Fault occurs when there is a mechanical break or generic discontinuity within the rock volume. It could also be termed as the displacement in a rock volume by fracturing along a planar interface. A fault initiates or propagates when there is equity between the stress and strength of a rock. Some of the mechanisms that produce high stress within the crust include fluid pressure; lithostatic; geothermal occurrence; tectonic forces as regard to lithospheric plates’ movement; geologic processes such as volcanic activities, folding as well as salt intrusion; and other forces by extraterrestrial bodies . The fault architecture is related to the fault size, orientation, shape, and its interconnectivity . It could also be termed as the overall distribution of fault’s displacement into subfaults.
Any event that occurs suddenly in nature could be termed as natural disaster. Such events are wildfire, solar flare, sinkhole, cyclone, drought, thunderstorm, tornado, flood, volcanic eruption, landslide, hurricane, tsunami, and earthquake. Of all these events, earthquake has been regarded as the greatest disaster . It comes swiftly, without giving uncertainty room for its occurrence . This phenomenon is so scary as a result of its destructiveness to lives, properties, and economy. Generally, earthquake is believed to occur within tectonic margins, but record has showed that it could also occur outside the tectonic margins, as in the case of Nigeria .
Nigeria is situated on a seismic inactive plate, but the rate at which tremors are being recorded (via instrumental and/or historical platforms) from 1933 across the country till the recent one that occurred in Federal Capital Territory, Abuja, in 2018 had proved that Nigeria is no longer safe from earthquake occurrence(s), which requires further investigations. Nigeria resides on the eastward of the Atlantic Ocean, which is attached to the passive margins (Figure 1) toward the south and southwestern regions of the country. Geologically, there have been consistent openings or movement in the Atlantic margins since the Jurassic (201.3 – 145 Mya) to present . Unlike the active margins (such as the Pacific), which is associated with devastating earthquake occurrences as a result of subduction tectonics, passive margins (such as Atlantic) are believed to be stable and quiet; and due to this, little awareness and preparation have been made for earthquake occurrences along the passive margins, especially Nigeria and other countries in the coastal region of West Africa.
For about 85 years of seismic activities in Nigeria, there was no record of loss of life nor damage of properties, but of recent, damage to properties were observed. The geological structures and some human activities have aided the mechanisms that are responsible for the seismic events in Nigeria . The years of occurrence of these events are 1933, 1939, 1964, 1984, 1985, 1987, 1990, 1994, 1997, 2000, 2006, 2009, 2016, and 2018 [7,8]. In recent time, these events have begun to produce a scary outcome, which could be likened to a detonation of a small fission bomb as reported by . If this event is not properly monitored, seismic activities with greater magnitude than those recorded earlier (magnitude of up to 4.5) could be triggered in the region . According to the literature, some locations that have been affected by tremors so far include Saki, Igbogene, Kwoi, Sambang Dagi, Dan Gulbi, Kano, Kombani Yaya, Lupma, Abuja, Yola, Gembu, Abeokuta, Oyo, Ibadan, Ogbomoso, Akure, Shagamu, Ijebu-Ode, Lagos, Okitipupa, Warri, Ile-Ife, Ijebu-Remo, Ohafia, Kundunu, Obi, Akko, Kurba, Jerre, Benin, Edo, Jushi-Kwari, Akure, and Abomey-Calavi [3,6,11,12]. Their studies had shown that more than half of the seismic events in Nigeria occurred in southwest ([SW]; Figure 2). This shows that southwestern region of Nigeria is more vulnerable to tremor occurrence compared to other zones. However, the epicenters of these earthquakes with their locations are presented in Table 1.
Historical seismic events in Nigeria (adapted from )
|Date of event||Felt area||Probable epicenter||Intensity/magnitude|
|June 22, 1939||Lagos, Ibadan, Ile-Ife||Akwapin fault in Ghana||6.5 ML|
|July 28, 1948||Ibadan||Close to Ibadan|
|July 2, 1961||Ohafia||Close to Ijebu-Ode|
|December 21, 1963||Ijebu-Ode||Close to Ijebu-Ode||V|
|April 23, 1981||Kundunu||At Kundunu village||III|
|October 16, 1982||Jalingo, Gembu||Close to Cameroun Volcanic Line||III|
|July 28, 1984||Ijebu-Ode, Ibadan, Shagamu, Abeokuta||Close to Ijebu-Ode||VI|
|July 12, 1984||Ijebu Remo||Close to Ijebu-Ode||IV|
|August 2, 1984||Ijebu-Ode, Ibadan, Shagamu, Abeokuta||Close to Ijebu-Ode||V|
|December 12, 1984||Yola||Close to Cameroun Volcanic Line||III|
|June 18, 1985||Kombani Yaya||Kombani Yaya||IV|
|July 15, 1986||Obi||Close to Obi town||III|
|January 27, 1987||Gembu||Close to Cameroun Volcanic Line||V|
|March 19, 1987||Akko||Close to Akko||IV|
|May 24, 1987||Kurba||Close to Kurba village||III|
|May 14, 1988||Lagos||Close to Lagos||V|
|June 27, 1990||Ibadan||Close to Ijebu-Ode||3.7 ML|
|April 5, 1990||Jerre||Close to Jerre village||V|
|November 7, 1994||Ijebu-Ode||Dan Gulbi||4.2 ML|
|1997||Okitipupa||Close to Okitipupa Ridge||IV|
|2000||Edo||Siluko, Edo||4.5 ML|
|August 15, 2000||Jushi-Kwari||Close to Jushi Kwari village||III|
|March 13, 2000||Benin||55 km from Benin City||IV|
|March 7, 2000||Ibadan, Akure, Abeokuta, Ijebu-Ode, Oyo||Close to Okitipupa||4.7 ML|
|May 7, 2000||Akure||Close to Okitipupa||IV|
|May 19, 2001||Lagos||Close to Lagos City||IV|
|August 8, 2002||Lagos||Lagos City||IV|
|March, 2005||Yola||Close to Cameroun Volcanic Line||III|
|March 25, 2006||Lupma||Close to Ifewara||III|
|September 11, 2009||Abomey-Calavi||Close to Benin||II|
|November 5, 2011||Abeokuta||Close to Abeokuta||4.4|
|July 10, 2016||Saki||Oyo State||IV|
|August 10, 2016||Igbogene||Bayelsa||III|
|September 11, 2016||Kwoi||Kaduna State||III|
|September 12, 2016||Sambang Dagi||Kaduna||III|
|September 7, 2018||Abuja||Mpape||3.0|
Critical review of the previous works has revealed that tremor occurrence in Nigeria could be attributed to regional stress, presence of weakened zones in the crust, and transfer of stress from plate boundaries [3,6,7,8,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]. The West African Craton and Congo Craton bounded the Nigerian Basement Complex in the west-northwest and east-southeast directions, respectively. This could have deduced the stress acting in this orientation, because records of tremors in Nigeria have been along this orientation [26,27]. Regional stress could cause intraplate earthquakes on preexisting faults within the crust that are of low strength. When the intrusive rock (magma) strength is weaker than the host, this could generate a localized stress within the body of rock. Rock intrusions in the sedimentary terrains of Nigeria could have resulted to sufficient stress capable of causing tremors. As reported by Short and Stauble , stress generated as a result of upwelling magma deforms the crust, which leads to faults. Over (geologic) years, these faults are covered by sediments that have formed the midplate structures, which are subjected to tectonic compressional stress . As the stress continues, a failure will occur at the spot of initially fractured zone within the pristine rock, which could result in intraplate tremors . All the aforementioned factors can create fault in the crust which could be a reason for the occurrence of tremors in Nigeria. This has necessitated this study to map the crustal fault architecture along Lagos–Ore axis, SW Nigeria using the high-resolution aeromagnetic data (HRAD). The HRAD is a highly efficient geophysical tool that delineates geostructural features such as shears, faults, and dyke . Among the researchers who have demonstrated the effectiveness of HRAD in delineation and mapping of faults in Nigerian shore include Oladejo et al. , Awoyemi et al. [30,31], and Awoyemi et al. . The outcome of this study will enable the masses to know the routes/channels of these seismic energies whenever it is released.
2 Geology and brief tectonic activity of the study area
The study area falls within the latitude 6° 05′ 00″ to 7° 25′ 00′ N and longitude 2° 43′ 00″ to 4° 31′ 00″ E, with elevation ranges between 85 and 375 m. The geology of Nigeria is of the reorganized Basement rocks in western part of Africa [9,35,36], which dissociates West Africa from Congo Cratons [3,9,37,38,39]. These rocks are composed of the geological features from African igneous and meta-sedimentary rocks . The two obvious geological settings in Nigeria are the Sedimentary Basins and the Basement Complex [3,40,41,42,43]. These two geological settings are well represented in the study area. Lagos lies on Dahomey (Benin) basin – one of the Nigerian sedimentary terrains, while Ore is situated on the Basement complex of SW Nigeria (Figure 3a).
Dahomey basin is located in the SW Nigeria covering Ondo, Ogun, and Lagos states. Dahomey Basin encapsulates the onshore and offshore zones of this region. The onshore includes the region where the Tertiary and Cretaceous sedimentary rocks are revealed along the quarries and roadcuts . This basin is bounded at the west of Niger–Delta basin and the Basement rocks to the north. Both basins are of course low lying, as expected of a basin. The Dahomey basin extends beyond Nigeria and, like the Niger Delta, seems to have some oil deposits, although the former is far less explored than the latter. The Continental basin of the former is not as extensive, and the seabed slopes away relatively steeply from shore; while in the central Niger–Delta, the seabed slopes away gently, making for a wider area continental shelf. Lagos state as a whole is littoral, low-lying, and swampy, except for some areas inland, the Ogun, Osun, Opara, Yewa, and Weme rivers among others drain into the various lagoons and creeks that wind their way through the terrain, such as the Lagos and Lekki lagoons or the Badagry creek. The geology of Dahomey basin is mainly composed of shale and sand, with some intercalations of limestone. The limestone thickens toward the west of the basin as well as down dip of the coast and its environs. As reported by these researchers [39,44,45,46,47,48,49,50,51,52,53], the lithostratigraphic formations of this basin from Cretaceous to Tertiary are grouped as Abeokuta Group (Cretaceous), Ewekoro (Paleocene)/Akinbo Formations (Late Paleocene – Early Eocene), Oshosun Formation (Eocene), llaro Formation (Eocene), Coastal Plain Sands/Benin Formation (Oligocene to Recent), and Alluvium (Recent age; Figure 3b).
Ore is one of the major towns in Ondo state, which is constituted by the Pre-Cambrian Basement rocks of SW Nigeria (Figure 3a and b) [35,54], though some parts of the state are constituted by the formations of Dahomey basin. The Basement Complex of SW Nigeria is chiefly composed of metamorphic and crystalline rocks of over 550 million years old [55,56]. The crystalline Basement rocks of SW are grouped into Migmatite-Gneiss, metasedimentary and metavolcanic rocks (which is also referred to as Schist Belt), and Pan-African Older Granite [57,58]. The predominant rock in Ore is granite. This rock is massively distributed, which can contribute to the state economy if properly mined. Further readings about the Basement Complex of SW Nigeria have been discussed by [30,41] and .
The seismic events mechanism in Nigeria can be explained in terms of the fractures within the Basement rock and extension of these faults in sedimentary terrain to the Atlantic Ocean . The Nigerian coastal zone lies between the African and South American plates. Some of the recorded tremors around Nigeria, especially in SW Nigeria where these events are highly concentrated, could have been initiated through the built-up stresses around plate boundaries. When these stresses propagate to the center of the plate, it can trigger a phenomenon known as intraplate tremor, especially on already established faults . Some of the important fault systems in Nigeria that have resulted from transcurrent movement include Anka, Kalangai, Ifewara-Zungeru faults . Of all these fault systems, Ifewara-Zungeru fault is the longest already established linear feature in the Basement Complex of Nigeria. This fault is about 250 km long that bisects the Romanche and Chain fracture lines (extending from the Atlantic Ocean to the northeast [NE] part of Nigeria) in the SW and cuts across the St. Paul’s fracture line in the northwest (NW) region of Nigeria [26,34,60] (Figure 2). It took its origin from SW Nigeria and stretched to the NW region of the country, with a north-northeast (NNE)–south-southwest orientation  (Figure 3a). As reported by Akpan and Yakubu , the epicenters of the earthquakes in SW Nigeria fall between the Romanche and Chain Fracture zones (Figure 2).
3 Materials and methods
Many geophysical methods are available for studying the litho-structure of the subsurface at regional dimension. Among the methods are gravity, magnetic, electromagnetic, electrical resistivity, and radiospectrometry; however, magnetic method was employed in this study. Magnetic data can be acquired on ground, in air, and in marine; however, the regional study requires aeromagnetic data. Aeromagnetic data is an essential tool in delineation of Basement rocks and estimation of depth to magnetic sources, even in sedimentary terrain without being disturbed by obstacles [61,62,63,64].
The aeromagnetic data of Lagos–Ore were collected from the Nigerian Geological Survey Agency (NGSA). It composes sheet numbers 278, 279, 280, 281, 278A, 279A, 280A, and 281A; southern part of 259, 260, 261, 262, and 263; as well as western part of 282 and 296 . The data sheets cut across parts of Ogun, Ondo, Oyo, and Osun states as well as the entire Lagos state (Figure 3a and b). The data sets were acquired by the Fugro Airborne Survey Limited for the NGSA in the year 2003–2009 . The survey was conducted in drape mode using the real-time differential GPS at a sensor mean terrain clearance of 75 m. The spacings of both the traverse and the tie lines are 500 and 2,000 m, with the orientation of the flight and tie lines in NW-southeast (SE) and NE-SW, respectively . The data sets were de-cultured, leveled, corrected for International Geomagnetic Reference Field, gridded at an appropriate cell size that amplifies the information contained in the anomaly, and suppresses the latitudinal effect and unwanted signal (noise) [67,68].
The field data (i.e., total magnetic intensity [TMI]) were generated in x, y, and z format (where x, y, and z represent longitude, latitude, and TMI, respectively) on Microsoft Office Excel, so as to export it to Oasis Montaj™ 6.4.2 package . Rockware™ 15 software was used to convert the Universal Transverse Marcator values for x and y to geographic coordinates, in order to juxtapose the resultant maps with the geological map of the study area. In order to enhance the local subsurface features, the residual magnetic intensity (RMI) was generated by removing the regional magnetic field intensity from the data.
In this study, the reduction-to-equator (RTE) filter (on Geosoft Oasis Montaj) was used to enhance the features on RMI data, because the study area falls within the low magnetic latitude zone. RTE makes Earth’s magnetic field and magnetization of the magnetic sources to appear horizontal, centers the peaks of magnetic anomalies over their sources, and removes the magnetic latitudinal influences on RMI . The RTE was performed using two-dimensional fast Fourier transform (2D-FFT) method, with the mean inclination and declination values of −11.10 and −4.90, respectively. Oladunjoye et al.  stated that applying 2D-FFT on potential field data simplifies the complex information that is embedded in the original data. It also improves the quality of data being processed for effective geological deductions. One of such simplifications is to derive maps on which the amplitude of the displayed function is directly or simply related to a physical property of the underlying rocks as well as inherent structural features and other desired parameters. The RTE-RMI data were further subjected to total horizontal derivative (THD) and depth continuation (upward and downward) enhancement techniques using Geosoft Oasis Montaj workstation as applied by [30,31,32, 68,6970,71,72,73].
The THD was applied due to its ability to enhance lineaments, which are structural deformations associated with faults (fractures with displacement) or any other linear features . The mathematical expression for THD  is presented in equation (1). The algorithm used for THD has been presented by Gunn , while further mathematical explanation to this enhancement has been discussed by Blakely . The THD map produced from RTE residual map is as shown in Figures 8 and 10.
Continuation technique enhances transformed observed anomalous potential field to higher or lower elevations, which are known as upward and downward continuations. It also smoothens the residual data by alternating high-frequency or short wavelength anomalies relative to their opposite signatures [68,77]. This technique can be adopted in place of low-pass and high-pass filters . The advantages of continuation technique over low pass and high pass include the following: prominent reduction and separation of near surface (shallow) effects over the deeper ones ; its use in the estimation of depth to magnetic sources; and it retains the signatures of the geopotential field anomaly, provided that the continuation does not intrude into the top of the magnetic body . The amplitude of potential over a magnetic body changes with elevation as an exponential function of wavelength . In downward continuation, the magnetic sources are enhanced at certain depth, such that the measurement’s plane is brought near the source. As reported by , downward continuation maps the components with high wave numbers, enhances the resolution of anomalous bodies, and enables perfect estimation of vertical and lateral extent of magnetic sources. The main shortcoming of downward continuation is that its computation is unstable and deviates from the true features of potential field data due to noise . However, the computation of upward continuation (UC) is stable at higher heights, which accounts for contributions from various sources. The stability of UC and horizontal derivative has made them to be included in computation of downward continuation model  using the Taylor’s series as presented in equation (2).
However, computation of UC from Taylor’s series can be expresses as:
The two continuations require mth-order vertical derivatives of the potential field. At higher order, the vertical derivatives become unstable, which can influence the noise effects . Therefore, the Taylor’s series, especially equation (3) is limited to order 3 . The algorithm used in the two continuations (upward and downward) has been presented by . The resulting maps (Figure 9a–g) revealed the individual depth to magnetic sources (either shallow or deep sources) based on the level of continuation. The magnetic derivatives and other output maps obtained from processing and filtering were then superimposed on the geological map and RTE aeromagnetic RMI map of Lagos–Ore axis using ArcGIS 10.3 and Surfer 11.0 in order to produce the fault map of the study area.
4 Results and discussion
4.1 Aeromagnetic maps
The TMI map of the study area is presented in Figure 4. Figures 5 and 6 are the regional magnetic intensity and RMI maps, respectively. After the removal of the regional effect from the TMI data, most of the unpronounced features on TMI data (Figure 4) become enhanced on the residual map (Figure 6). The magnetic zone apportionment is based on the shape, pattern, and the magnetic intensity on the residual map. Magnetic highs are located toward the northeastern, eastern and northwestern zones of the study area. These signatures could be interpreted as near surface magnetic minerals, with shallow overburdens [57,83,84]. Magnetic lows that trend in NW-SE orientation intruded into the magnetic highs of the study area. These intrusions are also noticed around the southern and northwestern zones of the study area. This could be associated with the depletion of magnetites or network of lineaments, which could be fractured/weak zones or regions with thick overburden [69,85,86,87].
4.2 The RTE-RMI map
Figure 7 displays slight shift in the positions of magnetic anomalies to the NW of the initial positions on the total magnetic anomaly. The RTE filter was applied to the RMI in order to locate the observed magnetic anomalies directly over the magnetic source bodies that caused the anomaly as well as to remove the influence of magnetic latitude on the residual anomalies as shown in RTE-RMI map of Lagos–Ore axis (Figure 7). The RTE filter enables one to determine the gradient along the direction of the greatest rate of change and trend. For RTE, the gradient to the east and north are dx and dy, since the angle of the output grid equals zero at the equator. The color-shaded RTE-RMI map of Lagos–Ore axis is characterized by high (H, depicted by red and pink colors on the legend), medium (M, depicted by green color on the legend), and low (L, depicted by color blue on the legend) magnitude magnetic anomalies. In Figure 7, the high-magnitude magnetic anomaly signatures have magnetic field intensity ranging from 57.9 to 89.1 nT, which are most dominant at the northeastern half and sparingly at northwestern part, and these are the areas of shallow depth to the magnetic sources. The intermediate magnetic anomalies varied in magnetic intensity from 38.2 to 57.9 nT; and they are most prevalent in a convex arc form about northeastern half, these portions are of average depth to the magnetic anomalies. The low magnetic anomalies ranged between 4.02 and 38.2 nT; these are scattered over the study area but abound mostly at the edges, viz., NW, SW, SE, and NE of the area they represent deep depth to the magnetic sources.
4.3 Basement mapping and structural framework
Basement mapping involves delineation of the deep and shallow magnetic sources. These are as exemplified by the RTE-RMI map in Figure 7. The zones of high magnetic intensity indicated by H on Figure 7 are regions of shallow magnetic sources (shallow basement); while those of low magnetic intensity indicated by L are regions of deep magnetic sources (deep basement). The regions indicated by intermediate magnetic intensity (M) lie between the deep and shallow basements. The THD map as revealed in Figure 8 could only distinguish between areas of deep and shallow basement as exemplified by areas of rarity of lineaments . These are as demarcated and or delineated by red lines on the map.
Furthermore, regions of consistent high amplitude on the upward depth continued maps of the study area are regions of deep depth to magnetic sources. However, sharp changes from high-amplitude to low-amplitude anomalies delineated by white rectangles on the maps (Figure 9a–g) are areas of fault zones. Consequently, the faults revealed by UC maps represented by white rectangles are at different depths in the subsurface; there are faults at the western sides of the depth range of 500–2,250 m (Figure 9a,b,f and g) and northwestern sides at the depth range of 1,500–1,250 m parts (Figure 9c–e).
Conversely, regions of increased amplitude denoted by black stars in Figure 9 are regions of shallow depth to top of magnetic sources. The structural framework was based on normalized magnetic derivatives by virtue of its suitability for structural mapping [68,88,89,90,91]. Based thereon, the magnetic lineaments extracted from THD map (Figure 10) have been overlain on RTE-RMI map (Figure 11) using Arc-GIS 10.3 software to obtain the map in Figure 12. Points or regions where the magnetic lineaments are in concordance with the anomalies (represented by white oval shapes) are geologically characterized as ductile deformation zones; while regions where the magnetic lineaments are in discordance with the anomalies are geologically characterized as brittle deformation zones. The associated geological features are either folds for ductile deformation zones or fractures/faults for brittle deformation zones. Brittle deformation zones commonly contain water (especially in shallow bedrock at the depth less than 100 m) and thus allow different chemical and physical weathering processes to take place within the zone, resulting in the decomposition of magnetite to hematite and pyrrhotite to goethite and elemental sulfur .
Most of the E-W lineaments on the overlain map (Figure 12) are associated with ductile deformation zones around Idiroko, Iwopin, Okitipupa, Igbokoda, Ore, northeast of Ijebu-Ode, the southeastern part (Ondo State axis), and the northeastern (Osun State axis) edges. However, the NE-SW lineaments are more associated with brittle deformation zones crisscrossing through the central portion around Atan, Ewekoro, Sagamu, Ijebu-Ode, and toward the NNE zone of the study area. The NW-SE lineaments as observed in the northern part as well as some of the E-W lineaments around Abeokuta also exhibit brittle deformation characteristics. The results of this study are in agreement with the works of  and  who reported that the maximum depth to the aquiferous units within Atan–Ota axis, a brittle deformation zone, varied from 80 to 130 m.
The HRAD of the Lagos–Ore axis have been processed and interpreted. The magnetic anomalies observed had revealed a high magnetic intensity of 57.9–89.1 nT, intermediate magnetic intensity of 38.2–57.9 nT, and low magnetic intensity of 4.0–38.2 nT, which are associated with contracting basement rock features. The lineaments obtained from the THD map revealed areas of various deformations: brittle (associated with faults/fractures) and ductile deformation (associated with folds). The faults revealed by UC are at different depth ranges of 500–2,250 m at the western side and 1,500–1,250 m at the northwestern side of the study area.
Based on the fault architecture of the study area, it could be concluded that the established linear features could be synthetic to the established major Ifewara-Zungeru fault, which could cause a devastating effect when tectonically active. Furthermore, the faults established both at the deep and at shallow depths in the study area could serve as conduits for the passage of seismic energy whenever it is released. Also, reoccurrences of pockets of tremors along Badagry–Idiroko axis are possible, since Allada (latitude 6′39′0″N, longitude 2°9′0″E), which experienced an earthquake of magnitude 4.4 on September 11, 2009, is 128 km away from Lagos. It is therefore recommended that the Nigerian government should pay more attention to earthquake monitoring in the SW part of Nigeria, so that there would be pre-warning to subsequent seismic events. Finally, the established zones of linear features should be considered as the forbidden zones for the nuclear power generation (NPG) in case the Nigerian government intends to explore NPG as an alternative source to hydroelectric power generation in the future.
Critical and thoughtful contributions from the editor and reviewers of this article are highly appreciated. We acknowledge the publication support received from Covenant University, Nigeria.
Olson J. Fracture mechanics analysis of joints and veins [PhD dissertation]. Stanford, CA: Stanford University; 1990. p. 174.
Adagunodo TA, Sunmonu LA, Adabanija MA, Oladejo OP, Adeniji AA. Analysis of fault zones for reservoir modeling in Taa Field, Niger Delta, Nigeria. Pet Coal. 2017;59(3):378–88.
Oluwafemi JO, Ofuyatan OM, Ede AN, Oyebisi SO, Akinwumi II, Babaremu KO. Review of earthquakes in Nigeria: an understudied area. Int J Civ Eng Technol. 2018;9(8):1023–33.
Adagunodo TA, Sunmonu LA. Earthquake: a terrifying of all natural phenomena. J Adv Biol Basic Res. 2015;1(1):4–11.
Adagunodo TA, Oyeyemi KD, Hammed OS, Bansal AR, Omidiora JO, Pararas-Carayannis G. Seismicity anomalies of M 5.0 + earthquakes in chile during 1965–2015. Sci Tsunami Hazards. 2018;37(2):130–56.
Orakpo E. Increasing seismic activities. Vanguard, November 15, 2016. https://www.vanguardngr.com/2016/11/looming-earthquake-measures-avert-devastating-impacts-nigeria-experts/, 2016.
Rabiu AB. FCT earth tremor: scientist urges implement law against illegal mining, borehole digging. Vanguaard, September 7, 2018. https://www.vanguardngr.com/2018/09/fct-earth-tremor-scientist-urges-implement-law-against-illegal-mining-borehole-digging/.
Adagunodo TA, Lüning S, Adeleke AM, Omidiora JO, Aizebeokhai AP, Oyeyemi KD, et al. Evaluation of 0 ≤ M ≤ 8 earthquake data sets in African–Asian Region during 1966–2015. Data Brief. 2018;17C:588–603. .
Oluwafemi J, Ofuyatan O, Oyebisi S, Alayande T, Abolarin J. Probabilistic seismic hazard analysis of Nigeria: the extent of future devastating earthquake. IOP Conf Series: Mater Sci Eng. 2018;413:012036. .
Afegbua KU, Yakubu TA, Akpan OU, Duncan D, Usifoh ES. Towards an integrated seismic hazard monitoring in Nigeria using geophysical and geodetic techniques. Int J Phys Sci. 2011;6(28):6385–93. .
Mohammed ST, Lar UA, Yakubu TA, Umar AK, Dauda D. The review of historical and recent seismic activity in Nigeria. IOSR J Appl Geol Geophysics. 2015;3(1):48–56.
Adekoya JA. Earthquakes in Nigeria. Sunday Sketch Newspaper. 1984, August 26, 13.
Ugodulunwa FXO, Ajakaiye DE, Guiraud M, Hossan MT. The Pindiga and Obi fractures – possible earthquake sites in Nigeria. In: Proceedings of the 3rd International Conference on Current Research in Geophysics and Geophysical Research in Africa. Jos, Nigeria: Faculty of Natural Sciences, University of Jos; 1986. p. 6.
Ajakaiye DE, Daniyan MA, Ojo SB, Onuoha KM. The July 28, 1984 southwestern Nigeria earthquake and its implications for the understanding of the tectonic structure of Nigeria. In: Wassef AM, Boud A, Vyskocil P, editors. Recent Crustal Movements in Africa Journal of Geodynamics, vol. 7. 1987. p. 205–14.
Ajakaiye DE, Olatinwo MD, Scheidegger AE. Another possible earthquake near Gombe in Nigeria on the 18–19 June 1985. Bull Seism Soc Amer. 1988;78(2):1.006–10.
Onuoha KM. Historical perspectives of earthquakes in West Africa. In: Ajakaiye DE, Ojo SB, Daniyan MA, Abatan AO. Proceedings of the National Seminar on Earthquakes in Nigeria. Lagos, Nigeria: National Technical Committee on Earthquake Phenomena; 1989. p. 129–41.
Ananaba SE. Dam sites and crustal megalineaments in Nigeria. ITC J. 1991;1:26–29.
Ojo OM. Survey of occurrences in Nigeria of natural and man-made hazards related to geological processes. In: Onuoha KM, Offodile ME. Proceedings of the International Workshop on Natural and Man-made Hazards in Africa. Jos, Nigeria: Nigerian Mining and Geosciences Society; 1995. p. 10–4.
Elueze AA. Evaluation of the 7 March 2000 earth tremor in Ibadan area, southwestern Nigeria. J Min Geol. 2003;39(2):79–83.
Sunmonu LA, Ayantunji BG, Adabanija MA. The analysis of seismic stability using the fault pattern: a case study of Odokoto, Ogbomoso Southwestern Nigeria. J Appl Sci Asian Netw Sci Inf. 2005;5(3):1–7.
Odeyemi IB. The Ifewara fault in southwestern Nigeria: Its relationship with fracture zones along the Nigerian coast. Toro, Bauchi State: Centre for Geodesy and Geodynamics; 2006. p. 1–13.
Osagie EO. Seismic activity in Nigeria. Pac J Sci Tech. 2008;9(2):1–6.
Akpan AE, Ilori AO, Essien NU. Geophysical investigation of Obot Ekpo Landslide site, Cross River State, Nigeria. J Afr Earth Sci. 2015;127:154–67.
Alaneme KK, Okotet EA. Critical evaluation of seismic activities in Africa and curtailment policies – a review. Geoenviron Disast. 2018;5(24):1–17. .
Eluyemi AA, Saurabh B. A GIS based tectonic map of Nigeria. J Assam Sci Soc. 2016;57(1&2):108–14.
Oladejo OP, Adagunodo TA, Sunmonu LA, Adabanija MA, Olasunkanmi NK, Omeje M, et al. Structural analysis of subsurface stability using aeromagnetic data: a case of Ibadan, southwestern Nigeria. IOP Conf Ser J Phys Conf Series. 2019;1299:012083. .
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Oladejo OP, Adagunodo TA, Sunmonu LA, Adabanija MA, Olasunkanmi NK, Omeje M, et al. Structural analysis of subsurface stability using aeromagnetic data: a case of Ibadan, southwestern Nigeria. IOP Conf Ser J Phys Conf Series. 2019;1299:012083.)| false 10.1088/1742-6596/1299/1/012083.
Short KC, Stauble AJ. Outline of the Geology of the Niger Delta. Am Assoc Pet Geol Bull. 1967;51:761–79.
Eze CL, Sunday VN, Ugwu SA, Uko ED, Ngah SA. Mechanical model for Nigerian intraplate earth tremors. Earthzine. 2011, May 17, 2011. https://earthzine.org/mechanical-model-for-nigerian-intraplate-earth-tremors.
Awoyemi MO, Hammed OS, Falade SC, Arogundade AB, Ajama OD, Iwalehin PO, et al. Geophysical investigation of the possible extension of Ifewara fault zone beyond Ilesa area, southwestern Nigeria. Arab J Geosci. 2017;10(27):1–14. .
Awoyemi MO, Arogundade AB, Falade SC, Ariyibi EA, Hammed OS, Alao OA, et al. Investigation of basement fault propagation in Chad Basin of Nigeria using high resolution aeromagnetic data. Arab J Geosci. 2016;9(453):1–20. .
Awoyemi MO, Ajama OD, Hammed OS, Arogundade AB, Falade SC. Geophysical mapping of buried faults in parts of Bida Basin, North Central Nigeria. Geophys Prospecting. 2018;66:40–54.
Globald, Global distribution of passive margins. 2009, https://en.wikipedia.org/wiki/File:Globald.png#filehistory.
Eluyemi AA, Sharma S, Olotu SJ, Falebita DE, Adepelumi AA, Tubosun IA, et al. A GIS-based site investigation for nuclear power plants (NPPs) in Nigeria. Sci Afr. 2020;7:e00240.
Adagunodo TA, Akinloye MK, Sunmonu LA, Aizebeokhai AP, Oyeyemi KD, Abodunrin FO. Groundwater Exploration in Aaba Residential Area of Akure, Nigeria. Front Earth Sci. 2018;6:66. .
Omeje M, Adagunodo TA, Akinwumi SA, Adewoyin OO, Joel ES, Husin W, et al. Investigation of driller’s exposure to natural radioactivity and its radiological risks in low latitude region using neutron activation analysis. Int J Mech Eng Technol. 2019;10(1):1897–920.
Adagunodo TA, George AI, Ojoawo IA, Ojesanmi K, Ravisankar R. Radioactivity and Radiological Hazards from a Kaolin Mining Field in Ifonyintedo, Nigeria. MethodsX. 2018;5C:362–74. .
Adejumo RO, Adagunodo TA, Bility H, Lukman AF, Isibor PO. Physicochemical constituents of groundwater and its quality in Crystalline Bedrock, Nigeria. Int J Civ Eng Technol. 2018;9(8):887–903.
Usikalu MR, Oderinde A, Adagunodo TA, Akinpelu A. Radioactivity concentration and dose assessment of soil samples in cement factory and environs in Ogun State, Nigeria. Int J Civ Eng Technol. 2018;9(9):1047–59.
Adagunodo TA, Sunmonu LA, Emetere ME. Heavy metals’ data in soils for agricultural activities. Data Brief. 2018;18C:1847–55. .
Ajibade AC, Fitches WR, Wright JB. The Zungeru Mylonites in Nigeria. Recognition of a major tectonic unit. Rev de Geol Phys. 1979;21(5):359–63.
Tsalha MS, Lar UA, Yakubu TA, Kadiri UA. The review of the historical and recent seismic activity in Nigeria. IOSR J Appl Geol Geophysics. 2015;3(1):48–56.
Adagunodo TA, Adeniji AA, Erinle AV, Akinwumi SA, Adewoyin OO, Joel ES, et al. Geophysical investigation into the integrity of a reclaimed open dumpsite for civil engineering purpose. Interciencia J. 2017;42(11):324–39.
Olabode SO, Mohammed MZ. Depositional facies and sequence stratigraphic study in parts of Benin (Dahomey) Basin SW Nigeria” implications on the re-interpretation of Tertiary sedimentary successions. Int J Geosci. 2016;7:210–28. .
Jones HA, Hockey RD. The geology of part of southwestern Nigeria. Geol Surv Nigeria, Bull. 1964;31:101.
Ako BD, Adegoke OS, Petters SW. Stratigraphy of the Oshosun Formation in south-western Nigeria. J Min Geol. 1980;17:97–106.
Omatsola ME, Adegoke OS. Tectonic evolution of Cretaceous stratigraphy of the Dahomey Basin. J Min Geol. 1981;18(1):130–7.
Nton ME. Sedimentological and Geochemical studies of rock units in the eastern Dahomey Basin, southwestern Nigeria [Unpublished PhD Thesis]. University of Ibadan; 2001. p. 315.
Elueze AA, Nton ME. Organic geochemical appraisal of limestone and shales in part of eastern Dahomey Basin, southwestern Nigeria. J Min Geol. 2004;40(1):29–40.
Oyeyemi KD, Aizebeokhai AP, Adagunodo TA, Olofinnade OM, Sanuade OA, Olaojo AA. Subsoil characterization using geoelectrical and geotechnical investigations: implications for foundation studies. Int J Civ Eng Technol. 2017;8(10):302–14.
Adagunodo TA, Hammed OS, Usikalu MR, Ayara WA, Ravisankar R. Data on the radiometric survey over a Kaolinitic Terrain in Dahomey Basin, Nigeria. Data Brief. 2018;18C:814–22. .
Adagunodo TA, Bayowa OG, Usikalu MR, Ojoawo AI. Radiogenic heat production in the Coastal Plain Sands of Ipokia, Dahomey Basin, Nigeria. MethodsX. 2019;6C:1608–16. .
Adagunodo TA, Sunmonu LA, Oladejo OP. Effect of constructing high-rise buildings without a geophysical survey. Nigerian J Phys. 2014;Special Edition September 2014:91–100.
Sunmonu LA, Adagunodo TA, Olafisoye ER, Oladejo OP. The groundwater potential evaluation at industrial estate Ogbomoso Southwestern Nigeria. RMZ-Mater Geoenviron. 2012;59(4):363–90.
Adagunodo TA, Sunmonu LA, Adabanija MA, Omeje M, Odetunmibi OA, Ijeh V. Statistical assessment of radiation exposure risks to farmers in Odo Oba, Southwestern Nigeria. Bull Miner Res Exploration. 2019;159:199–215. .
Adagunodo TA, Sunmonu LA, Oladejo OP, Olafisoye ER. Groundmagnetic Investigation into the Cause of the Subsidence in the Abandoned Local Government Secretariat, Ogbomoso, Nigeria. ARPN J Earth Sci. 2013;2(3):101–9.
Oladejo OP, Sunmonu LA, Ojoawo A, Adagunodo TA, Olafisoye ER. Geophysical investigation for groundwater development at Oyo State housing estate Ogbomosho, southwestern Nigeria. Res J Appl Sci Eng Technol. 2013;5(5):1811–5.
Garba I. Geochemical characteristics of Mesothermal gold mineralization in the Pan-African (600 ± 150 Ma) Basement of Nigeria. Appl Earth Sci IMM Trans Sect B. 2003;112(3):319–25.
Adepelumi AA, Ako BD, Ajayi TR, Olorunfemi AO, Awoyemi MO, Falebita DE. Integrated geophysical mapping of the Ifewara transcurrent fault system, Nigeria. J Afr Earth Sci. 2008;52(4–5):161–6.
Skalbeck JD, Koski AJ, Peterson MT. Estimation of Precambrian basement topography in Central and Southeastern Wisconsin from 3D modeling of gravity and aeromagnetic data. J Appl Geophysics. 2014;106:187–95.
Boubaya D. Combining resistivity and aeromagnetic geophysical surveys for groundwater exploration in the Maghnia Plain of Algeria. J Geol Res. 2017;1309053. .
Alabi AA, Makinde V, Adewale AO, Coker JO, Aluko TJ. Estimation of magnetic contact location and depth of magnetic sources in a sedimentary formation. RMZ-M&G. 2018;66:27–38.
Irumhe PE, Obiadi II, Obiadi CM, Ezenwaka CK, Mgbolu CC. Estimating sedimentary pile thickness, structural lineaments and heat flow in parts of North Central Nigeria from aeromagnetic data. Solid Earth Sci. 2019;4:92–101.
Nigerian Geological Survey Agency (NGSA). The aeromagnetic index map of Nigeria, 2009.
Nigerian Geological Survey Agency (NGSA). Airborne geophysical survey total magnetic intensity map of Lagos–Ore axis, 2008.
Patterson NR, Reeves CV. Effects of the equatorial electrojet on aeromagnetic data acquisition. J Int Geophys. 1985;65(2):55.
Oladunjoye MA, Olayinka AI, Alaba M, Adabanja MA. Interpretation of high resolution aeromagnetic data for lineaments study and occurrence of banded Iron formation in Ogbomoso area, southwestern Nigeria. J Afr Earth Sci. 2016;114:43–53.
Okpoli CC. High resolution magnetic field signatures over Akure and its Environs, southwestern Nigeria. Earth Sci Malays. 2019;3(1):9–17.
Anudu GK, Stephenson RA, Macdonald DIM. Using high-resolution aeromagnetic data to recognize and map intra-sedimentary volcanic rocks and geological structures across the Cretaceous middle Benue Trough, Nigeria. J Afr Earth Sci. 2014;99:625–36.
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Anudu GK, Stephenson RA, Macdonald DIM. Using high-resolution aeromagnetic data to recognize and map intra-sedimentary volcanic rocks and geological structures across the Cretaceous middle Benue Trough, Nigeria. J Afr Earth Sci. 2014;99:625–36.)| false 10.1016/j.jafrearsci.2014.02.017
Ogunmola JK, Ayolabi EA, Olobaniyi SB. Structural-depth analysis of the Yola arm of the Upper Benue Trough of Nigeria using high resolution aeromagnetic data. J Afr Earth Sci. 2016;124:32–43.
Olasunkanmi NK, Bamigboye OS, Aina A. Exploration for iron ore in Agbado-Okudu Kogi state, Nigeria. Arab J Geosci. 2017;10:541. .
Olasunkanmi NK, Sunmonu LA, Adabanija MA, Oladejo OP. Interpretation of high resolution aeromagnetic data for mineral prospect in Igbeti-Moro area, southwestern Nigeria. IOP Conf Ser Earth Environ Sci. 2018;173:012033. .
Miller HG, Singh V. Potential field tilt – a new concept for location of potential field sources. J Appl Geophys. 1994;32:213–7.
Blakely RJ. Potential theory in gravity and magnetic applications. Cambridge, UK: Cambridge University Press; 1996.
Nabighian MN, Hansen RO. Unification of Euler and Werner deconvolution in three dimensions via the generalized Hilbert Transform. Geophysics. 2005;66:13–21.
Pal SK, Vaish J, Kumar S, Priyan P, Bharti AK, Kumar R. Downward continuation and tilt derivative of magnetic data for delineation of concealed coal fire in East Basuria Colliery, Jharia Coal Field, India. J Earth Syst Sci 2017;126:53.
Khalil MH. Magnetic, geo-electric, and groundwater and soil quality analysis over a landfill from a lead smelter, Cairo, Egypt. J Appl Geophys. 2012;86:146–59.
Boschetti F. Improved edge detection and noise removal in gravity maps via the use of gravity gradients. J Appl Geophys. 2005;57:213–25.
Abedi M, Gholami A, Norouzi GH. A stable downward continuation of airborne magnetic data: a case study for mineral prospectivity mapping in Central Iran. Comput Geosci. 2013;52:269–80.
Adagunodo TA, Sunmonu LA, Adabanija MA. Geomagnetic signature pattern of industrial layout Orile Igbon. Adv Architect City Environ. 2015;1(3):14–25.
Hammed OS, Awoyemi MO, Igboama WN, Fatoba JO, Bayode JO, Olurin OT, et al. Ground magnetic for subsurface structural analysis of foundation beds in a sedimentary terrain in south-western Nigeria. FUOYE J Eng Technol. 2018;3(1):33–7.
Okpoli CC, Eyitoyo FB. Aeromagnetic study of Okitipupa region, southwestern Nigeria. Int Basic Appl Res J. 2016;2(7):1–20.
Sunmonu LA, Adagunodo TA, Olafisoye ER, Oladejo OP. Interpretation of groundmagnetic data in Oke-Ogba Area, Akure, Southwestern Nigeria. Adv Appl Sci Res. 2012;3(5):3216–22.
Sunmonu LA, Adagunodo TA, Adeniji AA, Ajani OO. Geoimaging of subsurface fabric in Awgbagba, Southwestern Nigeria using Geomagnetic and Geoelectrical Techniques. Malaysian J Fundamental Appl Sci. 2018;14(2):312–24. .
Salem A, Williams S, Fairhead D, Smith R, Dhananjay R. Interpretation of magnetic data using tilt-angle derivatives. Geophysics. 2008;73:LI–10.
Fairhead D, Wiliiams S, Ben Salem A. Structural mapping from high resolution aeromagnetic data in Namibia using Normalized derivatives. EGM 2007 International Workshop: Innovation in EM, Grav. And Mag. Methods: a new Perspective for Exploration. Capri, Italy, 2007.
Fairhead JD, Williams SE. Evaluating normalized magnetic derivatives for structural mapping, SEG 2006 New Orleans Ext. Abstr. 2006;845–9.
Verduzco B, Fairhead JD, Green CM, Mackenzie C. New insights into magnetic derivatives for structural mapping. Lead Edge. 2004;23:116–9.
Steger HF, Desjardins LE. Oxidation of sulphide minerals: 4. Pyrite, chalcopyrite and pyrrhotite. Chem Geol. 1978;23:225–37.
Joel ES, Olasehinde PI, Adagunodo TA, Omeje M, Akinyemi ML, Ojo JS. Integration of aeromagnetic and electrical resistivity imaging for groundwater potential assessment of coastal plain sands area of Ado-Odo/Ota in Southwest Nigeria. Groundw Sustainable Dev. 2019;9:100264. .
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Joel ES, Olasehinde PI, Adagunodo TA, Omeje M, Akinyemi ML, Ojo JS. Integration of aeromagnetic and electrical resistivity imaging for groundwater potential assessment of coastal plain sands area of Ado-Odo/Ota in Southwest Nigeria. Groundw Sustainable Dev. 2019;9:100264.)| false 10.1016/j.gsd.2019.100264.
Joel ES, Olasehinde PI, Adagunodo TA, Omeje M, Oha I, Akinyemi ML, et al. Geo-investigation on groundwater control in some parts of Ogun State using data from shuttle radar topography mission and vertical electrical soundings. Heliyon. 2020;6(1):e03327. .
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Joel ES, Olasehinde PI, Adagunodo TA, Omeje M, Oha I, Akinyemi ML, et al. Geo-investigation on groundwater control in some parts of Ogun State using data from shuttle radar topography mission and vertical electrical soundings. Heliyon. 2020;6(1):e03327.)| false 10.1016/j.heliyon.2020.e03327. 32051881
Montaj Oasis. Standard edition version 6.4.2 (HJ), Help: Help Topics. Geosoft Inc; 2007.