This manuscript thoroughly investigates the effects of temperature variations on the physico-mechanical properties of limestone taken from the Nowshera formation in northwestern Pakistan. The rock samples were subjected to heat treatment at various temperatures, ranging from 150 °C to 600 °C for 24 hours. Additionally, the samples underwent freeze-thaw cycles, alternating between room temperature and -40 °C, with each cycle lasting 8 hours (4 hours of freezing followed by 4 hours of thawing). Both destructive tests (uniaxial compressive strength, point load index) and non-destructive tests (specific gravity, ultrasonic pulse wave velocity, porosity, and water absorption) were performed to evaluate the rocks' responses to these temperature variations. The density of induced fractures was calculated at the investigated temperatures and after 50 and 100 freeze-thaw cycles. The results indicate reductions in uniaxial compressive strength (UCS), specific gravity, ultrasonic pulse velocity (UPV), and point load (PL) strength with increasing temperature or number of freeze-thaw cycles. After thermal treatment at 600 °C, UCS decreased by 71 %, point load strength by 74 %, UPV by 49 %, and specific gravity by 7.8 %. Similarly, after 100 freeze-thaw cycles, these properties decreased by 23 %, 19%, 15%, and 2.6%, respectively. Conversely, fracture density, porosity, and water absorption increased with elevated temperatures and freeze-thaw cycles. At 600 °C, increases of 2.51 % in fracture density, 66.5% in porosity, and 67% in water absorption were observed. Additionally, after 100 freeze-thaw cycles, these properties increased by 1.44 %, 10 %, and 12.8 %, respectively. Significant changes in all properties were noted when the temperature exceeded 300 °C or the number of freeze-thaw cycles surpassed 50. These findings highlight the degradation of rocks and alterations in their physico-mechanical properties due to thermal variations, which have important implications for industries such as mining and construction.

This study utilizes advanced seismic methods to investigate the complex geodynamic processes beneath the West Burma, Shan-Thai, Indo-China terranes, and the Gulf regions of Southeast Asia. Through the comprehensive analysis of teleseismic waveforms from 25 seismic stations across Malaysia, Myanmar, and Thailand, crustal anisotropy and the depths of the Conrad and Moho discontinuities are investigated, while also mapping the topography of the mantle transition zone (MTZ) discontinuities at 410 and 660 km. Utilizing H-K stacking and Common Conversion Point (CCP) stacking, this study provides detailed estimations of crustal thickness (H) and Vp/Vs ratios (k), highlighting significant crustal thickening in the West Burma Terrane consistent with subduction processes beneath the Sunda megathrust. The gradual increase in Moho depth within the Shan-Thai Terrane towards the Indo-China Terrane boundary, alongside Conrad discontinuity variations, underscores its complex tectonic evolution. In contrast, the Indo-China Terrane exhibits pronounced crustal thickening, reflective of its intricate collisional history. Additionally, observations in the Gulf regions indicate shallower crustal thickness and evidence of mantle upwelling, with implications for seismic risk assessment and geodynamic modeling in Southeast Asia.

Reservoir classification depends on several parameters tied to different aspects of a Petroleum system. The fundamental approach for any classification begins with identifying types of petroleum structures or traps. As most structures are complex, an innovative approach combining two or more approaches to improve subsurface mapping is being suggested in this work. This paper highlights two prime attributes for analysing the vertical and horizontal parameters of seismic data. The criteria employ mapping of the thickness and the continuity of a reservoir which can be mapped simultaneously using a single technique to classify a reservoir. The Maari field consists of a complex depositional system which varies from fluvial, deltaic to shallow marine and this heterogeneity and lateral continuity poses challenges in mapping the reservoir. Therefore, the use of multi-attribute analysis poses an innovative approach to overcome these mapping challenges. The spectral decomposition study of the Maari field leads to the estimation of the optimal frequency that belongs to the targeted reservoir and is indicative of the thickness of the layer. For an instantaneous phase, it highlights the stratigraphic boundaries, as the phase of events is consistent within the reservoir section but changes at the top and bottom of the reservoir. The instantaneous phase characteristic is a valuable tool for delineating formation and understanding depositional patters. Geological features such as channel thickness, fault boundaries, and continuity of reservoir sands can also be conveniently mapped using this technique.

REB-bulletins of CTBTO from the period 2000-2023 were used for simple statistical evaluation of the travel time residuals of P-waves detected at the epicentral distance from 30° to 90° arrived from the seismic events of magnitude 5 or greater, with hypocentre no deeper than 50 km. While histograms of time residuals calculated for individual stations of the International Monitoring System CTBTO show expected unimodal (Gaussian) distribution, curves expressing distribution of the arithmetic means and medians calculated from data of these individual stations are bimodal. This bimodality can be explained by the sum of two Gaussian curves related to groups of “fast” and “slow” stations, with a modus difference of about 0.4 to 0.5 seconds. Although discussed bimodality is best visible on residuals related to phases detected at the epicentral distance 70° to 90°, it is evident that also curves related to the nearest evaluated phases (from 30° to 50°) are the sum of two Gaussian curves. So, the reason for bimodality should be sought in the upper mantle or crust, which is consistent with the assumption of “two kinds” of the continental lithosphere (Poupinet et al., 2003). The distribution of “fast” and “slow” stations on the map corresponds with published results of global seismic tomography studies.

Red-bed soft rocks are commonly found in the bank slopes of reservoirs in southwestern China. The macroscopic mechanical behavior of red-bed soft rock is closely related to its microscopic particle structure. When studying the physical mechanism of landslide and collapse of red-bed soft rock slope, it is necessary to pay attention to the variation of its microstructure. Both CT scanning and optical microscope can observe the microscopic particle structure of the red-bed soft rock. However, quantitative analysis methods for these microscopic observation images are still rare. In this study, an optical microscope is used to observe a series of sections of the red-bed soft rock in the Three Gorges reservoir area. The image recognition method based on edge detection is adopted to extract the particle structure of the red-bed soft rock section from its microscopic image. A comparative analysis of various edge detection operators reveals that the Canny operator yields the most distinct particle contours with minimal distortion, effectively preserving the original morphology of particles and cement. Furthermore, a non-regular-shaped particle size representation is defined to statistically analyze the particle sizes of red-bed soft rocks. The heterogeneity index calculated using grain size difference was used to quantitatively evaluate the degree of heterogeneity in the microstructure of red-bed soft rock. Comparing the observed images and calculated rock particle data showed that this index accurately reflects the micro-geometric heterogeneity of the microstructure images. These findings provide a method for the quantitative analysis of the microstructure of red-bed soft rocks, offering valuable insights into their mechanical behavior.

Satellite gravity data can be used in this study to characterise hitherto unexplored regions and enhance scientific understanding of the studied area. However, the geological ambiguity of the study area makes it challenging to figure out the geological interpretation within and around the area. Therefore, this work focused on the Garyan area in the northwest part of Libya for the purpose of identifying geological structures. The Garyan region is a part of Jabal Nafusah (central Jabal) due to its geographic location and the character of the escarpment. The gravity data was analysed, designed, and developed into a geophysical model using the Oasis Montaj programme. Several analytic techniques are applied to gravity datasets for subsurface structure investigation, including (TDR) tilt derivative, (THG) total horizontal gradient, (PS) Power spectrum technique, (AS) Analytical signal, and (ED) Euler deconvolution. The results identified the presence of faults trending in different orientations (N-S, NW-SE, E-W, NNW-SSE, NE-SW), with source depths ranging between 300 and 2300 m, which indicates a complex tectonic history in the area. Clearly, this work will reduce the ambiguity of geological interpretations and provide better information on the dominant trends for future exploration activities in the study region. It also detects the contacts of density variation and estimates the depth of the gravity sources from satellite-EIGEN-6C4 gravity data.

Many papers on axial compression tests of coal-rock combined bodies have observed the failure of rock components. However, the failure mechanism of the rock component has been the focus of debate among many scholars. One view is that the failure of the rock is due to the energy released during coal failure; the other view is that the failure of the rock is due to the inconsistent coal-rock lateral deformation resulting in tensile stress on the rock side of the coal-rock interface. In response to these two controversial failure mechanisms, coal-rock combined bodies with three coal-rock interface bonding methods (AB glue, direct contact, and graphite fluoride) were designed, and the axial compression tests were carried out. The results show that: (1) the damage cracks of the combined body are mainly distributed on the coal component, the stronger the interface adhesion, the easier it is to crack. (2) All three combined bodies showed rock component damage, and the number of cracks in the rock component was different at different interfaces of the combined bodies. The stronger the interfacial adhesion is, the easier it is to produce cracks, and the more the number of cracks in the rock component is. (3) The destruction of rock components is the result of energy transfer mechanism. Under the action of the test machine, the coal component is destroyed first, and a large amount of elastic energy is released instantaneously to the rock component, which reaches the energy storage limit of the rock and stimulates the destruction of the rock component. The tensile stress at the coal-rock interface plays a certain role in the propagation and penetration of cracks in the rock, but does not determine the damage of rock components. (4) The stronger the interfacial bonding, the greater the strength of the combined body. Based on the D-P criterion, the strength of coal rock at the interface of coal-rock combined body was analyzed. The strength of the coal body at the interface increases to a certain extent, and the strength of the rock mass at the interface decreases to a certain extent. (5) The stress distribution model of coal-rock combined body was constructed, and the internal mechanism of coal-rock component failure was further clarified. The coal and rock mass at the interface are the weak areas of the combined body, and the stress concentration in this area is the largest and the possibility of damage is the largest.

Surface waves typically constitute the dominant component of the seismic record, thus yielding the highest signal-to-noise ratio. Their propagation velocities are closely linked to the shear-wave velocity of the medium. In this study, we provide a review of the basics of surface wave analysis, focusing on Multichannel Analysis of Surface Waves (MASW). We illustrate this approach through four case studies representing common geophysical tasks. By incorporating basic surface wave dispersion analysis into standard refraction surveys, we aim to reduce solution ambiguity and enhance knowledge without incurring additional costs. In Case Study 1, we address the topic of vertical geophone natural frequencies and compare data acquired simultaneously, concluding that even with 10 Hz geophones, surface wave dispersion analysis can yield satisfactory results.

In the present study, a scheme based on fuzzy finite element method was provided for uncertainty quantification of liquefied saturated soil response under dynamic loading. In this respect, the coupled dynamic equations which are known as u-p equations were used, and instead of crisp values for input parameters, including permeability coefficient, specific mass of the soil, compressibility and shear modulus, their fuzzy numbers were used. At the end, displacements and pore water pressure created during earthquake were reported as fuzzy numbers. After verifying procedures of fuzzy analysis by experimental results from the centrifuge model test No. 1 from the VELACS project, several membership grades were considered. Firstly, the effect of fuzzification of each input soil parameter investigated individually, and then effect of considering all four input soil parameters as fuzzy numbers was analyzed by developed method. It was indicated that results of the analysis during the effective time of the earthquake were strongly influenced by the shear modulus and partially by compressibility modulus, and after this time, it was mainly affected by the permeability coefficient. Also considering uncertainty nature of specific mass of the soil had no significant effect on the results.