segments and is optimized for maximum compatibility with other current maps of active faults at national and EU levels. It is by far the most detailed and advanced map of active faults in Slovenia.

Active Tectonics in the Kvarner Region (External Dinarides, Croatia)—An Alternative Approach Based on Focused Geological Mapping, 3D Seismological, and Shallow Seismic Imaging Data

Active tectonics in long-lived orogenic belts usually manifests on the preexisting inherited structures. In the Kvarner region of the External Dinarides, an area with low-to-moderate seismicity related to the Adriatic microplate (Adria) northward movement, we deal with faults in predominantly carbonate rocks within tectonically complex NW-SE striking fold-and-thrust belt, which makes the identification and parametrization of the active structures challenging. Moreover, anthropogenic modifications greatly complicate access to the surface geological and geomorphological data. This paper demonstrates results of focused multidisciplinary research, from surface geological mapping and offshore shallow seismic surveys to earthquake focal mechanisms, as an active fault identification and parametrization kit, with a final goal to produce an across-methodological integrated model of the identified features in the future. Reverse, normal, and strike-slip orogen-parallel (longitudinal) to transverse faults were identified during geological mapping, but there is no clear evidence of their mutual relations and possible recent activity. The focal mechanisms calculated from the instrumental record include weak-to-moderate earthquakes and show solutions for all faulting types in the upper crust, compatible with the NE-SW oriented principal stress direction, with the stronger events favoring reverse and strike-slip faulting. The 3D spatial and temporal distribution of recent earthquake hypocenters indicate their clustering along predominantly subvertical transversal and steeply NE-dipping longitudinal planes. High-resolution shallow seismic geoacoustical survey (subbottom profiler) of the Quaternary sediments in the Rijeka Bay revealed local tectonic deformations of the stratified Late Pleistocene deposits that, along with overlaying mass-transport deposits, could imply prehistorical strong earthquake effects. Neotectonic faults onshore are tentatively recognized as highly fractured zones characterized by enhanced weathering, but there is no evidence for its recent activity. Thus, it seems that the active faults are blind and situated below the thin-skinned and highly deformed early-orogenic tectonic cover of the Adria. A strain accumulating deeper in the crust is probably irregularly redistributed near the surface along the preexisting fault network formed during the earlier phases of the Dinaric orogenesis. The results indicate a need for further multidisciplinary research that will contribute to a better seismic hazard assessment in the densely populated region that is also covered by strategic infrastructure.

Active Fault Identification by Optimization of Test Designs

Model-based fault detection and isolation (FDI) methods are used to determine faults by examining the deviation of sensed information from anticipated system trajectories. In this paper, a comprehensive model-based FDI framework is proposed to improve fault identifiability and reduce false alarms during maintenance testing. In this framework, robust maintenance tests are designed and conducted, followed by false alarm analysis. The optimal tests designed improve the identifiability of faults by manipulating system inputs to maximize information with respect to faults, in the form of sensitivities of the system outputs. Each test design is evaluated a posteriori using the system model to explore whether false alarms are plausible, given system uncertainty and measurement noise. The proposed framework is applied on two case studies that compare the identifiability of faults at nominal and optimal system test conditions. The first case study focuses on a plate fin heat exchanger with various levels of particulate fouling at steady-state and transient conditions. The second case study deals with the same type of fault but in an aircraft environmental control system with multiple sources of uncertainty.

Sub Surface Active Fault Identification on Quaternary and Tertiary Rocks using Geoelectric Method in Cilaki Drainage Basin, Southern Part of West Java, Indonesia

The geophysical surveys are needed to obtain information on subsurface geology for infrastructure development, mitigation of landslide and geothermal. Cilaki drainage basin is an area Garut Regency at southern part of West Java. The area has complex geological and the main target in development plan of Southern part of West Java. The electrical resistivity method of the Schlumberger configuration was used to identify the geological subsurface and the active fault of the study area. The measurement of the electrical resistivity was made on 7 lanes (GL 1 until GL 7). The location has a height of 195 to 925 meters above sea level with depth reaching more than 120 meters and electrical resistivity value of 6 - 450 Ω meters. Generally, the electrical resistivity value of Quaternary rock units have value between 80 and 450 Ω meters and Tertiary rock unit have value of 6 - 40 Ω meters. Based on the results of data analysis can be interpreted that the area has been deformed. This is reflected also in the geomorphology as an indication of tectonic phenomenon in the form of active faults. Quantitatively, this is reflected in the value of the mountain-front sinuosity (Smf) index which ranges 1.036 to 2.173. This phenomenon occurs in geomorphology which is composed of Tertiary and Quaternary rocks.

BUILDING COLLABORATIONS WITH BIOBANKS AND HARNESSING ELECTRONIC HEALTH RECORD DATA FOR PSYCHIATRIC GENOMICS RESEARCH

Paleoseismology, archaeoseismology, and paleotsunami studies are disciplines of modern seismology and active tectonics, that open the window to past earthquakes; earthquakes that occurred before seismometers were available and which possibly were not mentioned in any written sources. Field investigation techniques and new laboratory and modeling approaches have significantly advanced these disciplines in the past two decades. The methods applied require the trace of permanent deformation at the Earth surface or in man-made structures caused by ground movements of past earthquakes. The methods include the identification of active faults, trench excavations, shallow geophysical prospecting, coring techniques, laser scanning and photogrammetry, virtual models of structural behavior, advanced archeological techniques, and different kinds of physical dating of relevant samples. In this article, three selected examples of active faulting, i.e., the North Anatolian Fault, the Himalaya Thrust Front and the Dead Sea Fault are illustrated by published results of recent case-studies with dating of the record of past earthquakes and their successive occurrence through space and time. Catastrophic inundations on coastal regions following tsunamigenic earthquakes are preserved in the succession of deposits considered as geological archives. Earthquake damage to structures at archeological sites document the effects of seismic shaking and case specific models provide some constraint on ground motion parameters. The application of the new approaches in the study of past earthquakes has become an essential part of the seismic hazard and risk assessment.

An efficient polynomial chaos expansion strategy for active fault identification of chemical processes

This paper is concerned with a highly efficient active fault detection and isolation (FDI) framework. An auxiliary, fault-revealing input is derived by solving an optimization problem. As we implement a model-based approach, the active FDI framework is robustified against model parameter uncertainties, including parameter correlations which are common for experimentally derived parameters. Moreover, critical safety limits are considered, and an optimal process performance is fulfilled in parallel. In this work, which is an extension to our ESCAPE-2017 contribution, a novel highly effective polynomial chaos expansion (PCE) approach is used to address parameter uncertainties and to include process design parameters directly. To reduce the computational load, we combined the PCE with a least angle regression (LAR) strategy. The overall effectiveness of the novel one-shot sparse polynomial chaos expansion (OS2-PCE) concept is demonstrated by analyzing a tubular plug flow reactor illustrating the need for uncertainty and parameter correlation analysis in FDI while ensuring an optimal and safe process operation, respectively.

Characterizing the active tectonics in the Oran region (Algeria) and recasting the 1790 earthquake

In this work, we reappraise the seismogenic potential of the geologic structures in the western Tell Atlas of Algeria, considered active host to moderate to low magnitude earthquakes. The direct identification of active faults is generally a difficult task in northern Algeria. The active tectonics in the Oran Plio-Quaternary age basin (Northwestern Algeria) is analyzed and characterized through a morpho-structural study combining topographic, geomorphologic, geological, and neotectonic data. Folds and fault scarps affecting Quaternary deposits show that the region is affected by compressional deformation still active nowadays, as shown by the recorded seismic activity. Our new observations enable a better understanding of the present seismotectonic context of the Oran region, particularly with regard to the magnitude and source of the 1790 Oran damaging event. The obtained result helps to shed some light on the elusive active tectonics characterizing this coastal area, and to assess regional seismic hazard, particularly in coastal zones where large seismogenic areas straddle the onshore–offshore zones.

Active faulting in a populated low-strain setting (Lower Rhine Graben, Central Europe) identified by geomorphic, geophysical and geological analysis

AbstractThe Lower Rhine Graben (Central Europe) is a prime example of a seismically active low-strain rift zone characterized by pronounced anthropogenic and climatic overprint of structures, and long recurrence intervals of large earthquakes. These factors render the identification of active faults and surface ruptures difficult. We investigated two fault scarps in the Lower Rhine Graben, to decipher their structural character, offset and potential seismogenic origin. Both scarps were modified by anthropogenic activity. The Hemmerich site liesc.20 km SW of Cologne, along the Erft Fault. The Untermaubach site lies SW of Düren, where the Schafberg Fault projects into the Rur River valley. At the Hemmerich site, geomorphic and geophysical data, as well as exploratory coring reveal evidence of repeated normal faulting. Geophysical analysis and palaeoseismological excavation at the Untermaubach site reveal a complex fault zone in Holocene gravels characterized by subtle gravel deformation. Differentiation of tectonic and fluvial features was only possible with trenching, because fault structures and grain sizes of the sediments were below the resolution of the geophysical data. Despite these issues, our investigation demonstrates that valuable insight into past earthquakes and seismogenic deformation in a low-strain environment can be revealed using a multidisciplinary approach.

Identification of a suspected Quaternary fault in eastern Korea: Proposal for a paleoseismic research procedure for the mapping of active faults in Korea

In terms of seismic hazard in the Korean Peninsula, the occurrence of destructive earthquakes has long been overlooked because of no serious modern instrumental seismicity and lack of historical earthquake records of large earthquakes. In recent years, although the importance and uses of paleoseismological studies has significantly increased in seismic hazard assessments of critical facilities, there is still a huge lack of paleoseismological data to improve our knowledge for Korean active tectonics and relevant seismic hazards. In this study, we identified and characterized a suspected Quaternary fault in the eastern part of the Korea Peninsula based on lineament analyses, field observations, and trench surveys. We focus on a prominent lineament around the northern part of the previously reported, but not sufficiently studied, Maeup Fault. Firstly, a potential fault lineament is recognized by geomorphic expressions in a mountainous area from satellite and digital elevation model (DEM)-generated images. Then, fault-related geomorphic and hydrologic features, such as disconnected drainages, sag ponds, and asymmetric water leaking out on an artificial ditch, were observed along the lineament in the field studies. Finally, the existence of the fault is confirmed by an exposure of a 2.5m wide fault core in trench surveys. The internal structures of the fault core (i.e., slip surfaces, slickenlines, and S-C fabrics) indicate that the fault evolved via a series of slip events under a variety of tectonic settings, probably leading up to the current stress regime sustained during Quaternary. Thus our results suggest that the newly identified fault could be a Quaternary fault, and hence it is necessary to perform more paleoseismic investigations around the study region. This case study emphasizes the importance of the careful interpretation of tectonic landforms and fault zone structures in the study of active faults, and proposes a suitable research procedure for the identification of active faults in Korea.

Fault population recognition through microseismicity in Mygdonia region (northern Greece)

Seismicity in the area of Mygdonia basin (northern Greece) is lately characterized by a lack of strong events (M≥5.0) on the seismogenic faults known to have been repeatedly activated in the past. Only small to moderate magnitude earthquakes (M≤4.8) have occurred since 2000 in the area. Therefore, microseismicity is the only available information to be exploited for the identification of active faults and hazard assessment, since it may occur everywhere, as well as onto the major hazardous faults. Earthquakes recorded between 2000 and 2014 by the Hellenic Seismological Network were relocated by using the available P- and S-seismic wave arrivals in order to improve location accuracy. The VP /VS velocity ratio which was found equal to 1.78, along with station time delays, were all included in the Hypoinverse computer program. In the case of strong spatial or temporal clustering the HypoDD algorithm was employed for further improving location accuracy. The relocated seismicity was used to outline the geometrical properties of the local fault population and identify seismogenic faults deprived of a clear surface expression. Cross-sections made perpendicular to the main axis of the seismicity alignments, shed more light to the local fault network.

Neotectonic and seismotectonic investigation of seismically active regions in Tunisia: a multidisciplinary approach

Due to its key position within the Africa–Europe convergence zone, Tunisia is marked by thrusting, folding, and faulting and has a major rupture zones associated with active faults. Consequently, most of Tunisian land is seismically active with significant active deformations, showing recent seismic events and their relative surface effects. This paper reports on several aspects of the seismotectonics, historical, and present-day seismicity and places them in the general tectonic and geodynamic framework of Tunisia. Field investigations, based on an integrated multidisciplinary approach, included (1) the identification of active faults, their motion and displacement, geomorphic aspects, and scarps and their relation with the general structural map of Tunisia and (2) an extensive analysis of brittle tectonic deformation affecting Quaternary deposits in several sites throughout Tunisia. The integration of field data within the existing data related to the seismic events that took place during the last decades allowed the establishment of an earthquake distribution map, as well as major seismic zones for better understanding of the seismicity database of Tunisia. To establish microzonation maps in seismic regions such as Gafsa and its surroundings, we have analyzed surface effects and secondary structures associated with active faults and correlated them with deformation rates, reconstructed for significant seismic events. Most faults exhibited typical left-stepping en-echelon with strike-slip component pattern suggesting that Tunisia is presently subjected to NNW–SSE compression. The focal mechanism of most Tunisia earthquakes combined with the existing tectonic and structural information and reconstruction of the Quaternary stress tensor allowed (a) better understanding of seismic zoning, (b) provided better assessment of the seismic hazard, and (c) facilitated the interpretation of the relationship between seismic zones and the geodynamic African–Eurasian plate boundary.

Determination of directions of horizontal principal stress and identification of active faults in Kachchh (India) by electromagnetic radiation (EMR)

Abstract The Kachchh basin in the western India is known for its recent high seismicity. This study presents an application of the geogenic Electromagnetic Radiation (EMR) technique for deciphering the directions of principal horizontal stress in the eastern Kachchh. The principal direction of horizontal stress obtained from EMR differs from those obtained from earthquake focal plane solutions. The major horizontal principal stress based on the EMR study shows an azimuth of N60°E ± 10°. The principal directions of EMR emissions are parallel to the acute bisector of conjugate microcracks. The azimuthal distribution of EMR signal and dimension of microcracks suggest that the EM emissions are transversely polarized. The study also deals with the first application of electromagnetic radiation emissions to identify active fracture planes in sandstones that could become potential active faults later, which might be seismogenic or nonseimogenic. This study is based on linear profiling at six different places across two major faults, the Kachchh Mainland Fault (KMF) and the South Wagad Fault (SWF) in the eastern Kachchh. Anomalously, high EMR emissions are observed in the eastern part of the KMF, indicating active surface deformation.