Fault Geometry and Tectonic Implications of the 2026 Jalapur Sharif Earthquake, Pakistan

1. Introduction

The northwestern Himalayan foreland of Pakistan represents one of the most actively deforming tectonic regions, driven by the ongoing convergence between the Indian and Eurasian plates [1,2,3,4,5]. This convergence is accommodated through a complex system of fold-and-thrust belts, blind thrusts, strike-slip faults, and associated neotectonic structures that collectively contribute to the regional seismic hazard [6,7]. The Mirpur–Jalalpur Sharif region, located within the southeastern Potwar Plateau and bounded by left lateral Jhelum fault in East, Sarghodha high and Jhelum plain in south and Salt Range in the north.

Recent seismological investigations reported an increase in earthquake rate within the Mirpur and surroundings regions, particularly following the Mw 5.8 Mirpur earthquake of 24 September 2019 [7,8]. This earthquake was among the largest instrumentally recorded events in northeastern Pakistan in recent decades and occurred in close proximity to the Mangla Dam reservoir (Figure 1). The earthquake generated extensive socio-economic losses, causing widespread structural damage, casualties, and significant disruption to critical infrastructure [8,9,10,11,12,13,14,15,16,17]. Due to its shallow focal depth and occurrence within unconsolidated alluvial and fluvial deposits, the event triggered severe secondary geohazards, including liquefaction, lateral spreading, ground fissuring, and differential settlement [11]. These coseismic ground failures extensively affected the Upper Jhelum Canal and adjacent transportation networks, highlighting the pronounced vulnerability of engineered structures within the region [16].

The 2019 Mirpur earthquake also renewed interest in the active tectonics and stress evolution of the northeastern Potwar Plateau. Coulomb stress transfer modelling demonstrated that the earthquake significantly modified the regional stress field. [8] reported peak static Coulomb stress increases of approximately 1.3 bar in areas surrounding the rupture zone, suggesting an enhanced likelihood of future fault reactivation. Stress accumulation was particularly concentrated in the southern and up-dip portions of the source fault. Similarly, [12] identified positive coseismic stress perturbations at depths of approximately 10 km beneath the southern part of the rupture area, indicating that portions of adjacent fault systems may have been advanced toward failure. Such stress redistributions are considered important mechanisms controlling the spatial migration of seismicity and the occurrence of subsequent moderate earthquakes.

Following the Mirpur sequence, the Mw 5.0 Kharian 2024 earthquake represents the second-largest instrumentally recorded event in the area after the 2019 Mirpur earthquake. Despite its large magnitude and shallow depth (3 km), the Kharian earthquake caused no reportable damages.

On 26 May 2026, the Mw 4.5 Jalalpur Sharif earthquake occurred approximately 60 km southwest of the Mirpur epicentral area and about 40 km from the Kharian earthquake source region. Although moderate in magnitude, the earthquake caused unexpectedly severe damage to residential structures, resulting in one fatality and fourteen injuries. Field observations revealed widespread cracking of masonry buildings and infrastructure damage within the epicentral zone. Residents reported strong north–south ground motion during the event, while several damaged structures exhibited deformation patterns consistent with a dominant N–S component of shaking. The occurrence of significant damage from a relatively moderate earthquake raises important questions regarding its source characteristics, focal depth, rupture geometry, local site conditions, and tectonic setting.

Despite the significant damage caused by Jalalpur Sharif earthquake, its causative fault, rupture geometry, focal depth, and tectonic significance remained poorly constrained. The epicentral region is located on the footwall of the Salt Range Thrust (SRT), where no surface-mapped active fault has previously been identified, raising important questions regarding the existence of concealed or blind seismogenic structures beneath the northwestern Himalayan foreland. Determining whether the earthquake originated on a buried thrust associated with the Pabbi Anticline system, a subsidiary structure linked to the SRT, or another previously unrecognized fault is essential for understanding the distribution of active deformation and assessing future seismic hazard in the region. Moreover, the occurrence of this event within an area affected by stress perturbations following the 2019 Mw 5.8 Mirpur earthquake provides an opportunity to evaluate the role of stress transfer and fault interaction in controlling contemporary seismicity in northeastern Pakistan.

In this study, we integrate detailed field observations, gravity data modelling, and local waveform moment tensor inversion of broadband seismic recordings to determine the source characteristics, focal depth, faulting mechanism, and tectonic setting of the 2026 Jalalpur Sharif earthquake. The combined geophysical and geological analyses are used to identify the most likely causative structure, evaluate its relationship with regional tectonic elements, and investigate the factors responsible for the unexpectedly severe damage produced by a moderate-magnitude event. The results provide new constraints on active faulting beneath the Himalayan foreland fold-and-thrust belt and contribute to a more robust assessment of seismic hazard in the Jalalpur Sharif region and adjacent parts of northeastern Pakistan.

2. Geology and Tectonics

The Jalalpur Sharif region is located along the eastern Salt Range at the northwestern Himalayan deformation front, where active shortening associated with the ongoing India–Eurasia collision is transferred into the foreland [10,18]. This is a part of the Himalayan tectonic bend, which links the predominantly compressive deformation central Himalaya and transpressional deformation of western Himalaya. Oblique convergence, at an average rate of ~5 mm yr⁻¹, is accommodated through a combination of southward-directed thrusting and strike-slip faulting, producing a complex partitioned deformation field [3,4,19,20,21,22,23].

Within this tectonic framework, the Salt Range and Potwar Plateau constitute the frontal part of the Himalayan fold-and-thrust belt. They form a large allochthonous thrust sheet translated above a regional evaporite-rich décollement developed near the Precambrian basement, giving rise to a classic thin-skinned fold-and-thrust system characterized by fault-propagation folds, duplexes, and imbricate thrusts [24,25,26]. Eastward, the Salt Range frontal thrust gradually loses surface expression, becomes blind, and continues into the Chambal Ridge, Rohtas Anticline, and Pabbi Hills across the Jhelum River [27,28].

The earthquake epicentral area lies immediately south of the eastern Salt Range, where deformation is expressed by the Diljabba Ridge and the Chambal–Tilla Jogian Ridge. These NE–SW-trending structures define the dominant structures of the eastern Salt Range and contrast with the E–W-oriented folds farther west. The Chambal–Tilla Jogian Ridge consists of steep monoclines disrupted by thrust and tear faults, whereas the Diljabba Ridge forms a steep anticline dissected by the Diljabba–Domeli Thrust. Except for the Domeli Thrust, most mapped faults exhibit only limited surface displacement, suggesting that a significant component of shortening is accommodated by blind structures at depth [29].

South of the Salt Range, the Pabbi Anticline forms the principal active structure in the Jalalpur Sharif area. It is taken as a fault-propagation fold developed above a blind thrust that merges downward into the regional décollement [30]. Geological and geophysical evidence indicates that this structure has remained active throughout the late Quaternary, controlling regional drainage development, including the course of the Jhelum River [29,31]. Recent seismicity, including the December 2024 Mw 5.0 event, and the 2026 Mw 4.5 Jalalpur Sharif earthquake, depict the active deformation within this blind thrust system. The concentration of these moderate earthquakes highlights the role of the Pabbi Anticline and adjacent blind thrusts in accommodating active shortening and emphasizes their significance for seismic hazard assessment in the northwestern Himalayan foreland.

3. Data and Method

3.1. Seismic Data Compilation

Waveform data from local seismic from the Centre for Earthquake Studies (CES) and the Pakistan Meteorological Department (PMD) were utilized to carry out moment tensor inversion of the 2026 Jalalpur Sharif earthquake and to assess its seismotectonic significance. A total of 49 seismic stations form the joint network, including 33 stations operated by CES and 16 by PMD, providing coverage across different areas of Pakistan (Figure 2). The seismic stations have been operational since 1976, continuously transmitting recorded data to the central processing center in Islamabad through radio and satellite communication systems. These stations are broadband instrument and providing continuous recording, enabling reliable and high-quality acquisition of seismic waveform data [see 8,32,33 for details].

Earthquake locations and source parameters (origin time, depth, and epicenter) were calculated using the HYPOCENTER algorithm available in the SEISAN processing environment [34,35,36,37]. Earthquake solutions with RMS residuals <0.3 s were taken as reliable located events [36]. The CES catalog provides earthquake solutions with average location uncertainties of ~8 km and local magnitude (ML) uncertainties of ~0.2 units [38,39,40].

3.2. Waveform Inversion

Waveform Waveform inversion was carried out for the Jalalpur Sharif earthquake (Mw 4.5) to estimate the focal mechanism solution. To obtain reliable fault plane solutions and focal depth estimates, stations having high noise level, timing inaccuracies, or amplitude calibration problems were excluded from the analysis. Waveform data were processed using Seismic Analysis Code (SAC). A band-pass filter with a frequency range of 0.07–0.1 Hz was applied to reduce the influence of shallow subsurface effects on the source signals [41,42,43,44]. Instrument response correction was applied to the waveform data, with mean and trend removal performed before further analysis. The generation of synthetic seismograms requires the computation of Green’s functions at various source depths and station locations, which are controlled by the crustal velocity model and wave propagation behavior. A Green’s function was computed by using the discrete wave number technique of [45]. The accuracy of fault-plane solutions depends strongly on the assumed subsurface velocity structure and the presence of near-surface anisotropic effects [46,47,48] For Green’s function computation, we employed the local crustal velocity model developed by [49]. Their velocity model was developed using observations from the same seismic network utilized in this study. This model has subsequently been adopted in several recent investigations for estimating earthquake source parameters [32], while other studies have highlighted its limitations [47,48].

To estimate the source parameters of the recent earthquake, the moment tensor inversion approach of [50] was applied. The earthquake source mechanism was represented by six independent components of the seismic moment tensor. The optimal source parameters, including strike, dip, rake, and focal depth, were selected on the basis of lowest variance reduction value. It evaluate observed and synthetic waveforms fitting, where the variance reduction strongly effected by both amplitude and time. Time corrections were applied to the waveforms to improve cross-correlation and achieve better variance reduction ($VR=/Syntheti{c}^2/Dat{a}^2/$) value. All seismograms were treated with equal weighting during the inversion. The best-fit source solution, characterized by the lowest Vr value, and the comparison between observed and synthetic waveforms for the Jalalpur Sharif event are illustrated in Figure 2 and Figure 3.

The stability of the inversion results was evaluated using the condition number (CN), which is determined from the ratio of the maximum to minimum eigenvalues of the Green’s function matrix [51]:

$$CN=\sqrt{{\displaystyle \frac{e_{max}}{e_{min}}}}$$

where $e_{max}$ and $e_{min}$ represent the maximum and minimum eigenvalues, respectively. A lower CN value show a well-conditioned inversion [52].

In addition to this event, four events with Mw ≥ 4.9 available from Global and published literature [7] are also shown in Table 1 and Figure 2.

3.3. Seismicity Data Analysis

Seismicity recorded between 2010 and 2025 was investigated to evaluate the temporal evolution of earthquake activity in the study area. The analysis was based on a unified earthquake catalog developed by integrating datasets from CES and PMD, which provides a lower magnitude detection threshold than most regional and global catalogs. Data processing and catalog preparation followed procedures similar to those described by [53] and [8]. The spatial pattern of earthquake occurrence within the study region is shown in Figure 2.

The magnitude of completeness (Mc) was determined using the maximum curvature method of [54], which is commonly employed to evaluate the completeness level of earthquake catalogs. The Mc represents the lowest magnitude above which the recorded seismicity is considered reliably and consistently detected. The frequency–magnitude distribution (FMD) for the study area, together with the estimated Mc value, is presented in Figure 4(a).

The Gutenberg–Richter (G–R) relationship was used to examine the statistical distribution of earthquake magnitudes within the study area over a specified period. This well-established seismicity model demonstrates that the frequency of earthquake occurrence. Because of its broad applicability in seismic hazard and seismotectonic studies, the G–R relationship remains a fundamental tool for quantifying earthquake activity. The frequency–magnitude distribution (FMD) is given by:

$$N\left(M\right)={10}^{a\text{-}bM}$$

where, N(M) is the cumulative number of earthquakes with magnitudes (M ≥ Mc). The a-value is the seismic productivity, while the b-value reflects the relative occurrence of small versus large earthquakes [54,55].

The b-value often exhibits substantial fluctuations over short observation periods, typically ranging from 0.5 to 2.5, whereas it commonly approaches 1.0 when calculated over longer time intervals [56]. Variations in the frequency–magnitude distribution have been linked to differences in rock properties, deformation rates, tectonic setting, focal depth, and stress conditions, although the exact controlling mechanisms remain uncertain [54,57,58,59].

The temporal evolution of seismicity in the study area is shown through the daily earthquake rate and cumulative number of events in Figure 4(b) and Figure 4(c), respectively. These analyses provide valuable information on changes in seismic activity through time and help identify possible earthquake-triggering processes. They also assist in evaluating whether seismic activity in one area may influence neighboring regions through stress transfer and fault interactions, thereby contributing to clustered or sequential earthquake occurrence.

3.4. Seismogenic Depth

The seismogenic zone is identified by a noticeable decrease in earthquake occurrence with increasing depth, typically between 10 and 20 km [60,61,62]. The thickness of this active seismic layer is a critical factor that influences fault rupture dimensions and constrains the maximum magnitude of earthquakes that a fault can generate [63,64]. In addition, the depth to the basement is an important geological parameter, as it affects the accumulation and release of tectonic stress and therefore plays a significant role in the generation of large earthquakes [65,66].

Seismicity in the Mirpur–Jalalpur Sharif region was examined to estimate the thickness of the seismogenic layer. A total of 152 earthquakes that occurred between 2010 and 2025 within a 70 km radius of the mainshock were selected for relocation. Only events recorded by at least six seismic stations were included to ensure reliable hypocentral solutions. Precise determination of earthquake focal depths depends on the selection of seismic velocity model, as the adopted model directly affects event locations and helps minimize uncertainties in depth estimates [67]. Seven velocity models were considered in this study (Appendix A, Figure A1), including models developed for Pakistan and neighboring regions of India. Among these, three models were specifically established for Pakistan and are referred to as Soomro [49], Qaisar [68], and WinPak [69]. Four velocity models from India were also incorporated, including those labeled M01, M02, and M12 [70]. Notably, the velocity model of Soomro et al. was the only local-scale model constrained using the same seismic network employed in this study. In contrast, the other velocity models were developed for broader regional applications and therefore may not adequately capture local crustal heterogeneities within the Mirpur–Jalalpur Sharif region [49,68,69]. In addition, a one-dimensional seismic velocity model for the upper and central Indus Basin was developed using data from 486 local earthquakes. To identify the most appropriate velocity structure for the study area, seven candidate models were evaluated, and the model yielding the lowest RMS travel-time residuals was chosen (Appendix Figure A1). Earthquake depths were then determined using a grid-search procedure in which the epicentral coordinates of each event were held constant while the source depth was systematically varied. The depth associated with the minimum RMS residual was taken as the preferred focal depth for that event (Figure 5).

3.5. Gravity Data

Gravity analysis was done from the TOPEX (https://topex.ucsd.edu/cgibin/-get_data.cgi). Bouguer and Terrain corrections, were applied to achieve the complete Bouguer anomaly [33,71]. The complete Bouguer anomaly (CBA) provides is the combination of near surface, intermediate and deep responses. As the Jhelum event (May 26, 2026) was occurred at shallow depth i.e. 3km, so we studied the structural variation in shallow depth in locality of said event and its surrounding as well as along the Kharian Earthquake that was occurred in near past December 5, 2024. For this, the shallow, intermediate and regional gravity responses (less the 2km, 2 to 3km and more the 3km, respectively) were separated from CBA using the technique of radial average power spectrum (RAPS). This technique is commonly used for assessing gravity responses at various depths [72,73,74,75]. To improve the resolution of features, the data was also subjected to upward continuation [76].

4. Results and Discussion

The Mw 4.5 Jalalpur Sharif earthquake of 26 May 2026 offers valuable insight into the active deformation processes and seismogenic structures of the Jhelum region in northeastern Pakistan. The earthquake occurred at 19:05:50 PST (14:05:50 UTC) near Jalalpur Sharif and caused considerable damage to residential buildings in the epicentral area. The event resulted in one fatality and several injuries. Despite its moderate magnitude, the earthquake produced unexpectedly strong local impacts, underscoring the vulnerability of existing infrastructure and emphasizing the seismic risk associated with active, yet insufficiently understood, tectonic structures in the region.

The earthquake epicenter is located within the footwall of the Salt Range Thrust (SRT), where no surface fault has been mapped in the available geological literature (Figure 1). This observation raises important questions regarding the subsurface structures responsible for the earthquake and their relationship to the regional tectonic framework.

To constrain the faulting mechanism and identify the causative structure, a moment tensor inversion was conducted using local seismic waveform data. Seismograms recorded by the Centre for Earthquake Studies (CES) and the Pakistan Meteorological Department (PMD) seismic networks were employed in the analysis (Figure 2). To further validate the inferred source mechanism and investigate the underlying subsurface structure, gravity data modeling was also performed. The combined interpretation of seismic and gravity datasets provides valuable insights into the active tectonics and seismogenic architecture of the Jalalpur Sharif region.

4.1. Faulting Style and Tectonic Association

The local seismic stations used for the moment tensor inversion of the 26 May 2026 Jalalpur Sharif earthquake are shown in Figure 2. Source parameters were determined through waveform inversion, and the preferred solution was selected based on the highest fitting between observed and synthetic waveforms, corresponding to a variance reduction (Vr) of approximately 35% (Figure 3). A grid-search procedure was applied to identify the optimum focal depth, yielding a preferred depth of about 3 km. The robustness of the inversion was assessed using the condition number (CN), which is commonly employed to evaluate the stability and reliability of moment tensor solutions. The obtained CN value of ~3.7 (Table 1) lies within the acceptable range suggested by [51], indicating that the derived source parameters are well constrained and reliable.

Figure 3. Comparison of observed (solid lines) and synthetic (dotted lines) waveforms for the 2026 Jalalpur Sharif mainshock. The seismic station codes, maximum amplitudes, and waveform components used in the inversion are indicated above each trace. The derived focal mechanism solution is displayed as a beach ball. A grid-search approach was employed to estimate the focal depth, and the corresponding variance reduction values for different trial depths are shown in the upper-right panel. The preferred depth, corresponding to the minimum variance reduction value, is marked by a vertical dotted line.

Figure 3. Comparison of observed (solid lines) and synthetic (dotted lines) waveforms for the 2026 Jalalpur Sharif mainshock. The seismic station codes, maximum amplitudes, and waveform components used in the inversion are indicated above each trace. The derived focal mechanism solution is displayed as a beach ball. A grid-search approach was employed to estimate the focal depth, and the corresponding variance reduction values for different trial depths are shown in the upper-right panel. The preferred depth, corresponding to the minimum variance reduction value, is marked by a vertical dotted line.

The preferred focal mechanism indicates predominantly thrust faulting with a minor left-lateral strike-slip component on a northeast–southwest (NE–SW) striking fault plane. This oblique-slip mechanism is consistent with the regional compressional tectonic regime of the northwestern Himalayan foreland and the Potwar Plateau, where ongoing convergence between the Indian and Eurasian plates is accommodated through a combination of thrusting and strike-slip deformation. Similar fault kinematics were recently documented by [7,28], who identified active thrust-related deformation within the Pabbi Anticline and reported subsidiary left-lateral strike-slip faults exhibiting orientations similar to that of the Jhelum Fault.

From a geological perspective, this depth corresponds closely to the estimated thickness of the sedimentary succession underlying the Pabbi Anticline. Geological and geophysical studies indicate that the folded sedimentary sequence in this area reaches nearly 3 km in thickness before encountering the basement [30]. The correspondence between the earthquake depth and the sedimentary cover thickness suggests that rupture likely occurred near the basal detachment or within thrust structures associated with the fault-propagation fold system responsible for the growth of the Pabbi Anticline.

Additional support for this interpretation is provided by the 2024 Kharian earthquake (having depth of 3 km, [7]), located approximately 40 km east of the Jalalpur Sharif epicenter. That event was also interpreted as being related to active deformation within the Pabbi Anticline fault-propagation fold system. These observations indicate that the Pabbi Anticline and its associated blind thrust faults remain tectonically active and continue to accommodate crustal shortening within the eastern Potwar Plateau–Salt Range fold-and-thrust belt. The occurrence of two shallow thrust-dominated earthquakes within a short time span further highlights the seismogenic potential of these concealed structures and their role in ongoing deformation of the region.

4.2. Seismogenic Depth

To select an appropriate velocity structure for earthquake relocation in the Jhelum region, seven one-dimensional velocity models were tested, including three models developed for Pakistan and four from neighboring regions of northern India. Among the evaluated models, the local velocity model of [49], which was derived using recordings from the same seismic network, yielded the smallest travel-time residuals (~ 0.3 s) between observed and synthetic data (Figure 4b).

The relocated seismicity exhibits concentration of earthquakes at depths of approximately 10–15 km, with a peak near 12 km (Figure 4). This depth interval represents the principal seismogenic layer beneath the Jhelum region and corresponds closely to the inferred position of the Main Himalayan Thrust (MHT), the regional basal décollement. It may suggests that a significant portion of crustal shortening and strain accumulation is accommodated along the MHT or within associated thrust structures rooted in this detachment. The concentration of earthquakes at these depths further indicates that the MHT and its associated structures play a fundamental role in controlling the distribution of seismic deformation within the region.

In contrast, the 2026 Jalalpur Sharif earthquake occurred at a much shallower depth of about 3 km. This depth corresponds closely to the estimated thickness of the sedimentary succession forming the Pabbi Anticline and indicates that the earthquake was not generated directly on the deeper MHT. Instead, the event likely originated on a shallow blind thrust or fault-propagation structure within the folded sedimentary cover. The thrust-dominated focal mechanism, together with the shallow hypocentral depth, supports the interpretation that the earthquake was associated with active deformation of the Pabbi Anticline, where shortening is transferred from the regional décollement to shallower thrust splays and fold-related faults.

The relationship between the shallow Jalalpur Sharif earthquake and the deeper concentration of regional seismicity suggests a mechanically linked fault system. While the MHT accommodates regional-scale convergence at depths of around 10-15 km, deformation is locally partitioned upward through subsidiary thrust faults that propagate into the sedimentary sequence. These shallow structures are capable of generating damaging earthquakes despite their relatively small magnitudes, as demonstrated by the Jalalpur Sharif event, which caused significant damage in the epicentral area.

A similar pattern has been observed in the 2019 Mirpur earthquake (Mw 5.8) nucleated at a depth of approximately 5 km and was associated with deformation above the Main Frontal Thrust (MFT). Subsequent studies showed that many aftershocks occurred on a steeper splay fault reaching depths of nearly 15 km, linking shallow faulting to deeper seismogenic structures. Likewise, the 2024 Kharian earthquake, located east of the study area, occurred at a shallow depth.

Small number of earthquakes occur below 17 km depth. This observation is consistent with previous studies of the northwestern Himalayan foreland, which indicate that active deformation is largely confined to the shallow and intermediate crust [27,77,78]. The decrease in seismicity with depth likely reflects increasing confining pressure and progressively stronger crustal conditions, which reduce the occurrence of brittle failure. Consequently, the 10–15 km depth interval represents the most favorable zone for earthquake nucleation and stress release, while shallow earthquakes such as the 2026 Jalalpur Sharif event likely occur where deformation is transferred upward from the regional décollement onto active thrust splays and fault-propagation folds within the sedimentary cover.

4.3. Regional Seismicity Characteristics

For completeness and reliability of the seismic catalog, the magnitude of completeness (Mc) was estimated as 1.3 (Figure 5a). Only events with magnitudes equal to or greater than Mc were subsequently used for seismicity analysis. The resulting Gutenberg–Richter relationship yields a b-value of 0.68 ± 0.03, indicating a relatively lower b-value for typical crustal regions. The observed low b-value may partly reflect the influence of the 2019 Mirpur earthquake aftershock sequence, which contributes a higher proportion of moderate-magnitude events to the catalog. It may also indicate heterogeneous stress conditions and localized stress accumulation within the Jhelum–Mirpur region [8].

A substantial change in the transient seismicity rate was observed following the 2019 Mirpur earthquake. The mean daily seismicity rate increased from approximately 0.03 events/day prior to the mainshock to 0.11 events/day afterward (Figure 5b), consistent with observations reported by [8] for the Mirpur region. Comparison of cumulative earthquake occurrence north and south of 33°N latitude reveals contrasting temporal behavior (Figure 5c). While the northern zone was dominated by the Mirpur aftershock sequence, the southern Kharian–Jalalpur Sharif region remained relatively quiescent during the aftershock triggering period. [8] reported an aftershock duration of approximately 600 days for the Mirpur sequence, after which a noticeable increase in seismic activity emerged in the southern part of the study area beginning in 2022. The occurrence of both the 2024 Kharian earthquake and the 2026 Jalalpur Sharif earthquake during this period of accelerating seismicity suggests progressive stress accumulation and renewed activation of fault structures within the southern Jhelum region.

4.4. Coulomb Stress Changes

The potential contribution of stress transfer to the 2026 Jalalpur Sharif earthquake was investigated using Coulomb stress modeling. The model of [8] was revised by including the 2019 Mirpur and 2024 Kharian earthquakes as source events. The Jalalpur Sharif fault plane was taken as the receiver fault. The resulting stress field was analyzed to evaluate whether stress changes from earlier earthquakes increased the likelihood of fault rupture in the epicentral area. The modeling results indicate that the epicentral area is located within a region of positive Coulomb stress change, implying that the preceding earthquakes increased the likelihood of fault reactivation in the area. Although the calculated stress increase is modest, with a maximum value of approximately 0.001 bar, it suggests that static stress perturbations may have contributed to advancing the fault toward failure. The resulting stress distribution is presented in Figure 6.

Positive Coulomb stress changes are concentrated over the Pabbi Anticline, supporting the interpretation that this fold-thrust structure remains tectonically active. Both the 2024 Kharian and 2026 Jalalpur Sharif earthquakes occurred within this stress-enhanced zone and are spatially associated with the Pabbi Anticline. The positive stress anomalies suggest that these faults are favorably oriented for failure under the current stress regime. Furthermore, stress transfer from the 2019 Mirpur earthquake sequence may have advanced the failure clock of nearby faults, thereby increasing the likelihood of subsequent earthquakes in the region. The occurrence of multiple earthquakes within the same stress corridor indicates ongoing deformation and stress redistribution among interconnected thrust faults. These observations suggest that the Pabbi Anticline and its associated blind thrusts constitute active seismogenic structures and represent an important source of seismic hazard in the Jhelum region.

4.5. Gravity Modeling

Gravity data investigation directed to discriminate variations in gravity in the region, discern structural variations/ faulting pattern and the impact of tectonic features. Figure 1 pageants the CBA map of study region, which represents the collective gravity response of shallow, intermediate and deep structures. The map highlights the higher gravity values on the south-western side, compared to rest of region. Salt Range Thrust (SRT), the regional tectonic feature is clearly identifiable CBA response, as shown in Figure 7. Moreover, minor indications of NE-SW trending fold (Pabbi anticline) just south of the Kharian earthquake event are also observable (sandwiched between the northern and southern side high density parallel regions). Figure 8 represents the shallow gravity response (less the 2km) separated from CBA for our area of interest. The recent Jhelum event (May 26, 2026) can be seen as the continuation of same structure, with many localized left lateral movements. In left side adjacent to recent event, the left lateral movements are also observable, clearly. In Figure 9, the continuity of structure becomes clear, as we move to toward the intermediate response. The same continuity becomes vanish in regional response below 3km, separating south western high density region from other areas.

4.6. Field Observations and Macroseismic Intensity Assessment

The recent moderate-magnitude earthquake caused anomalous damage within a localized area, where a teenager was killed and at least a dozen people were injured due to the collapse of houses. A field survey was conducted using questionnaires designed to collect the information required for intensity assessment according to the Modified Mercalli Intensity (MMI) scale. Earthquake-induced environmental effects, including rockfalls, landslides, and liquefaction, were also identified during the field investigation. Details of these observations are provided in the following subsections.

4.6.1. Field Survey of the Epicenteral Area

According to the designed questionnaire, more than eighty individuals were interviewed at fifteen localities covering the epicentral area of Jalalpur Sharif and surrounding villages, including Nathwala, Mariala, Dhariala Jalip, Pir Chack, Jhandran, Chandh, and Wagh. Detailed field observations, together with photographic documentation of structural damage and earthquake-induced environmental effects, were conducted during the survey (Appendix B).

Based on these observations, the highest intensity was recorded at Jalalpur Sharif, where the greatest loss of life and property occurred. The epicenter determined from the local CES seismic network closely corresponds to the area of maximum observed intensity, providing confidence in the earthquake location. Residents in the epicentral area also reported hearing a roaring sound during the earthquake, suggesting rupture of a very shallow asperity capable of generating audible seismic waves (>20 Hz). The zone of maximum damage covered approximately 4.5 km², and representative photographs of the damage are presented in Photos 1–6 (Appendix B).

The most severe damage occurred in poorly constructed buildings. Typical damage patterns included wall cracking, splitting of masonry units, partial wall collapse, and roof failure. Several reinforced concrete (RC) structures also exhibited cracks in roof slabs and beam–column joints, indicating inadequate seismic detailing and poor construction practices (Photo 6). In addition, utility poles were observed to have tilted northward (Photos 4 and 7), while in several buildings the walls had separated from the roof and were displaced toward the north. Similar observations were reported by local residents during interviews. These features collectively indicate a dominant north–south component of ground motion during the earthquake. Macroseismic evaluation indicates a maximum intensity of VII on the MMI/EMS-98 scale within the epicentral area (Figure 10).

The spatial distribution of intensity reveals a preferential elongation in the NE–SW and E–W directions, broadly corresponding to the strike of the causative structure and the trend of the Pabbi Anticline. This pattern suggests that the propagation of seismic energy and the distribution of damage were influenced by the underlying tectonic framework. Away from the epicentral region, shaking intensity decreased progressively in all directions, except at a few locations where structural damage resulted primarily from secondary effects rather than direct ground shaking (Photos 10–15).

No damage was observed in the well-engineered structures at Head Rasul (Photo 16), although the earthquake was felt by most residents. Based on field observations and questionnaire responses, an intensity of II on the MMI scale was assigned to the area. A post-earthquake photograph of Head Rasul is shwon in Photo 16.

4.6.2. Earthquake Environmental Effects (EEEs)

During field survey, Earthquake Environmental Effects including Liquefaction, Turbidity of groundwater and Rock-fall / Land-sliding were investigated in detail. Shaking related liquefaction could be observed in the form of floor settlement, tilting of electric poles and turbidity of groundwater.

4.6.2.1. Turbidity of Groundwater

Shaking related turbidity of groundwater was only reported from a limited area (i.e. Jalapur Sharif) lasting for a few hours after occurrence of earthquake.

4.6.2.2. Liquefaction Effects on Civil Structures

The area dominantly consists of fluvial sand and silt deposits susceptible to liquefaction when subjected to shaking especially in horizontal direction. Tilting of civil structures and poles (particularly with shallow foundations) was observed not only in the epicentral area but also at considerable distances. For example, appearance of wide cracks in the piers / abutments of road bridge and a mosque more than twelve kilometers away signifies the extent of such damage due to differential settlement caused by sand liquefaction and site amplification factors. Pictorial evidences of these damages can be viewed in Appendix-B (Photo 8 -11).

4.6.2.3. Dust Caused by Rock-Fall and Landslides

The most striking feature of this seismic event was dust caused by rock-fall / landslides along both limbs of the ridge north of epicenter. This was observed by residents of epicenter as well as Chamkon Valley (Chamkon: acronym of the names of villages situated within the valley). The dust rose to such a height that the residents of the farthest villages in the said valley could observe it clearly. This is another fact indicating shallow occurrence of earthquake that caused severe shaking of the ridge resulting in rock-fall / landslides. Photography of the area is restricted due to presence of strategic formation in the area; however, limited pictures beyond the restricted area have been taken to show the nature and magnitude of mass movement causing the dust. Pictorial evidences of Landslide / Rock-fall can be viewed in Appendix-B (Photo 8 and Photo 9).

5. Conclusion

The Mw 4.5 Jalalpur Sharif earthquake of 26 May 2026 caused significant localized damage, resulting in one fatality, fourteen injuries, and a maximum intensity of VII on the Modified Mercalli Intensity (MMI) scale in the epicentral area. Field investigations documented several earthquake-induced environmental effects, including liquefaction, temporary groundwater turbidity, differential settlement, tilting of utility poles, and landslides within the Quaternary deposits of the Tilla Jogian Range. Moment tensor inversion, supported by gravity modelling, indicates that the earthquake originated at a shallow depth of approximately 3 km and was associated with a blind thrust beneath the Pabbi Anticline. The source mechanism is characterized by predominantly thrust faulting with a minor left-lateral strike-slip component. The spatial distribution of macroseismic intensity was elongated along the strike of the inferred causative structure, while observed north–south ground displacement, evidenced by tilted utility poles and structural deformation, is consistent with the minor strike-slip component of the focal mechanism. Seismicity patterns and Coulomb stress modelling suggest that the Jalalpur Sharif source region lies within a stress-enhanced zone influenced by the 2019 Mw 5.8 Mirpur earthquake. The occurrence of both the 2024 Mw 5.0 Kharian and 2026 Jalalpur Sharif earthquakes during a period of elevated seismicity indicates ongoing stress redistribution and progressive strain accumulation within the region. These findings suggest an increasing seismic hazard in the Jhelum–Kharian–Jalalpur Sharif corridor and highlight the important role of concealed thrust structures in accommodating active deformation within the northwestern Himalayan foreland.