Geological investigations continue to provide critical insights into fault behavior and earthquake recurrence. Paleoseismological trenching, high-resolution coring, structural geology, tectonic geomorphology, and geodesy extend the earthquake record from recent events to multi-millennial timescales, enabling the characterization of earthquake source parameters and long-term fault behavior. These multidisciplinary observations, when combined with physics-based and multi-cycle earthquake simulations, offer new opportunities to address epistemic uncertainties, capture complex rupture processes, and refine time-dependent hazard models.
The session aims to foster dialogue on how innovative approaches and diverse datasets can be integrated into seismic hazard frameworks, ultimately improving our ability to quantify uncertainties and support applications ranging from building codes and land-use planning to insurance and risk management.
Topics of interest include, but are not limited to:
• ERF approaches and their role in PSHA and FDHA
• Advances in physics-based earthquake cycle simulations
• Incorporation of paleoseismological and geological constraints into hazard models
• Structural geology, tectonic geomorphology, and geodesy applied to fault characterization
• Methods to quantify and reduce epistemic uncertainties in hazard assessments
• Case studies linking recent earthquakes, long-term fault behavior, and hazard analysis
We particularly encourage contributions that present innovative, integrative, and multidisciplinary approaches to studying active faults and their role in seismic hazard assessment.
The North Anatolian Fault Zone (NAFZ) is a region of high seismic risk and significant tectonic complexity. In such regions, different magnitude scales provide complementary insights into the physical properties of seismic wave propagation. However, achieving reliable seismic hazard assessment remains challenging due to non-homogeneous magnitude reporting and the potential bias introduced by linking short-period magnitudes (ML) to moment magnitude (Mw). To address these inconsistencies and improve source characterization, this study presents an integrated seismological and geodetic framework. Our primary objective is to develop a robust, homogeneous Mw catalog focusing on events ranging from Mw 3.5 to 6.0. To achieve this, we employ the Coda Calibration Tool (CCT), applying the empirical envelope-based method developed by Mayeda et al. (2003). Unlike traditional direct wave analysis, this method utilizes the stable, scattered energy of coda waves to effectively mitigate path and site effects caused by lateral heterogeneity in the crust across diverse tectonic settings. By constraining the calibration with independently derived Mw from moment tensor inversion for low frequencies and apparent stress (σA) for high frequencies, we successfully lower the threshold for reliable Mw and radiated energy estimation. Moreover, we validate this seismological approach by conducting geodetic modeling for two significant events: the 23 November 2022 Mw 6.0 Düzce and the 18 April 2024 Mw 5.6 Tokat earthquakes. We perform Interferometric Synthetic Aperture Radar (InSAR) analysis using pre- and post-earthquake ascending and descending Sentinel-1 images to create a coseismic deformation map, invert using Okada elastic dislocation modeling to obtain source parameters such as fault slip distribution, and then calculate Mw. The results demonstrate remarkable consistency between Mw values derived from CCT and InSAR. Furthermore, our analysis reveals evidence for non-self-similar source scaling in the NAFZ. We observe that σA increases with seismic moment (M0), suggesting that larger earthquakes radiate energy more efficiently. Additionally, the apparent stress estimates are systematically lower than in other active tectonic regions, indicating a potentially low-seismic-efficiency environment. This multi-physics framework thus produces a homogeneous catalog for refining seismic hazard assessments and provides fundamental new insights into the rupture physics of the NAFZ.
How to cite: Tekiroğlu, G., Kaya Eken, T., Mayeda, K., Roman-Nieves, J., and Eken, T.: Seismological and Geodetic Insights on the North Anatolian Fault Zone through Coda Calibration and InSAR Techniques, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-1217, https://doi.org/10.5194/egusphere-egu26-1217, 2026.
Declustering of earthquake catalogs is a fundamental preprocessing step in seismicity analysis and probabilistic seismic hazard assessment (PSHA), as it aims to separate background, approximately Poissonian seismicity from dependent events such as foreshocks and aftershocks. The choice of declustering method can significantly influence estimated seismicity rates, b-values, spatial source models, and ultimately seismic hazard results. Despite its widespread use, there is no consensus on the most reliable declustering approach, and different algorithms often produce substantially different background catalogs for the same dataset. This study presents a systematic comparison of commonly used declustering techniques, including the window-based methods of Gardner and Knopoff, Uhrhammer, and Grünthal; the interaction-based Reasenberg algorithm; the nearest-neighbor clustering method of Zaliapin; and Epidemic-Type Aftershock Sequence (ETAS) based stochastic declustering. All methods are applied to the same regional earthquake catalog with consistent magnitude completeness and spatial coverage to ensure a fair comparison. The resulting declustered catalogs are evaluated in terms of the fraction of events classified as background, their temporal and spatial distributions, and their impact on magnitude-frequency relationships. To assess the reliability of each declustering approach, we use the ETAS model as a reference framework. The comparison reveals pronounced method-dependent variability, particularly at short inter-event times and distances, with window-based methods generally removing a larger proportion of clustered events and interaction-based methods showing sensitivity to user-defined parameters. The Zaliapin method offers a data-driven alternative but may be influenced by spatial heterogeneity, while ETAS-based stochastic declustering provides a probabilistic and internally consistent representation of seismicity at the cost of higher computational and data-quality requirements. The results highlight the need for careful method selection and uncertainty-aware declustering in seismic hazard applications and demonstrate the value of ETAS-based diagnostics as an objective benchmark for evaluating declustering performance.
How to cite: Omkar, O., Sharma, S., Nandan, S., and Mannu, U.: Comparison and reliability of declustering methods evaluated using an ETAS framework, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-2193, https://doi.org/10.5194/egusphere-egu26-2193, 2026.
Paleoseismological evidence along the El Salvador Fault Zone (ESFZ) suggests the potential occurrence of earthquakes exceeding Mw7, raising critical questions about the seismic hazard of this complex strike-slip fault system in Central America. Here, we present the first application of physics-based earthquake cycle modelling to this region, aiming to assess whether such large events are physically plausible and to explore how fault-system complexity and frictional properties control seismicity patterns.
We perform long-term earthquake simulations using the MCQsim code (Zielke and Mai, 2023) on three alternative 3D fault models of the ESFZ, characterized by increasing structural complexity. Fault geometries, slip rates, and rakes are constrained using published geodetic, geological, and geomorphological data. A systematic sensitivity analysis explores the role of the critical slip distance (Dc) and the dynamic friction coefficient (μd) into the simulated seismicity statistics. Synthetic seismic catalogues are analysed, globally and segment-by-segment, in terms of maximum magnitude, interevent times, and frequency-magnitude distributions.
Preliminary results, illustrated here for the simplest fault model and based on 10,000-year-long simulations for a systematic sensitivity analysis, indicate that maximum earthquake magnitudes strongly depend on frictional properties, while the critical slip distance mainly controls seismicity rates. Earthquakes exceeding Mw 7 are obtained only for low dynamic friction, associated with larger stress drops and more energetic ruptures. Increasing Dc reduces the number of small and moderate events, leading to longer interevent times and frequency–magnitude distributions that tend toward a characteristic earthquake behaviour.
Ongoing work focuses on validating preferred synthetic catalogues for the different fault system complexity against instrumental seismicity and paleoseismological constraints in the ESFZ, including frequency-magnitude relations, recurrence intervals, magnitude-slip scaling, and rupture characteristics of the 2001 Mw6.6 earthquake. Overall, this study provides new insights into fault segment interaction, rupture jumping, and stress transfer along the ESFZ, contributing to improved seismic hazard assessment and supporting emergency management strategies in El Salvador and the broader Central American region.
How to cite: Herrero-Barbero, P., Álvarez-Gómez, J. A., Zielke, O., Martínez-Díaz, J. J., Alonso-Henar, J., Gómez-Novell, O., and Béjar-Pizarro, M.: Controls of fault-system complexity and friction on seismicity in the El Salvador Fault Zone: results from physics-based earthquake cycle simulations, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10544, https://doi.org/10.5194/egusphere-egu26-10544, 2026.
Study on Co-seismic Response and Variation Mechanism of Water Level in the Myanmar Earthquake
Underground fluid is a kind of medium with fast flow, wide distribution and sensitive reaction stress change, which is also one of the main observation method of earthquake precursor. There are many anomalies in underground flow during earthquake pridiction. At the same time, the occurrence of earthquake also have a great impact on the observation of underground fluid. In particular, the larger the magnitude of the earthquake, the greater impact on the underground fluid.
Underground fluid observations near the epicenter, including observation wells, hot springs, and fault gas, show different changes after the major earthquake. Some of these changes can recover to the normal observation values within minutes to days after the earthquake. However, other observation wells will show completely different changes from the previous observation value.
The MW7.8 magnitude earthquake that occurred in Myanmar on March 28, 2025, led to co-seismic response changes in water levels and temperatures in multiple observation wells in the Yunnan province of China. According to statistics, a total of 127 water level and 66 water temperature observation wells in the Chinese mainland showed different forms of co-seismic responses. Among the 127 water level co-seismic response changes, 92 showed fluctuations, 11 showed step decreases, and 24 showed step increases; among the 66 water temperature co-seismic responses, 33 showed fluctuations, 11 showed step decreases, and 22 showed step increases. Among these 68 step increase or step decrease changes, 21 had not returned to their original change patterns even one month after the earthquake.
These co-seismic response changes were mainly distributed in the southwestern region of China, the Beijing-Tianjin-Hebei region, and the Tan-Lu Fault Zone. These three regions all have the characteristics of enough observation wells and complex tectonics. Particularly in the Yunnan province, a concentrated distribution of co-seismic response step changes was observed in the area of Baoshan-Dali-Chuxiong, indicating a relatively significant change in the underground tectonic stress state environment. This can also serve as an important basis for predicting the location of future moderate to strong earthquakes. The 5.0 magnitude earthquake that occurred in Eryuan, Yunnan on June 5, 2025, happened within the concentrated area of co-seismic responses caused by the Myanmar earthquake, which confirmed this inference.
How to cite: Tian, L., Zhou, Z., Yan, W., and Ma, Y.: Study on Co-seismic Response and Variation Mechanism of Water Level in the Myanmar Earthquake, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-11946, https://doi.org/10.5194/egusphere-egu26-11946, 2026.
The east-west-trending, north-dipping Dauki Fault System (DFS) is among the well-identified active fault systems in the North-Eastern part of India, and it marks the southern geological boundary of the Shillong Plateau, separating it from the Bengal alluvium basin and Sylhet trough. With a length of about 350 km stretching from about 89.9° E to 93° E, DFS is reverse in nature and can be divided into 4 segments, namely, Western, Central, Eastern and Easternmost with variable dip and strike values. Mitra et al. (2018) has indicated that this fault can produce an Mw ∼8 earthquake.
Fault segmentation, fault connectivity, and multi-segment rupture scenarios have been explicitly incorporated into a fault-system-based probabilistic seismic hazard framework for the Dauki Fault System. The SHERIFS (Seismic Hazard and Earthquake Rates In Fault Systems) methodology has been employed to enforce a global magnitude–frequency distribution while converting geological and geodetic slip rates into earthquake rates at the system scale. To account for geometric complexities such as bends and step-overs, a range of rupture hypotheses has been explored, including single-segment ruptures, partial multi-segment ruptures, and through-going system-wide ruptures. Epistemic uncertainties associated with maximum magnitude, rupture connectivity, slip-rate variability, and off-fault seismicity have been quantified using a logic-tree approach.
The resulting earthquake rupture forecasts are tested against available seismicity data of the region. The findings underscore the critical role of fault interactions in determining the seismic hazard along the DFS and indicate the need for system-level modelling to provide a reliable assessment of seismic hazard.
This study is the first to offer a seismic hazard framework based on the multi-rupture scenario for the Dauki Fault System and it also contributes to the improvement of seismic risk assessment for northeastern India and the Indo–Burman–Shillong tectonic domain.
How to cite: Pandey, A. K., Venkitanarayanan, R., and Sharma, M. L.: Multi-rupture Fault-based Seismic Hazard Assessment for the Dauki Fault System, Northeastern India, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16763, https://doi.org/10.5194/egusphere-egu26-16763, 2026.
The identification and characterization of active and capable faults are essential for subsurface modelling and seismic hazard assessment. In tectonically active areas such as the Southern Apennines, where large historical earthquakes have occurred (Mw ≥ 6.0), detailed fault investigations are critical. Surface ruptures linked to the Monte Marzano Fault System were observed during the most significant earthquakes of the last century in this region, including the 1980 Ms 6.9 Irpinia earthquake. This study presents a geophysical investigation aimed at detecting fault segments crosscutting the Quaternary sediments that fill the Pantano di San Gregorio Magno (PSGM) intramountain basin, in the Irpinia region.
The geophysical survey targeted a depth range of 25–150 m to image the basin fill and underlying bedrock. The survey was conducted using the FullWaver System (IRIS® Instruments), marking the first time that a 3D FullWaver-based resistivity and induced-polarization survey has fully covered the PSGM basin. The equipment included wireless dual-channel digital receivers and a 5-kW time-domain induced-polarization transmitter, providing flexibility for data acquisition across rugged terrain and minimizing logistical constraints.
After an extensive statistical quality check, considering acquisition conditions and lithological responses, the data were filtered and a robust inversion was executed using ViewLab software. These processes produced a detailed 3D resistivity model of the basin, integrated with a geological model to deliver an accurate view of its architecture. The results enabled the detection of fault segments concealed beneath Quaternary deposits, in agreement with available reflection seismic data. Moreover, induced-polarization data confirmed earlier evidence of degasification anomalies along the surface rupture associated with the 1980 earthquake.
Our findings highlight the effectiveness of deep resistivity tomography performed with wireless acquisition systems as an effective approach for imaging intramountain basins. Beyond methodological advances, these results provide critical constraints for fault-based seismic hazard models, improving the characterization of fault geometry and potential rupture zones in carbonate-dominated settings.
How to cite: Lucci, N., Zambrano, M., Bruno, P. P., Volatili, T., Arellano, H., Eriza, J., Marincioni, P., Matarozzi, M., Mateus, Y., Ramos, S., and Ferrara, G.: 3D full-waveform geoelectrical imaging of the Pantano di San Gregorio Magno basin (Irpinia region, Italy): constraining fault geometry for surface-rupture seismic hazard assessment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18486, https://doi.org/10.5194/egusphere-egu26-18486, 2026.
Earthquake rupture propagation across step-overs plays a critical role in controlling the extent of multi-fault ruptures and the final earthquake magnitude. For normal-fault systems, however, the key factors governing rupture-jump potential remain far less investigated than for strike-slip or thrust faults. Assessing rupture behavior in normal fault systems is critical, particularly in tectonically active regions such as Nevada (USA) (Wernicke et al., 1988), the Corinth Rift (Greece) (Bell et al., 2009), the East African Rift System (Ebinger and Sleep, 1998), and the Italian Apennines (Ghisetti and Vezzani, 2002; Faure Walker et al., 2021). These regions are characterized by damaging seismic activity involving multi-segment normal fault ruptures.
In segmented fault systems, rupture may initiate on one fault segment (the emitter) and potentially propagate onto a neighboring segment (the receiver) through dynamically evolving stress perturbations. Using a suite of three-dimensional dynamic rupture simulations performed with SeisSol (Gabriel et al., 2025), this study systematically explores the physical conditions that enable rupture jumps across normal-fault step-overs. We examine the influence of pre-stress level, fault spacing, relative fault positioning, and regional stress orientation. Our results show that rupture jumps across gaps of up to 5 km remain dynamically feasible, and that triggered secondary ruptures can evolve into sustained run-away events when fault segments overlap, even at low pre-stress levels. For such cases, the relative positioning between fault segments is fundamental. In contrast, non-overlapping fault configurations restrict successful rupture jumps to distances of less than 3 km. Fault overlap and proximity, however, introduce strong stress-shadowing effects that decrease slip and limit final earthquake magnitudes, revealing a fundamental trade-off between rupture-jump potential and energy release. Fault geometry exerts a first-order control: configurations in which the receiver fault lies within the hanging wall of the emitter fault consistently exhibit higher rupture-jump potential, more frequent sustained secondary ruptures, and larger magnitudes. Comparisons with static Coulomb stress-change predictions demonstrate that static criteria systematically overestimate rupture connectivity, as they fail to capture transient wave interactions, rapid stress reversals, depth-dependent sensitivity, and stopping-phase effects that govern dynamic triggering. These findings highlight the limitations of static stress-based approaches in seismic hazard assessment and underscore the necessity of dynamic modeling to realistically evaluate multi-fault rupture potential in normal-fault systems.
These results are partly motivated by the 2016 Amatrice-Norcia earthquake sequence in Central Italy. Our simplified fault configuration is inspired by the geometry of the Monte Vettore and Laga faults, which ruptured in two major events rather than as a single through-going rupture. In this configuration, the presence of a small gap (3-5 km between faults) and the absence of along-strike overlap between segments tend to inhibit rupture jumps, according to our simulations. As a result, dynamically triggered secondary ruptures occur only under favorable conditions and generally leads to self-arrested secondary ruptures. This provides a plausible dynamic explanation for why rupture did not propagate across the entire fault system in a single event, but instead occurred as a sequence of distinct earthquakes.
How to cite: Hok, S., Sanchez-Reyes, H., Scotti, O., and Gabriel, A.-A.: When Earthquakes Cross the Gap: Physics-based Dynamic Modeling of Step-Over Jumps in Normal Faults., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18759, https://doi.org/10.5194/egusphere-egu26-18759, 2026.
Taiwan is situated in a highly active tectonic zone where dense active faults pose significant risks of permanent ground deformation to critical infrastructure, particularly reservoirs and dams located in the near-fault domain. While Probabilistic Seismic Hazard Analysis (PSHA) regarding ground motion is well-established in Taiwan, a systematic framework for Probabilistic Fault Displacement Hazard Analysis (PFDHA) remains to be developed. This study aims to establish a PFDHA framework tailored to Taiwan's geological setting by evaluating the applicability of existing international empirical models against local observation data and generating the first Fault Displacement Hazard Map for the region.
To select the most appropriate prediction models for Taiwan, we analyzed high-resolution surface rupture data from two significant recent events: the 2018 Mw 6.4 Hualien earthquake and the 2022 Mw 6.9 Chihshang (Taitung) earthquake. We compared these observations against a suite of international empirical prediction equations, ranging from established models (e.g., Petersen et al., 2011) to the most recent developments (e.g., Lavrentiadis et al., 2023; Kuehn et al., 2024; Visini et al., 2025; Chiou et al., 2025). Through statistical analysis, we evaluated the goodness-of-fit of these models across different fault types and magnitudes to identify those that best capture the rupture characteristics of Taiwan's complex fault systems.
Based on the model comparison results, we utilized the OpenQuake engine to compute a preliminary island-wide Fault Displacement Hazard Map for Taiwan. Furthermore, we conducted a site-specific PFDHA for a reservoir located adjacent to an active fault, deriving displacement hazard curves for engineering applications. This study highlights the comparative performance of cutting-edge international models in the Taiwan region and provides a crucial empirical foundation for future infrastructure design and risk mitigation in areas prone to fault displacement.
How to cite: Gao, J.-C., Chou, M.-L., and Chen, Y.-S.: Development of a PFDHA Framework for Taiwan: Comparative Assessment of Models using Recent Surface Ruptures and Hazard Mapping, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20126, https://doi.org/10.5194/egusphere-egu26-20126, 2026.
Surface fault displacement poses significant risks to critical infrastructure, including dams, pipelines, and nuclear facilities. Despite advances in probabilistic fault displacement hazard assessment (PFDHA) methodologies over the past two decades, the lack of unified, open-source computational platforms has hindered standardized application and reproducibility. This study presents a comprehensive PFDHA framework integrated within the OpenQuake Engine, providing a standardized platform for fault displacement hazard calculations.
The framework follows the earthquake approach proposed by Youngs et al. (2003), implementing four interchangeable computational modules: (1) primary surface rupture probability, (2) primary fault displacement, (3) secondary surface rupture probability, and (4) secondary fault displacement. This modular architecture enables flexible model selection and facilitates sensitivity analyses across different modeling assumptions.
The implementation integrates state-of-the-art models from diverse sources: models developed through the Fault Displacement Hazard Initiative (FDHI), global empirical regressions derived from updated worldwide databases, region-specific models calibrated for Japan, Australia, and the Western United States, and physics-based numerical approaches. The comprehensive model library comprises 25 models across four categories, validated against International Atomic Energy Agency (IAEA) benchmarking studies and applicable to normal, reverse, and strike-slip faulting mechanisms.
The framework produces hazard curves expressing annual frequency of exceedance versus displacement amplitude, and hazard maps depicting spatial distribution of displacement at specified return periods. Application to the Calabria region of Italy, including critical dam sites, demonstrates the platform's capability to assess both principal and distributed displacement hazards for infrastructure. Results highlight the dominant contribution of principal faulting near fault traces and the sensitivity of hazard estimates to model selection.
This work represents a significant step toward establishing a standardized, transparent, and reproducible platform for PFDHA, addressing the current lack of unified computational tools in the seismic hazard community.
How to cite: Chen, Y.-S., Pagani, M., Peruzza, L., and Fernandez, H.: Towards a Unified PFDHA Platform: OpenQuake Engine Implementation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20524, https://doi.org/10.5194/egusphere-egu26-20524, 2026.
Northern Calabria (Italy) is an area with significant historical seismicity (Pollino / Sila Massif). While seismic hazard is now commonly assessed at both local and regional scales, fault displacement hazard also represents an important concern, particularly for critical infrastructure such as dams, bridges and nuclear facilities. In recent years, many efforts have focused on developing PFDHA (FDH initiative; IAEA benchmarks, etc.), leading to the development of several new prediction models.
In this study, we present a regional-scale assessment of fault displacement hazard, using an updated seismotectonic model derived from national fault databases (DISS, ITHACA) and published literature. We identify 11 potential seismogenic sources, of which 10 show normal kinematics and 1 is strike-slip. From these 11 potential sources, we explore 4 alternative source configurations, to account for uncertainty in fault activity.
For the hazard calculations, we test various prediction models for surface rupture and surface displacement, for both ‘principal’ and ‘distributed' faulting. These models use different displacement metrics (AD/MD) and faulting definitions (principal, distributed, sum-of-principal, aggregated), making a direct inter-model comparison difficult. In addition to the regional-scale analysis and to overcome faulting definitions inconsistencies, we also investigate specific potentially critical sites (dams and bridges), enabling a more comprehensive comparison among models.
Results indicate that the fault displacement hazard is generally low, with return periods for significant displacement values (>10 cm) largely exceeding 10 kyr. The hazard is the highest along the surface fault traces (principal faulting) and decreases rapidly with distance from them (distributed faulting), emphasising the importance of having a reliable knowledge of surface traces of active and capable faults. We also highlight the high model variability, demonstrating the importance of using a logic-tree approach.
How to cite: Fernandez, H., Chen, Y.-S., Testa, A., Pace, B., Boncio, P., and Peruzza, L.: Probabilistic Fault Displacement Hazard Analysis study in northern Calabria (Italy), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21248, https://doi.org/10.5194/egusphere-egu26-21248, 2026.
The inadequate characterization of buried faults may lead to unexpected damage resulting from the earthquakes they are capable of generating. Therefore, multi-disciplinary approaches that incorporate buried faults into seismic hazard and risk assessments have gained increasing attention both in national and international literature. Post-earthquake investigations following the Van Earthquake and the 2023 Kahramanmaraş earthquakes in Türkiye indicate the necessity of characterization of tectonic structures.
This study aims to evaluate the potential buried continuation of the Misis Fault, one of the major elements influencing the structural evolution of the Adana Basin, based on geological and geophysical datasets. The investigation was carried out within the framework of the project entitled “Identification of Buried Faults Using Geophysical Methods”, conducted by the General Directorate of Mineral Research and Exploration (MTA) of Türkiye. The geometry and spatial spatial extent of the fault were examined using multiple geophysical methods.
During the investigation process, surface observations related to the fault were evaluated to interpret its kinematic characteristics and possible activity from the geological point of view. Drone-borne magnetic surveys, high-resolution UAV-derived orthophotos and 2D seismic reflection data were combined together in the segments where surface morphology are limited. As a result of the integrated evaluation of field studies and geophysical data, outcomes suggesting the presence of structural discontinuities responsible for deformation within the Quaternary basin fill that are not directly observable at the surface. These discontinuities indicate a northward continuation of the Misis Fault beneath the Adana Basin. Furthermore, a previously unrecognized structure striking approximately N20ºW was identified within the basin based on the seismic profiles and orthophoto analyses. This structure, named the Tumlu Segment, is interpreted as a newly segment of the Misis Fault System.
In summary, the combined geological and geophysical results provide new insights into the buried continuation of the Misis Fault within the Adana basin. This finding should contribute to regional-scale seismic hazard and risk assessments.
Keywords: Buried faults, 2D seismic reflection, Drone-borne magnetic survey, orthophoto, Adana Basin, Misis Fault, Tumlu Segment
How to cite: Kurt, B. B., Gürboğa, Ş., Doğan, Ş., Kıyak, A., Köksal, S., Demir, S., Ayrancı, A., Bakar, M. L., Yılmaz, Y., Kürkçüoğlu, B., Hacısalihoğlu, Ö., Karakulak, G. E., Öztürk, B., Apatay, E., Akyol, Z., Ak, E., Izladı, E., Kaplan, S., Şırayder Şirin, S., Erol, E., Can Turan, S., and Çetin, F. E.: Multi-approach study for buried fault and its seismic risk assessment, Misis fault, Adana Türkiye, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-22133, https://doi.org/10.5194/egusphere-egu26-22133, 2026.
Posters virtual: Tue, 5 May, 14:00–18:00 | vPoster spot 1b
EGU26-20741 | ECS | Posters virtual | VPS24
A seismogenic modelling approach for rift-basin fault systems in slow-deforming regions: application to the western margin of the Valencia TroughTue, 05 May, 14:21–14:24 (CEST) vPoster spot 1b
Seismic hazard assessment is crucial for the design of critical facilities, whose damage could lead to severe consequences. The design of such facilities typically requires the definition of seismic actions associated with recurrence periods on the order of 5,000-10,000 years. Earthquakes with such low frequencies are well documented in highly deforming regions, where paleoseismic records commonly encompass several seismic cycles of active faults. In contrast, in slow-deforming regions or areas of low seismicity, the scarcity of seismic data hinders the definition of seismogenic zones. In this context, geological studies of active seismogenic faults are essential, as they allow the characterisation of seismic behaviour over time spans far exceeding those covered by instrumental or historical records. These data can contribute to constraining fault’s seismic cycles and estimating earthquake magnitude–frequency distributions at the fault scale.
Despite their importance, the incorporation of faults into seismic hazard models remains challenging, particularly in low strain regions such as the western margin of the Valencia Trough. This region of the NE of Iberia (from the Vallès-Penedès Graben to the Valencia Depression) corresponds to a passive margin characterised by a basin-and-range structure, bounded by multiple NNE–SSW-oriented normal faults formed during the Neogene rifting episode. Those faults are usually associated with mountain fronts, although our recent studies have found some new faults crosscutting Pleistocene alluvial fans. These newly discovered faults are being studied by means of geomorphology, geophysics, paleoseismology and geochronology in order to estimate their seismic parameters. Several challenges arise when analysing these faults, including fault identification, incomplete geological records, and the need for complex dating techniques.
Moreover, in regions characterised by fault systems, fault interactions may play a significant role. In regions such as the studied area, these interactions may result in long quiescent periods followed by phases of increased activity or even cascading events. Under such conditions, distinguishing between quiescent and active phases is especially difficult, as recurrence intervals are expected to span several thousands of years in both cases.
In this work, we explore existing methodologies for the computation of seismic hazard incorporating geological data from faults and fault systems in slow-deforming regions, using the western margin of the Valencia Trough as a case study. To this end, a detailed geometric characterization of the fault system is carried out to establish the geometric relationships among faults. Recent morphotectonic analyses and newly acquired geological data are then used to constrain the seismic parameters of the studied faults and to estimate their earthquake frequency distributions. Finally, several alternative seismic source models are proposed, forming the basis for the construction of a logic tree for subsequent seismic hazard calculations. These
models, although in progress, provide a framework for improving seismic hazard assessments in slow-deforming regions, contributing to safer design of critical infrastructure.
How to cite: Ollé-López, M., García-Mayordomo, J., Scotti, O., and Masana, E.: A seismogenic modelling approach for rift-basin fault systems in slow-deforming regions: application to the western margin of the Valencia Trough, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20741, https://doi.org/10.5194/egusphere-egu26-20741, 2026.
