Assessment of Environmental Impacts at the Babawa Quarry, Kano State, Nigeria, Using Integrated Geoelectrical Methods

Geophysical techniques involve the measurement of magnetism, gravity, acoustic or elastic waves, radioactivity, heat flow, electricity, and electromagnetism. These measurements are mostly carried out onshore or offshore, although some are obtained from aircraft, satellites, boreholes, mines, and even at ocean depths [1]. Such techniques are useful for investigating subsurface structures and material properties without requiring direct excavation. Electrical resistivity surveying is one of the most widely applied geophysical methods. It is commonly used for mapping rocks of different porosities, especially in hydrogeological studies for aquifer delineation and contamination detection, as well as for mineral exploration [2]. Recent studies have shown that integrating resistivity and induced polarization methods is effective for characterizing fractured and weathered basement terrains and defining subsurface lithological contrasts [3], [4], [5].

Quarrying is a land-use practice that involves the extraction of non-fuel and non-metallic minerals such as sand, gravel, and limestone for construction purposes. Langer [6] described quarrying as the process of exploring and exploiting stone from rocks through open excavation. However, quarrying activities, particularly rock blasting and crushing, are known to generate several occupational and environmental hazards, including air, noise, water pollution, soil degradation, and health effects among nearby residents [7], [8], [9], [10]. Previous studies have reported that quarrying and mining operations can significantly affect the environment through noise and air pollution, biodiversity loss, alteration of geochemical cycles, ecological imbalance, and habitat destruction. Fractures and joints are planes of weakness formed where stress has caused partial loss of cohesion in rocks, and these discontinuities strongly influence mechanical behavior and groundwater pathways in crystalline terrains [11], [12]. Such weak zones control fracture network architecture and fluid movement, affecting subsurface permeability and deformation responses [13], [14].

The Babawa main quarry site, located in the Gezawa Local Government Area of Kano State, is an area of active quarrying and frequent rock blasting due to the availability of subsurface rock materials. Ground vibration occurs persistently in the area and poses environmental and structural challenges, as observed from cracks in the overburden and nearby structures. Despite these challenges, there is limited integrated geophysical information on the subsurface response to blasting activities in the area. Therefore, this study applies electrical resistivity, induced polarization, and spontaneous potential methods to investigate subsurface conditions and identify weak and fractured zones associated with rock blasting. The findings are expected to provide baseline geophysical data that will support government planning, environmental management, and the sustainable utilization of quarry resources in the Babawa area.

The study area is situated in Babawa, Gezawa Local Government Area, Kano State. The area lies within the Northern Nigerian Basement Complex region between longitudes 12.013369°N and 12.015819°N and latitudes 8.590726°E and 8.600092°E, as shown in Figure 1.

The purpose of electrical surveys is to determine the subsurface resistivity distribution by making measurements on the ground surface. From these measurements, the true resistivity of the subsurface can be estimated. The ground resistivity is related to various geological parameters such as the mineral and fluid content, porosity and degree of water saturation in the rock. The fundamental physical law used in resistivity surveys is Ohm’s law that governs the flow of current in the ground [15]. The law is given as:

where, $E$ denotes the electric field intensity, $\rho$ is the resistivity of the medium, and $J$ denotes the current density.

By adopting Ohm’s law to account for the conditions specific to the electrical resistivity imaging surveys, the basic equation of apparent resistivity [16] is given as:

Spontaneous potential is the naturally occurring electrical potential of the earth resulting from geological, geochemical, and hydrological interactions which cause electric potentials to exist in the earth in the vicinity of the measurement point. Since 1830, the spontaneous potential method has been employed in the search for minerals. The spontaneous potential method, as its name implies, is based upon measuring the natural potential differences which generally exist between any two points on the ground. These potentials, partly constant and partly fluctuating, are associated with electric currents in the ground. The constant and unidirectional potentials are set up due to electrochemical actions in the surface rocks or in bodies embedded in them, ranging normally from a fraction of a millivolt to a few tens of millivolts.

Chemical reactions which evolve as a result of the ore body being in contact with the solutions of varied composition give rise to different solution pressure contrasts which in turn generate an electromotive force which causes a flow of current in the ground [15]. The electrokinetic potential is given as:

where, $\varepsilon$ denotes the dielectric permittivity of the pore fluid, $E_k$ is the electrokinetic potential, $\rho$ is the electrical resistivity of the pore fluid, $C \varepsilon$ is the electrofiltration coupling coefficient, $\Delta P$ is the pressure difference, and $\eta$ is the dynamic viscosity of the pore fluid.

Induced polarization is an extension of the electrical resistivity method that exploits the ability of rocks and rock-forming minerals to temporarily store electrical charge. The ABEM Terrameter SAS 1000/4000 measures a time-domain parameter known as chargeability. The chargeability is defined as:

where, $V(t)$ is the decaying voltage, $t_{i+1}$ and $t_i$ represent the start and end times of the interval, respectively, and $V_0$ is the voltage measured before the current is terminated by the terrameter [17].

The geophysical survey in the study area was carried out by laying cables along preselected profile directions with electrodes placed on the ground surface. The multi-core cables were arranged along the profiles with take-out intervals of 10 m for Profiles 1–4 and 5 m for Profile 5 to achieve the imaging. As seen in Figure 2, metallic jumpers were used to connect the take-outs to the grounded electrodes. The cables were attached to the top panel of the Lund imaging device, which was connected via a cable to the ABEM Terrameter SAS 1000. A 100 W solar panel continuously charged the setup, which was powered by a 12 V battery.

The Lund Imaging System was chosen from the start-up menu after turning on the terrameter. A record file was made for the first profile with the electrode spacing set to 10 m after the preferred mode (spontaneous potential, resistivity, or induced polarization) was chosen from the Record Manager. The grounding electrodes were filled with saltwater to lessen the impact of inadequate ground contact. To guarantee the best possible data acquisition, the integrity of the cable connections was also routinely assessed. The current mode was set to automatic, and a current of 1000 mA was chosen. In order to collect data from deeper subsurface sections, the Wenner L array was selected as Protocol 1. The acquisition systems automatically verified electrode contact integrity and sequentially executed the predefined measurement protocol to ensure that current flow through each electrode was properly established. The systems took measurements automatically and recorded them in the terrameter. Chargeability measurements were the most time-consuming, and the terrameter took roughly 20 minutes to finish taking readings along each profile.

All measured data, including apparent resistivity, chargeability, and potential differences from the survey lines, were downloaded via cable from the ABEM Terrameter SAS 1000 to a computer equipped with RES2DINV and ABEM SAS4000 Utilities software. The original data files (in .s4K format) were converted into .DAT format using the SAS4000 Utilities to ensure compatibility with the inversion software. A total of 15 datasets were generated, comprising five datasets each for resistivity, induced polarization, and spontaneous potential. The resistivity and induced polarization data were processed using RES2DINV (Version 3.54.44), while the spontaneous potential data were processed using Surfer (Version 12).

The geophysical survey was conducted along the profiles in three different rock quarries, using electrode spacing of 10 m for Profiles 1–4 and 5 m for only Profile 5 to find out the effects of rock blasting in decomposition/disintegration of the rock quarry and the geological changes caused by the active blasting of dynamite in the research area. In this research, high and low resistivity values were identified along the three quarry sites. High resistivity values are interpreted to indicate the presence of relatively unaltered, fresh granitic basement rocks. In contrast, low resistivity values are associated with highly weathered materials, including clays and gravels. Table 1 and Table 2 show the generated resistivity and chargeability values, respectively. Table 3 shows the borehole log data from Dakata Kawaji [18].

The software RES2DINV was utilized to generate three cross-sections for each profile namely, the measured section, the calculated section and the inverse model section of both resistivity and chargeability. Golden Surfer software was used to obtain the spontaneous potential contour map of the location. The vertical axis of the section represents the depths of the investigation and the horizontal axis represents the distance along the profiles. The measured resistivity section was formed by interpolating the raw/field data in two dimensions. The calculated resistivity section displayed the smoothed version of the measured resistivity section. The inverse resistivity and chargeability section was generated during modeling to produce the model section. These inverse model sections for each profile were interpreted in terms of geology by comparing the obtained resistivity and chargeability values with those in Table 1 and Table 2. The spontaneous potential contour obtained from the Surfer software was interpreted by considering the high and low potential values.

The cross-sections shown in Figure 3, Figure 4, and Figure 5 correspond to the resistivity, chargeability and spontaneous potential tomography results, respectively, for Profile 1. The profile was taken from the southwestern to the northeastern part of the quarry, starting from latitude 12.006169°N, longitude 8.605402°E to latitude 12.019215°N, longitude 8.602935°E, with a profile length of 600 m and an electrode spacing of 10 m. The RES2DINV inversion for this profile indicated a depth to the granitic basement complex of about 105 m. It revealed that the subsurface nature of the investigated area can be grouped into three layered structures. The top layer of low resistive nature extends to a depth of about 20 m at a distance of about 200 m to about 585 m along the profile, with resistivity ranging from 20 $\Omega \cdot$m to 200 $\Omega \cdot$m. By comparing the resistivity values with those in Table 1, the layer is found to be highly weathered basement rocks (gravels). Underlain by the middle layer extends to a depth of about 30 m at a distance of about 180 m to 520 m along the profile, with resistivity ranging from 200 $\Omega \cdot$m to 1000 $\Omega \cdot$m. By comparing the resistivity values with those in Table 1, the layer is found to be partially weathered basement complex rocks. The third layer has a resistivity value greater than 1000 $\Omega \cdot$m. By comparing the resistivity value with that in Table 1, the layer is found to be a fresh basement complex (granite). The highest resistivity value recorded along with this profile was 109264 $\Omega \cdot$m. The outcrop of fresh granite rock appeared on the surface at a distance of about 40 m to 180 m along the profile. The breakage appeared from about 160 m to 260 m along the profile due to the inability to position the electrodes because of rock outcrop in the region. The inverse resistivity model section and the corresponding geological interpretation showed that the top and middle layers are the affected regions, with low resistivity values less than 1000 $\Omega \cdot$m and the presence of fractures. These fractures which formed radially on the wall strata indicate the impact of rock blasting activities on the quarry site.

The chargeability generated for this profile (Figure 4) displays zones with weak rock (partially basement complex rock) and hard rock. By comparing the chargeability values obtained from the RES2DINV inversion with those in Table 2, the inverse chargeability model, as depicted by geological sections, showed the presence of weak rock zones/partially weathered basement complex (gravel) and hard rock zones/fresh basement complex rock (granite). The breakage appeared from about 160 m to 260 m along the profile due to the inability of electrode positioning caused by rock outcrops in the region. The weak rock zone formed as a result of active rock blasting in the quarry site.

The spontaneous potential contour map in Figure 5 shows the results of low and high spontaneous potential values. Low values suggest a region with no flow of fluid and highly intact and are found to be hard rock zones. High values indicate locations with the possibility of fluid flow and are found to be weak rock zones. Spontaneous potential values ranging from 0.32 mV to 0.52 mV were found to be high-potential zones (weak rock zones). At a position of about 180 m to 220 m and 330 m to 380 m from the ground surface of Profile 1, with a depth of about 20 m and 60 m, respectively, weak rock zones were delineated which suggest the affected regions due to the active rock blasting.

The cross-sections shown in Figure 6, Figure 7 and Figure 8 are resistivity, chargeability and spontaneous potential tomography results, respectively, for Profile 2. The profile was taken from the southwestern to southeastern part of the first quarry, starting from latitude 12.015836°N, longitude 8.611759°E and ending at latitude 12.006518°N, longitude 8.616237°E, with a profile length of 400 m. The RES2DINV inversion generated for this profile showed the depths of the granitic basement complex rock to be at 57.7 m. The subsurface nature of the investigated area can be grouped into three layered zones. The top layer of low resistive nature extends to a depth of about 12 m, with resistivity ranging from 20 $\Omega \cdot$m to 200 $\Omega \cdot$m. By comparing the resistivity values with those in Table 1, the layer is found to be a highly weathered basement complex (gravels). This is underlain by a middle layer that is uniformly distributed along the profile, with a thickness of approximately 48 m and resistivity ranging from 200 $\Omega \cdot$m to 1000 $\Omega \cdot$m. By comparing the resistivity values with those in Table 1, the layer is found to be partially weathered basement complex rock. The third layer has a resistivity value greater than 1000 $\Omega \cdot$m. By comparing the resistivity value with that in Table 1, the layer is found to be fresh basement complex (granite). The highest resistivity recorded along this profile was 2788 $\Omega \cdot$m. The overburden strata include some boulders and clay that appear on the surface of the quarry. This profile constitutes very thick overburden materials and a surface water channel due to some pockets of very low resistivity at the surface.

A surface water channel observed along the profile was discharged from a soap company located near the quarry site. The inverse model resistivity section showed that the top and middle layers are the affected regions, with low resistivity values less than 1000 $\Omega \cdot$m and the presence of fractures. These fractures formed radially on the wall strata, indicating the impact of rock blasting activities in the quarry site. Figure 7 showed the chargeability model for Profile 2. By comparing the chargeability values obtained from RES2DINV with those in Table 2, the image displays the locations of weak rock zones/partially basement complex rocks and hard rocks/fresh basement complex rocks. A hard rock has been observed at about a 360 m position along the profile. It suggests that the profile is highly affected by the rock blasting, as dominated by the weak rock zone.

The spontaneous potential contour map shows the results of low and high spontaneous potential values. Low values suggest a region with no flow of fluid and highly intact and are found to be hard rock zones. High values indicate locations with the possibility of fluid flow and are found to be weak rock zones. The spontaneous potential values that range from 0.28 mV to 0.48 mV are found to be high spontaneous potential zones (weak rock zones). At a position of about 180 m to 290 m along the profile and at a depth of about 50 m, a weak rock zone was delineated due to the active rock blasting.

The cross-sections shown in Figure 9, Figure 10, and Figure 11 are resistivity tomography, induced polarization and spontaneous potential, respectively, for Profile 3. The profile was taken from the north to south part of the first quarry, starting from latitude 12.007966°N, longitude 8.604948°E and ending at latitude 12.011103°N, longitude 8.611309°E, with a profile length of 400 m and an electrode spacing of 10 m. The RES2DINV inversion generated for this profile showed the depths of the granitic bedrock at 57.3 m and a surface distance of 400 m from the first electrode position. The subsurface nature of the investigated area can be grouped into three layered zones. The highly weathered basement complex/top layer of low resistive nature extends to a depth of about 30 m and a distance of 270 m to 360 m along the profile, with resistivity ranging from 50 $\Omega \cdot$m to 200 $\Omega \cdot$m. By comparing the resistivity values with those in Table 1, the layer is found to be gravel. This is underlain by a middle layer with a thickness of about 48 m and a distance from 180 m to 260 m along the profile, with resistivity values ranging from 200 $\Omega \cdot$m to 1000 $\Omega \cdot$m. By comparing the resistivity values with those in Table 1, the layer is found to be partially weathered bedrock. The third layer has a resistivity value greater than 1000 $\Omega \cdot$m and is found to be a fresh basement complex (granite). The highest resistivity value recorded along with this profile was 4471 $\Omega \cdot$m. The thick weathered strata outcrop has a depth from 39.6 m to 57.3 m. The very high resistivity arises from the intrusion of fresh basement granitic rock, formed from the surface of the profile to a depth of 57.3 m. The inverse model resistivity section and geological section showed that the top and middle layers are the affected regions, with low resistivity values less than 1000 $\Omega \cdot$m and the presence of fractures. These fractures formed radially on the wall strata, indicating the impact of rock blasting activities on the quarry site.

By comparing the chargeability values obtained from RES2DINV with Table 2, Figure 10 displays the locations of weak rock zones/partially basement complex rocks and hard rocks/fresh basement complex rocks. A hard rock has been observed at a position of about 250 m to 270 m along the profile. Spontaneous potential values that range from 0.27 mV to 0.45 mV were found to be high spontaneous potential zones (weak rock zones). At about a position from 330 m to 400 m with a depth of 50 m, a weak rock zone was delineated which occurred due to the active blasting of rock.

The cross-sections shown in Figure 12, Figure 13, and Figure 14 are resistivity tomography, induced polarization and spontaneous potential, respectively, for Profile 4. The profile was taken from northwestern to northeastern part of the second quarry, starting from latitude 12.006094°N, longitude 8.608914°E and ending at latitude 12.007821°N, longitude 8.610015°E, with a profile length of 400 m and an electrode spacing of 10 m. The RES2DINV inversion generated for this profile showed the depths to the granitic basement complex rock at 57.3 m. It revealed that the subsurface nature of the investigated area can be grouped into three layered zones. The top layer of resistive nature extends to a depth of about 10 m, with resistivity ranging from 20 $\Omega \cdot$m to 100 $\Omega \cdot$m. By comparing the resistivity values with those in Table 1, the layer is found to be a highly weathered basement complex (gravels). This is underlain by a middle layer that is uniformly distributed along the profile, with a thickness of about 25 m and resistivity values ranging from 200 $\Omega \cdot$m to 1000 $\Omega \cdot$m. By comparing the resistivity values with those in Table 1, the layer is found to be partially weathered basement complex rock. The third layer has a resistivity value greater than 1000 $\Omega \cdot$m and is found to be fresh basement complex rock (granite). The breakage appeared from about 105 m to 170 m along the profile, which resulted from the inability to position the electrodes due to the rock outcrop in the region. The highest resistivity recorded along with this profile was 48712 $\Omega \cdot$m. The RES2DINV showed thick weathered bedrock, as noticed by the presence of residual soil materials that were dark blue, pale blue and light green in color. The inverse model resistivity section and geological section showed that the top and middle layers are the affected regions, with low resistivity values less than 1000 $\Omega \cdot$m and the presence of fractures. These fractures formed radially on the wall strata, indicating the impact of rock blasting activities on the quarry site.

By comparing the chargeability values obtained from RES2DINV with those in Table 2, the image showing an inverse chargeability model section displayed the locations of weak and hard rocks. At a position about 260 m to 320 m along the profile and a depth of about 30 m, a hard rock has been observed which indicates that the region is not much affected by the rock blasting. The whole profile is affected by the active blasting activities taking place in the area with the exception of the hard rock zone. The spontaneous potential values ranging from 0.45 mV to 0.63 mV were found to be high spontaneous potential zones (weak rock zones). Weak rock zones were delineated at distances of about 70–130 m and 360–400 m along the profile, at depths of approximately 20 m and 25 m, respectively. The region with high spontaneous potential values indicates the weak zone region as a result of active rock blasting.

The cross-sections shown in Figure 15, Figure 16, and Figure 17 are resistivity, induced polarization and spontaneous potential, respectively, for Profile 5. The profile was taken from north to south between the two rock quarries, starting from latitude 12.006848°N, longitude 8.605881°E and ending at latitude 12.015819°N, longitude 8.590726°E, with a profile length of 200 m and an electrode spacing of 5 m. The RES2DINV inversion generated for this profile showed the depths to the granitic bedrock at 28.7 m, revealing that the subsurface nature of the investigated area can be grouped into three layered zones. The top layer which is resistive in nature extends to a depth of about 7 m, with resistivity ranging between 100 $\Omega \cdot$m and 200 $\Omega \cdot$m. By comparing the resistivity values with those in Table 1, the layer is found to be highly weathered rock (gravels). This is underlain by a middle layer that is uniformly distributed along the profile, with a thickness of about 12 m and resistivity values ranging from 200 $\Omega \cdot$m to 1000 $\Omega \cdot$m. The layer is found to be partially weathered basement complex rock. The third layer has resistivity values greater than 1000 $\Omega \cdot$m and is found to be a fresh basement complex (granite). The breakage appeared from about 55 m to 85 m along the profile due to the inability to position electrodes caused by rock outcrop in the region. The highest resistivity value recorded along this profile was 17911 $\Omega \cdot$m. The RES2DINV showed a thick weathered bedrock, as noticed by the presence of residual soil materials that were dark blue, pale blue and light green in color. The inverse model resistivity section and geological section showed that the top and middle layers are the affected regions, with low resistivity values less than 1000 $\Omega \cdot$m and the presence of fractures. These factures formed radially on the wall strata, indicating the impact of rock blasting activities on the quarry site.

By comparing the chargeability values obtained from RES2DINV with those in Table 2, the image displays that the whole profile reflects weak rock zones, with the exception of positions from 60 m to 70 m. The breakage appeared from about 55 m to 85 m along the profile due to the inability of electrodes inserted caused by rock outcrop in the region. This indicates that the profile is highly affected, disintegrated due to the rock blasting activities taking place in the quarry site. The spontaneous potential contour map displayed a region of high and low spontaneous potential values. The values ranging from 0.11 mV to 0.21 mV were found to be high spontaneous potential zones (weak rock zones). The high values which appeared in most parts of the profile delineated the weak rock zones. At about positions from 50 m to 200 m with a depth of about 30 m, the weak rock zones, which occurred due to active rock blasting, were delineated.

The results obtained from inverse resistivity model sections and geological sections of Profiles 1–5 show high resistivity values ranging from 3088 $\Omega \cdot$m to 109264 $\Omega \cdot$m, 1028 $\Omega \cdot$m to 2026 $\Omega \cdot$m, 1250 $\Omega \cdot$m to 4471 $\Omega \cdot$m, 1587 $\Omega \cdot$m to 48712 $\Omega \cdot$m, and 1914 $\Omega \cdot$m to 17911 $\Omega \cdot$m, respectively. The high resistivity zones in Figure 3 indicate the hard rock or fresh basement complex (granitic) rock zones, which do not affect or show a negative impact on active rock blasting. Observations of Figure 3 and Figure 9 at positions of about 50 m to 180 m and 75 m to 165 m along Profiles 1 and 3, respectively, indicate an outcrop of fresh basement complex (granitic) rock with a depth of 105 m. The high resistivity values indicate that the regions are not affected by the active rock blasting. However, the results show that resistivity values range from about 200 $\Omega \cdot$m to 1000 $\Omega \cdot$m, indicating that the weak rock zone or region is highly affected by the active rock blasting. The region has been disintegrated and fractures which formed radially on wall strata have been observed physically. The vibration and noise produced during rock blasting contribute much to disturbing and disintegrating the regions. The affected regions are considered to be partially weathered complex rock or weak rock zones. The low resistivity values less than 200 m indicate a top layer or highly weathered basement complex (clay and gravels).

Across all profiles, the subsurface generally consists of three layers: a top layer of highly weathered material (clay and gravels) with low resistivity (<200 $\Omega \cdot$m), a middle layer of partially weathered basement rock (200–1000 $\Omega \cdot$m), and a bottom layer of fresh granitic basement rock (>1000 $\Omega \cdot$m). The top layer is shallow throughout, suggesting that the surface strata are consistently vulnerable to the effects of blasting. In contrast, the depth of the fresh granitic rock varies notably: Profiles 1 and 3 have the deepest outcrops at around 105 m, while Profiles 2, 4, and 5 reach fresh rock at shallower depths of 28.7 m to 57.7 m. This variation reflects natural differences in rock integrity, likely caused by localized weathering and heterogeneity in the basement complex. The partially weathered middle zones appear in all profiles, but their lateral extent differs, with Profiles 4 and 5 showing more widespread weak areas. These zones align with regions most affected by blasting-induced fractures, highlighting how rock degradation and structural weaknesses vary across the quarry site.

The results obtained from inverse chargeability model sections and geological sections for Profiles 1–5 indicate regions with low and high chargeability values. The regions with low chargeability values were considered to be weak rock zones and regions with high chargeability values were considered to be hard rock zones. The weak rock zones are the regions highly affected by the active rock blasting. The two zones are considered to be partially weathered basement complex rock and fresh basement complex (granitic) rock. The partially weathered basement complex zones were the regions highly affected by the active rock blasting activities. The spontaneous potential contour map sections for Profiles 1–5 showed the regions of low and high spontaneous potential values. The regions of low spontaneous potential values suggest the regions with no flow of fluid and highly intact, indicating the hard rock or fresh basement complex rock zone. The regions of high spontaneous potential values indicate locations with the possibility of fluid flow or weak rock zones or partially weathered basement complex rock, and they are the affected regions. However, weak rock zones identified by intermediate resistivity values consistently align with low chargeability and high spontaneous potential readings, demonstrating strong agreement among the three methods. In contrast, fresh granite zones with high resistivity correspond with high chargeability and low spontaneous potential values, indicating structurally competent rock that remains largely unaffected by blasting [19], [20].

Thus, the study focused on radially directed fractures towards the quarry site. From studies of rock blasting, the strains/stresses pervade the nearby environment and can only cause significant impact when they exceed the strength index of the country rocks, but existing fractures can be amplified by recurring propagating stresses and strains. The present study has shown that present radial fractures have not propagated much deep down and possibly much far away transversely; their existence can affect the intrinsic stress distributions in the area. This has been demonstrated at the Babawa quarry site, where a building located nearly half a kilometer away was cracked due to recurring blasting activities. The quarry site could be stable now; however, the recurring blasts, coupled with the establishment of engineering structures within the area brought by human population increase, could be a source of concern for the stress and strain distributions in the area.

The study revealed the depth extent of fracturing within the basement complex rocks at the Babawa main quarry site in Gezawa, Kano State, Nigeria, which would have otherwise appeared relatively homogeneous. From the result obtained, the maximum depth of fracturing was found to be about 105 m, located between longitudes 12.013369°N and 12.015819°N and latitudes 8.590726°E and 8.600092°E. The stratigraphic setting of the study area was identified to consist of gravels as the top layer, followed by a partially weathered basement complex as the second layer, which is then underlain by the fresh basement complex rock extending to greater depths. This study demonstrates how blasting of the quarry has greatly impacted the partially weathered basement complex, causing radially oriented fractures to form, with fresh granitic basement experiencing less or no damage.

Moreover, the study quantified the fractures in terms of their depth and spatial extent and showed how subsurface stress propagation from quarry blasting can affect both rock mass integrity and groundwater flow in the surrounding ecosystem. The results thus offer an important perspective on engineering planning and environmental management in the region. This emphasizes the importance of proper management and monitoring of quarrying activities, stress distribution around quarries, and appropriate mitigation measures to prevent damage to existing structures in the vicinity and changes to groundwater systems. The study also offers a geophysical reference that can help manage quarries sustainably and direct the safe development of local civil infrastructure. In order to gather more precise information on the subsurface conditions of the quarry site, it is recommended that additional research employing integrated geophysical techniques and upgraded equipment be necessary.