Earthquake Source Research Articles

2023 Earthquake Doublet in Türkiye Reveals the Complexities of the East Anatolian Fault Zone: Insights from Aftershock Patterns and Moment Tensor Solutions

Abstract The East Anatolian Fault Zone (EAFZ) is a 700-km-long left-lateral transform fault system along the boundary between the Anatolian and Arabian plates. In the interseismic period, the eastern segments of the EAFZ display relatively uniform seismic activity, whereas the western segments exhibit seismic gaps, localized clusters, and extensive diffuse zones. Hence, our understanding of the geometry and kinematics of the western and northern segments remain limited. The occurrences of the 6 February 2023 Mw 7.8 Kahramanmaraş on the main branch and Mw 7.6 Elbistan earthquakes on the northern branch have led to complex aftershock activity shedding light on the nature of these relatively silent segments. In this study, to better understand the complexities of the fault, we constructed a comprehensive catalog of ∼32,000 earthquakes that occurred between 6 February 2023 and 30 March 2023, using a deep-neural-network-based picker. In addition, 170 earthquake source mechanisms with Mw 3.5+ were obtained from regional moment tensor inversion. The spatial distribution of the aftershocks shows that most of the activity clusters around the fault bends and major depressions. Previously unmapped and inactive secondary faults of varying lengths are identified within these geometrical complexities. The new seismological observations provide compelling evidence of extension along the Karasu valley, compression occurring along the Erkenek segment, reactivation of basin faults near the Narlı fault zone and the persistent shallow seismic creep of the Pütürge segment. The analysis of seismicity and earthquake source mechanisms along the northern branch reveals the structures of previously inactive faults, both near the extensional Göksun bend in the west and the compressional Nurhak fault complex in the east. In summary, we illustrate the intricacies of previously quiet segments of the EAFZ and aim to gain a deeper understanding of how secondary faults and geometrical discontinuities along the EAFZ played a role in shaping the 2023 Türkiye doublet earthquakes.

Double-Difference Method for Relocating the Hypocenter of Aftershock Earthquakes in Seririt Singaraja

A method that does not require a main earthquake (master event) that can be used simultaneously to relocate a very large number of earthquakes with wide hypocenter separation is called the double-difference method. A method used to relocate the aftershocks in Seririt Singaraja on November 14 2019 with coordinate positions 113.478 – 115.181 East Longitude and 8.357 – 7.894 South Latitude. The earthquake data used in this research was accumulated from 85 BMKG seismic stations. Data analysis uses cross-correlation time differences which can increase the accuracy of travel time between the receiving station and the earthquake, thereby reducing errors in calculations. The double difference method used to relocate the earthquake in the Seririt Singaraja area showed that there was a shift in the location of the earthquake hypocenter before and after it was relocated. Horizontally and vertically, the distribution of earthquake hypocenters before and after being relocated occurs when there is a collection of location shifts. The results of this research were able to relocate 152 aftershocks properly. The main earthquake after being relocated was at a depth of 17 km, while the distribution of aftershocks was at a depth of around 6-25 km, so that it can more accurately describe the position of the earthquake source and is able to show clearer and easier to interpret structural patterns.

The NE-SW Sibari fault zone: A seismic hazard source in Ionian Northern Calabria (Italy)

A multidisciplinary approach including archaeological, geophysical, and geological/geomorphological surveys provided pieces of evidence that allowed us to identify the Sibari fault zone (SFZ) in Northern Calabria (Italy). The SFZ runs in a ∼ NE-SW direction for a length of ∼18 km from the Ionian coastline to Terranova da Sibari and has an oblique normal-dextral kinematics. The envelope of the SFZ is derived from several direct and indirect evidence resulting in subparallel and locally en-echelon fault traces over a maximum 500 m-wide band, running at different elevations across hills and flat lands. The SFZ was active since at least the Middle-Upper Pleistocene, producing faulting of alluvial deposits, marine terraces, drainage incisions, and the archaeological structures of Sybaris. Given the fault length and assuming a seismogenic behavior, the SFZ is a primary earthquake source possibly producing moderate to large earthquakes (M ≥ 6). We calculated the average slip rates along the SFZ based on the ages and on the accumulated displacements of offset streams and marine terraces. The estimates are of 0.05–0.18 mm/yr and 0.41–0.70 mm/yr for vertical and dextral slip, respectively. Based on both the measured (min. 30 cm) and the expected value (av. 40 cm) of lateral slip per event, we infer an average recurrence for surface faulting events on the SFZ of about 700–1000 yrs. The most recent surface faulting earthquake occurred on the fault is dated 1300–1100 yrs. ago, highlighting that the elapsed time approaches the estimated average recurrence. Considering these findings, the newly recognized SFZ should be included among the faults that contain a potential seismic hazard in this poorly known portion of the Ionian sector of northern Calabria.

Towards a geodetic earthquake catalogue for Central America: detecting coseismic deformation in Costa Rica using Sentinel-1 InSAR

SUMMARY Earthquake source parameters can be estimated using seismological observations, but the identification of the fault responsible is often complicated by location uncertainties and the inherent ambiguity between nodal planes. Satellite Interferometric Synthetic Aperture Radar (InSAR) can be used to observe ground deformation and model fault geometry but is limited by climate conditions (water vapour) and ground coverage (dense vegetation). In the tropics, the atmosphere is dynamic and most regions are densely vegetated, making detecting coseismic deformation challenging. Here, we perform a systematic inspection of coseismic interferograms from Sentinel-1 SAR images, to assess their suitability for detecting coseismic deformation in Costa Rica. Using data from the seismological network, we target seven earthquakes between 2016 and 2020 with depths $\le \, 20$ km and magnitudes Mw 5.3–6.2. For each event, we use the seismic parameters to compute line-of-sight displacements for ascending and descending geometries and for both nodal planes and generate 12- and 24-d coseismic interferograms where available. We obtain interferograms with coseismic displacement signals for three of the seven earthquakes. We invert the geodetic data to retrieve the earthquake source parameters but the lack of offshore geodetic coverage causes trade-offs between parameters and large uncertainties. The Jacó and Golfito earthquakes likely occurred on the subduction interface and the geodetic locations were 6–9 km closer to the coast than previous seismic estimates. The Burica earthquake occurred on a shallow steeply dipping thrust fault in the outer forearc. For the other earthquakes, no coseismic deformation was detected due to atmospheric noise or poor coherence. These results demonstrate the suitability of 12-d Sentinel-1 interferograms for monitoring shallow earthquakes of magnitude > Mw 5.7 in Central America. This approach can be used to begin a surface deformation catalogue for the region, which will ultimately help improve the understanding of active deformation processes and improve hazard maps.

Complex rupture evolution of the 2007 Martinique earthquake: a non-double-couple event in the Caribbean Sea

SUMMARY A large non-double-couple component of a tectonic earthquake indicates that its rupture likely was complex and likely involved multiple faults. Detailed source models of such earthquakes can add to our understanding of earthquake source complexity. The 2007 Martinique earthquake in the Caribbean Sea is one of the largest recent earthquakes with a known large non-double-couple component. It was an intermediate depth intraslab earthquake within the South American plate where it is subducting beneath the Caribbean plate. We applied potency density tensor inversion (PDTI) to teleseismic P waves generated by the 2007 Martinique earthquake to model its source processes and focal mechanism distribution. We identified two focal mechanisms: a strike-slip mechanism with a north–south tension axis (T-axis), and a downdip extension (DDE) mechanism with an east–west T-axis. Rupture by the DDE mechanism was predominant in the northern part of the source region and strike-slip rupture in the southern part. These two focal mechanisms had approximately parallel pressure axes (P-axes) and approximately orthogonal T-axes. The seismic moments released by both types of rupture were almost equal. These results indicate that the 2007 Martinique earthquake had a large non-double-couple component. We identified five subevents with two predominant directions of rupture propagation: two strike-slip subevents propagated to the southeast and three DDE subevents propagated to the east. Although the directions of propagation were consistent for each focal mechanism, each subevent appears to have occurred in isolation. For example, the rupture of one DDE subevent propagated from the edge of the source region back towards the hypocentre. Complex ruptures that include multiple subevents may be influenced by high pore fluid pressure associated with slab dehydration. Our results show that PDTI can produce stable estimates of complex seismic source processes and provide useful information about the sources of complex intermediate depth intraslab earthquakes for which fault geometry assumptions are difficult.

An improved estimation of stress drop and its application on induced earthquakes in the Weiyuan Shale Gas Field in China

SUMMARY Stress drop is a proxy of understanding earthquake source process, and it is controversial whether the stress drops of induced earthquakes associated with hydraulic fracturing and injection activities are similar to those of tectonic earthquakes. The measurement of stress drops is usually biased due to the limitations of observation means, or hidden issues in the estimation approaches. Utilizing a local short-period seismic network, we investigate the stress drops of induced earthquakes in Weiyuan Shale Gas Field in Sichuan Province, China from 2019 to 2020. Totally 11 844 earthquakes are involved in the analysis, and their stress drops are obtained using an improved approach on the basis of the traditional spectral decomposition method combined with a global optimization algorithm to avoid stacking of spectra that is found leading to source parameter underestimation. We divide the studied area into three subareas, and the results show strong stress drop heterogeneity across the entire region. We obtain an average stress drop of 2.29 MPa, piecewise stress drop dependence to earthquake magnitude, and complex depth dependence pattern. Our results indicate that stress drops of induced earthquakes are overall consistent with the induced earthquakes in other areas as well as tectonic earthquakes in different environments. Meanwhile, the complexity in the stress drop dependence to depth possibly reflects the variability of stress drops for different earthquake triggering mechanisms.

The 2023 New Zealand Ground-Motion Database

ABSTRACT This article summarizes the development of the 2023 New Zealand ground-motion database (NZGMDB). A preceding version was formally used as the central ground-motion database in the ground-motion characterization modeling for the 2022 New Zealand (NZ) National Seismic Hazard Model (NSHM) revision. The database contains ground motions for events with a moment magnitude greater than ∼3.0 from the years 2000 to the end of 2022. Several challenges associated with NZ earthquake source metadata are explained, including determination of earthquake location, magnitude, tectonic classification, and finite-fault geometry, among others. The site table leverages the site database developed as a part of the 2022 NZ NSHM revision, and several definitions of source-to-site distance are computed for the propagation path table. The ground-motion quality classification was initially assessed using a neural network. Subsequent waveform quality verification was conducted and additional quality criteria were enforced to ensure a sufficiently high-quality database. Standard processing techniques were applied to the ground motions before intensity measure (IM) calculation. IMs in the database include peak ground acceleration, 5%-damped pseudoacceleration response spectra, smoothed Fourier amplitude spectra, and other cumulative and duration-related metrics. The NZGMDB is publicly available and routinely updated as new and higher quality data become available.

Inverzija momenta tenzora uklapanjem površinskih talasa za zemljotres M 5.5 u Kraljevu

This paper focuses on the inversion of seismic data from the Kraljevo earthquake to determine the source parameters and provide a comparison with classical methods. Understanding the earthquake source is critical for seismic hazard assessment and contributes to refining existing models. The inversion was performed using the Grond software, using seismic waveform data from the seismic stations located in the range of 900 km from the epicenter to resolve the moment tensor and other key source parameters: depth, magnitude, etc. The results for the moment tensor solution were compared with the one obtained from traditional (P-wave first-motion polarity) method as well as the source parameters were compared with findings from prior studies, offering insights into the robustness of the inversion approach. This comparison helps assess the reliability of different techniques in earthquake source analysis, enhancing our understanding of seismic events and their broader implications for regional tectonics.

On the diversity of fracture behavior in a brittle solid with sets of preexisting small-scale cracks

Understanding the multiscale fracture behavior of brittle materials is of crucial importance not only in engineering applications but also in seismology where an earthquake source, usually assumed as one single, relatively large fracture region but in reality composed of relatively smaller multiple fractures, behaves mechanically in diverse ways, emit waves with different characters and may cause a single seismic event or even a cluster of earthquakes and earthquake swarms. For understanding the complex fracture processes, by employing the experimental technique of dynamic photoelasticity with high-speed video cameras, we have been simultaneously observing global, large-scale material behavior and local, smaller-scale evolution of waves and fractures in two-dimensional linear elastic brittle polycarbonate specimens. Each specimen has sets of preexisting small-scale parallel cracks prepared by a digital laser cutter and modeling large-scale geological fault planes, and it is subjected to external (quasi-)static and impact loads. Here we show some recent examples of the diverse fracture behavior observed in brittle birefringent solid specimens under tensile/compressive external loading. The fracture behavior is considerably dependent on the loading conditions, and developing fractures do not always break the specimen in an “unzipping” way, i.e. the specimen is not always divided along a perforation line consisting of small-scale cracks. Rather, the diverse fractures can easily jump to remote places, propagate back-and-forth or reversely move in the opposite direction compared with the initial one. Our findings may play a role in comprehending the generation mechanism of a cluster of fractures in brittle solids in general.

Algorithm of the plotting earthquake occurrence rate graphs taking into account uncertainties in magnitude estimation

The study is devoted to the development of algorithms for constructing statistically based earthquake occur- rence rate graphs, which are necessary for parameterizing models of the earthquake occurrence sources in the probabilistic seismic hazard analysis. The algorithm is based on modeling a set of earthquake catalogs based on the original one with a random correction to magnitude. The final earthquake occurrence rate graph is built on the basis of a total analysis of time- completeness graphs for all model catalogs with a fixed magnitude step.

ОБ АКТУАЛЬНОСТИ И ВОЗМОЖНОСТИ ПРЕДУПРЕЖДЕНИЯ СЕЙСМИЧЕСКОЙ ОПАСНОСТИ НА ТЯНЬ-ШАНЕ

The problem of activation of the seismic regime of the Tien Shan and the possibility of strong earthquakes in its southern and northern foothills in the next few years in connection with the earthquake of January 23, 2024, which occurred in the southern foothills of the Central Tien Shan in Ushi County (Ukturpan) of Aksu Prefecture of Xinjiang Province of the People's Republic of China, an earthquake of magnitude 7.1 occurred near the city of Aksu. The Ushinsky earthquake of 23.01.2024 may mean the beginning of a new seismic activation of the Tien Shan. Here is the previous cycle of eight strongest earthquakes with M=6.9-8.3 in the northern and six with M=6.8-7.8 in the southern foothills of the Tien Shan, which lasted 100 years, began in 1885 with the Belovodsky earthquake (M=6.9 near Bishkek) and ended with the Kashgar earthquake (M = 7.0) in 1985. There was another strong Suusamyr earthquake with M = 7.3 in 1992 in the middle part of the Tien Shan, which is atypical in this region. With the earthquake of Usha, the period of calm for earthquakes with magnitudes 7.0 and more, which lasted for almost 40 years, ended. A brief overview of the current state of the issue of forecasting strong earthquakes is given. It is noted that there is a certain discrepancy between the basic concepts of the existing earthquake source models and the available geomechanical data on the fragile destruction of rocks. The latest achievements of tectonophysics in the field of studying the current stress state directly in rock massifs are presented. It is shown that, based on the results of tectonophysical reconstruction of natural stresses, it is possible to perform zoning of active faults according to the level of coulomb stresses responsible for the implementation of brittle fracture. The analysis of the results of active fault zoning performed in the foci of the strong Wenchuan earthquake (M=8.0, 2008) and the Karamushir earthquake (M=7.8, 2023) is given. The analysis of the possibilities for long-term and short-term forecasting based on a complex of seismic, seismotectonic and geophysical methods based on the results of tectonophysical zoning of active faults is performed.

Сейсмотектонические деформации и сброшенные напряжения землетрясений Центрального Тянь-Шаня

Based on the seismic moment tensor (SMT) data of 270 earthquakes in the Central Tien Shan, which occurred from 1978 to 2021 and include 63 events from the Global Centroid Moment Tensor catalog and 207 events from the works of Aleksander D. Kostyuk and Naylya A. Sycheva, the focal parameters (seismotectonic deformations (STD), kinematic and dynamic parameters, source radius, and stress drop) were calculated. The STD calculation was based on the approaches proposed in the studies of Yuriy V. Riznichenko and Sergei L. Yunga. The area under consideration is characterized by such deformation modes as thrust, transpression, underpression, and oblique. The distribution of the Lode–Nadai coefficient was calculated and plotted. A significant part of the study area is characterized by simple compression deformation, dominated by simple compression and simple shear. To calculate the stress drop , the values of the scalar seismic moment M0, which are determined in the SMT calculation, and the source radii r, which are calculated on the basis of theoretical and experimental models of the dependence of the source radius on the moment magnitude, were used. The radii r and stress drops  were calculated for two models of earthquake sources: the Brune model and the Madariaga–Kaneko–Shearer model. A catalog of dynamic parameters was compiled. The comparison of the kinematic and dynamic parameters of earthquakes was carried out, and the relationship of the dropped stresses with the type of movement in the source, as well as with the Lode–Nadai coefficient, was established. The results obtained in the study can be useful for specialists in other fields of knowledge – geodesy, geology, and geophysics.

GRAVITATIONAL GEOLOGICAL PROCESSES (KARST)

The article presents karsts, as one of the gravitational geological processes, developing in rocks (limestone, dolomite, gypsum, anhydrite, sodium and potassium salts) dissolving in natural surface and groundwater. For the first time, an attempt was made to study karsts, changes in hydrogeological conditions during their development and the influence on internal and external hazardous geological phenomena. The main purpose of this article is to draw attention to the need for further study of the Dvin earthquake source, associated with the possible collapse of underground voids (in this case, karst halls) characteristic of this territory.

Reduced micropolar half-space subjected to earthquake sources

Reduced micropolar half-space subjected to earthquake sources

Sensing Optical Fibers for Earthquake Source Characterization Using Raw DAS Records

AbstractDistributed Acoustic Sensing (DAS) is becoming a powerful tool for earthquake monitoring, providing continuous strain‐rate records of seismic events along fiber optic cables. However, the use of standard seismological techniques for earthquake source characterization requires the conversion of data in ground motion quantities. In this study we provide a new formulation for far‐field strain radiation emitted by a seismic rupture, which allows to directly analyze DAS data in their native physical quantity. This formulation naturally accounts for the complex directional sensitivity of the fiber to body waves and to the shallow layering beneath the cable. In this domain, we show that the spectral amplitude of the strain integral is related to the Fourier transform of the source time function, and its modeling allows to determine the source parameters. We demonstrate the validity of the technique on two case‐studies, where source parameters are consistent with estimates from standard seismic instruments in magnitude range 2.0–4.3. When analyzing events from a 1‐month DAS survey in Chile, moment‐corner frequency distribution shows scale invariant stress drop estimates, with an average of Δσ = (0.8 ± 0.6) MPa. Analysis of DAS data acquired in the Southern Apennines shows a dominance of the local attenuation that masks the effective corner frequency of the events. After estimating the local attenuation coefficient, we were able to retrieve the corner frequencies for the largest magnitude events in the catalog. Overall, this approach shows the capability of DAS technology to depict the characteristic scales of seismic sources and the released moment.

Seismic Hazard Assessment in Maluku Province Using PSHA

On 10 January 2023, a strong earthquake with a moment magnitude (Mw) of 7.5 occurred in Banda Sea, Maluku Province. This earthquake caused casualties around the epicentre due to the building collapse which was not an earthquake-resistant structure. A high level of seismic vulnerability and non-standard infrastructure often result in large losses when earthquakes occur. Therefore, mapping of earthquake-prone areas needs to be carried out to optimize the mitigation efforts based on Peak Ground Acceleration (PGA) and Spectrum Acceleration (SA) values. In this paper, mitigation efforts are carried out by mapping earthquake-prone areas using Probabilistic Seismic Hazard Analysis (PSHA) which considers the potential of each complex earthquake source in Maluku Province. Input data was obtained from several earthquake catalogues such as Advanced National Seismic System (ANSS), International Seismological Center (ISC), and United States Geological Survey (USGS) which were processed and analyzed using the Matlab, ZMap, and R-CRISIS programs and mapped using the ArcMap program. The results of PSHA show that Maluku Province is a region with varying levels of earthquake vulnerability. The research results show that the distribution hazard value on PGA in Maluku Province reaches 0.02g to 0.48g for a return period of 500 years and 0.04g to 0.79g for a return period of 2,500 years and on SA for periods of 0.20 seconds and 1.00 second reaches 0.04g to 0.89g and 0.01g to 0.22g for a return period of 500 years and 0.07g to 1.48g and 0.02g to 0.35g for a return period of 2,500 years, respectively. The highest level of vulnerability is in the northern region including Seram Island, Way Apu Island and Ambon Island and the lowest level of vulnerability is in the eastern region including Aru Island.

Analisis Aselerasi Riwayat Waktu pada Wilayah Spesifik di Yogyakarta dengan Sumber Gempa Subduksi Berdasarkan Peta Gempa 2002

Indonesia is a country that is very prone to earthquake disasters. Earthquakes cause damage especially to buildings. In building planning, the usual earthquake load is the earthquake load from the spectral response. The use of earthquake loads from time history is very rarely used because of the difficulty of finding accurate data for an area. In this study, Alana Hotel and Apartment were chosen as research objects to find artificial time history. All earthquake data affecting Yogyakarta region were collected from several sources. Seismic hazard analysis in this study uses the PSHA (Probabilistic Seismic Hazard Analysis) method by calculating the main earthquake only. The selection of attenuation functions is based on the similarity of geological and tectonic conditions in Indonesia. These attenuation functions produce a seismic hazard curve and a uniform hazard spectrum response. The selection of time history data for bedrock is based on the results of the deaggregation process in the form of dominant magnitude and dominant distance from the subduction earthquake source. It is necessary to adjust the spectrum response in the time history data to fit the research location. Furthermore, earthquake waves from the bedrock are propagated to the surface. The results show that the peak time history acceleration value after surface propagation increased by 1.51 times than the time history in bedrock.

Integrated tsunami risk framework considering agent-based evacuation modelling: The case of Saga, Kochi Prefecture, Japan

This study develops an integrated tsunami risk framework combining stochastic tsunami hazard and agent-based evacuation modelling. The framework is applied to the case of Saga, Kochi, Japan, with a population of ∼ 2,200 anticipated to experience significant tsunami events (∼ M9.0). First, stochastic earthquake source models are generated for two values of magnitudes (M8.8 and M9.0) and used to carry out stochastic tsunami inundation simulations. Agent-based tsunami evacuation modelling using MATSim is then performed by considering four mode scenarios: single mode (pedestrian and car) and two multimodal scenarios (mix of car and pedestrian). The stochastic tsunami simulations and agent-based evacuation modelling results are integrated to estimate the risk. The effect of existing tsunami evacuation points and tsunami evacuation towers on risk reduction is also assessed. Such an integration framework is finally used to recommend tsunami mitigation strategies in the tsunami-prone regions. Results show that a significant tsunami hazard (i.e., tsunami depth up to 15 m) is expected in the Saga district, with an arrival time between 5 and 30 min. In addition, the evacuation points on higher grounds effectively save local residents' lives, as shown by the small number of affected people, specifically for the pedestrian and multimodal models (i.e. 10-100 people, excluding the car model). However, up to ∼ 1,000 people may get affected if car is the sole mode of evacuation. Therefore, the coastal community is recommended to evacuate on foot. Finally, identifying and securing sufficient higher grounds and vertical evacuation points are essential for risk reduction.

A SERIES of TANGIBLE EARTHQUAKES in 2018–2019 in the FOCAL ZONE of the 10-point SPITAK EARTHQUAKE of 1988

The paper presents the results of a study of 2018–2019 tangible seismic events with intensity at the epicenter of 5–6 points and above, that occurred in the focal zone of the 10-point Spitak earthquake of 07.12.1988 with MLH =6.8. Two earthquakes of June 6, 2018, with МL=3.6 and МL=4.3, as well as two shocks on September 10, 2019, with МL=4.7 and with МL=3.9, were felt in the nearest settlements with an intensity of 5 or more points. For three of them, according to the collected macroseismic data, isoseist maps were constructed and macroseismic parameters were determined. The strike of the nodal planes in the earthquake sources is consistent with the direction of elongation of the isoseist system, which, in turn, for three events coincides with the strike of the nearest faults of the Pambak-Sevan system.

Near Real-Time Detection and Moment Tensor Inversion of the 11 May 2022, Dharchula Earthquake

On 11 May 2022, an earthquake of Mw 5.2 occurred in the Dharchula region of Uttarakhand Himalayas, India. The Uttarakhand State Earthquake Early Warning System (UEEWS) detected and transmitted the warning within 11.61 s from the origin time, taking only 4.26 s for processing, location, and magnitude estimation and warning dissemination. The complete analysis was performed using three seconds of waveforms. Using the initial earthquake parameters provided by the UEEWS, moment tensor inversion was performed using the broadband seismometers network installed in northern India. The moment tensor (MT) inversion was performed for the event using both the body waves and the surface waves. The first motion polarity was used along with waveform data to enhance the solution’s stability. This paper discusses the importance of real-time event detection and efforts towards real-time MT source inversion of earthquakes in the Uttarakhand Himalayas. Relocation of two past earthquakes near Dharchula is also undertaken in this study. The outcome of this study provides insights into mitigating seismic hazards, understanding earthquake source mechanisms, and enhancing knowledge of local fault structures.