Shallow Part Research Articles

Development of an Epidemic‐Type Aftershock‐Sequence Model Explicitly Incorporating the Seismicity‐Triggering Effects of Slow Slip Events

AbstractSlow slip events (SSEs) at subduction zone plate boundaries sometimes trigger earthquake swarms and megathrust earthquakes. The causal relationship between SSEs and seismicity has been studied worldwide, but the epidemic‐type aftershock‐sequence (ETAS) model, which is a standard statistical model of seismicity, does not explicitly consider the seismicity‐triggering effect of SSEs. Therefore, if an SSE occurs at a plate boundary, probabilistic earthquake forecasts based on the ETAS model fail to predict observed seismicity. Here, we constructed a statistical model named the SSE‐modulated ETAS model by incorporating SSE moment rates estimated from observation data from the global navigation satellite system into the original ETAS model. Our model assumes a linear or power‐law relationship between the SSE moment rates and seismicity rates and estimates its proportionality constant as a new ETAS parameter. We applied this new model to three SSEs and M 2.5 or greater earthquakes in the shallow part of the Hikurangi Trench, New Zealand. The results show that it is better than the original ETAS model, giving a significant reduction in the Akaike information criterion. In addition, we examined the functional forms (e.g., lag time and power exponent) of the equation relating the moment rate of the SSEs to the seismicity rate. We also examine the influence of SSEs on aftershock productivity. Our model can improve short‐term forecasts of seismicity associated with SSEs if the detection and characterization of SSEs can be done in near real time. Our model is also useful for quantifying characteristics of SSE‐induced seismicity.

Water Masses in the Western Part of the Chukchi Sea in August 2019 and Their Hydrochemical Features

The distribution of water masses in August 2019 in the Chukchi Sea, and their hydrochemical features are i-nvestigated using shipboard data from the transarctic expedition onboard the R/V Professor Levanidov. The work was carried out in the southern shallow part of the sea and in the northern part of the sea outside the 70-meter isobath. Six main water masses were identified: Alaskan and Anadyr Coastal Water (ACW), Siberian Coastal Water (SCW), Melt Water (MW), Summer Bering Sea Water (BSW), Remnant Pacific Winter Water (RWW) and Atlantic Water (AW). Their features are described and analyzed. It was revealed that the water masses of the Chukchi Sea are characterized by a high spatial variability of hydrochemical parameters, especially the BSW, RWW and AW. In the southern part of the Chukchi Sea the presence of very high values of ammonium nitrogen in the bottom layer was noted (up to 12.6 µM). In august 2019, transformed AW, typically residing below 150 m, were observed at a depth of 117–137 meters, characterized by salinity values from 34.2 to 35.7, high content of mineral silicon (93–97 µM), low elevated values of apparent oxygen utilization (240–270 µM), and unusually low N* (a measure of the fixed nitrogen excess relative to phosphorus) values (down to −24.0 µM). At the same time, the AW observed at depths below 140 m did not have such hydrochemical features.

Rock Strength and In Situ Stress Analysis for Wellbore Instability, Fault Stress Regime Prediction, 3D Structural and Geomechanical Modelling in H-field Offshore of Rio Del Rey Basin, Southwest Region, Cameroon

The study involved the determination of strength parameters and in situ stresses in two wells pseudo-named H005 and H008 in a hydrocarbon field located offshore of Rio Del Rey basin. The work was aimed at revealing the stability of formation rocks and fault stress regimes associated with the study wells. The parameters determined employed only empirical correlations and tools since core samples were not available for laboratory experiments. The unconfined compressive strength for the two wells was relatively low varying from 1500 to 3300 psi in well H005 and from 1000 to 4000 psi in well H008. The friction angle varies from 21.0° to 23.0° in well H005 and from 21.0° to 27.0° in well H008. The results of the in situ stress analysis in well H005 indicate a reverse fault stress regime where maximum horizontal stress (SH) is greater than the minimum horizontal stress (Sh), which is in turn greater than the vertical stress (SV) in the shallow part of the well (1028.5–1249 m), while a normal fault stress regime where the vertical stress is greater than the two horizontal stresses was interpreted at a depth from 1250 to 1390 m. Unlike well H005, the entire depth of well H008 under interpretation revealed a normal fault stress regime. The outcome of the 3D geomechanical model closely agrees with the 1D model. It was concluded that the formation rocks are weak, and the wells are dominated by normal fault stress regimes.

Control Mechanism and Support Technology of Deep Roadway Intersection with Large Cross-Section: Case Study

Conventional bolt–shotcrete support technology is usually single-layered, which does not meet the requirements of strength and stiffness for roadway support. Therefore, in this paper, new combined support technology, including a multiple-layered staggered dense arrangement of bolts, multiple-layered laying of steel meshes, multiple-layered pouring of shotcrete, strengthening support of long cables, and full cross-section grouting, is proposed. Specifically, the following new combined support technology process is proposed: first layer of shotcrete (80 mm), first layer of mesh, first layer of bolt, second layer of shotcrete (50 mm), second layer of mesh, second layer of bolt, reinforced cable, third layer of shotcrete (50 mm), and grouting. The results show the following: (1) In the system of a superimposed coupling strengthening bearing arch, compared to a cable bearing arch, changing the support parameters of the bolt bearing arch can significantly vary the bearing capacity. A range of bolt spacing between 0.4 m and 0.7 m is more conducive for a high performance of the bearing capacity of the superimposed coupling strengthening bearing arch. (2) With the increase in the single-layer shotcrete thickness (from 50 mm to 100 mm), the bearing capacity of the shotcrete structure increased rapidly in the form of a power function. (3) After the multi-level bolt–shotcrete support structure was adopted, the ring peak zone of the deviatoric stress of the surrounding rock at the roadway intersection was largely transferred to the shallow part, and the plastic zone of the surrounding rock of the roadway was reduced by 43.3~52.3% compared to that of the conventional bolt–shotcrete support. The field practice model showed that the final roof-to-floor and rib-to-rib convergences of the roadway intersection were 114 mm and 91 mm after 26 days, respectively. The rock mass above the depth of 3 m of the roadway’s roof and sides was complete, the lithology was dense, and there was no obvious crack. The new technology achieves effective control of a deep roadway intersection with a large cross-section.

Quaternary sedimentary processes on the Bahamas: From platform to abyss

Understanding the interaction between sediment production on and export from shallow-water areas of platforms and slopes is primordial when assessing sedimentary processes on a carbonate-platform scale. In this manuscript we explore variations in facies, sediment export, sediment deposition and reorganisation, hydroacoustic- and small-scale sedimentary structures, but also assess the variability in current systems as observed during the Quaternary for the north-facing margin of Little Bahama Bank (LBB) and compare those characteristics with features observed on other slopes surrounding LBB and Great Bahama Bank (GBB).Over the past decade, the northern margin of LBB was explored during a series of oceanographic cruises of the CARAMBAR project, which included the collection of 24.270 km2 of bathymetry data, 6.398 km of very high-resolution seismic profiles, and 42 cores covering water depths ranging from 177 m to 4873 m. This study evaluates the results obtained from the analysis of sediment cores retrieved in the Great Abaco Canyon area (GAC), located between the lower northern LBB slope, which is connected to the abyssal plain. The analysis of the shallower parts of the LBB slope relies on earlier studies and are complementary to our data, and allow for a detailed analysis of the sedimentary processes acting along the entire LBB slope.The data reveal that Quaternary sediment distribution differs when moving from the north-eastern to the north-western LBB slope. The entire LBB slope is dissected by numerous canyons. Gravity processes enriched in coarse platform components occur infrequently and are concentrated within lobes in the east. Only coarse-grained rich bank facies can concentrate coarse grains on this margin. The western LBB slope is mostly influenced by fine-grained platform export and current circulation. The deeper GAC area is dominated by pelagic sediments that are supplied from the canyon sides and through tributaries. The sediment composition confirms that pelagic sediment production and current movements determine the sediment-deposition and redistribution processes at this site.The comparison with other Bahamian slopes demonstrates that a leeward position agrees with high sedimentation rates on the slopes resulting in specific morphologic structures, such as gullies and sediment waves, related to fine-grained sediment export, whereas platform-derived coarse-grained facies are deposited downstream in larger structures, such as canyons, that are not affected by the main wind direction. Slope angle could also have an impact on grain-size export, as it appears that coarse-grained deposits are frequent on steep slopes like those bordering the Exuma Sound basin.

Geological controls on the distribution of gas hydrates in the shallow parts of the gas hydrate stability zone – constraints from seafloor drilling off Taiwan

The presence of gas hydrates is well known in the marine realm southwest of Taiwan due to the widespread distribution of bottom simulating reflectors in seismic records. To learn more about gas hydrate systems and their dynamics at passive and active margins, we drilled boreholes with MARUM-MeBo200 seafloor drill rig at areas where geophysical indications for gas hydrates have been detected in the past. Several gas hydrate proxies like negative chloride anomalies in the pore water, cold spots detected by infrared thermal scans on cores, increased resistivity, and lithological parameters clearly showed the presence of hydrates in the drilled sections. However, gas hydrate was not recovered by MeBo most likely because of small crystal sizes which dissociated during recovery from the seafloor. Three holes were drilled at southern summit of Formosa Ridge down to 126 m below seafloor (mbsf) and recovered sediments from which in situ hydrate saturation values were estimated between 1 and 10% at 15–42 mbsf and even higher values of up to 38% below 100 mbsf. The latter are probably related to the sealing effect of carbonate precipitation which occur at 85–95 mbsf directly above the hydrate-enriched layer. Four holes were drilled at Four-Way Closure Ridge where a maximum drilling depth of 143.90 mbsf was reached. Hydrate presence starts in 65 mbsf continuing down-core with a range of 1–29% gas hydrate saturation in fine-grained homogenous clay. An abrupt change to higher gas hydrate saturation values of up to 80% occurs below 109 mbsf where silty and sandy turbidite layers are often intercalated. Such high gas hydrate contents only occur in the sand layers and not in the fine-grained sediments intercalated to the sand deposits.

Features of the lithological structure of the Lower Cambrian Pestrotsvet Formation near the Oi-Muran reef massif (Yakutia)

Cambrian sections of the Lena Pillars National Park and adjacent areas in the south-east of the Siberian platform have been the subject of paleontological-stratigraphic, lithological, facies, paleogeographic and structural-tectonic studies. In this article we provide a detailed description of the Lower Cambrian Pestrotsvet Formation in the off-reef facies near the Oi-Muran reef massif. The description is given by the coastal outcrops of the Lena River above Sinsk village: 27 “Bachyk” (left bank), 43 and 44 (right bank). The exposed sediments in these outcrops belong to the off-reef shallow part of the open normal saline sedimentary basin adjacent to the Oi-Muran fragment (reef array) of the grand West Yakut Barrier Reef. We conducted a detailed description of the typical part of the section to identify the specifics of sediment accumulation in the Pestrotsvet Formation. A thin alternation of limestone laminae (with thickness varying from 3–5 to 10–20, less often 30–40 cm) was established. They are characterized by a light gray clean, pinkish-gray color, without visible impurities, and burgundy clay with abundant admixtures of ferruginous pigments. The individual intervals of the section are characterized by laminae of maroon marlstone. The rhythmic shift in the section of rocks of different compositions is the result of frequent, however, according geological standards, short-term transgressions and regressions. The origin of some laminae of comparatively pure gray and pinkish-gray limestones that contain abundant remains of cyanobacteria and algae is related to the rock-forming activity of these microorganisms. The materials presented in this article contribute to studies on the off-reef facies of the West Yakut Barrier Reef, one of the oldest reefs on Earth, which played a major role in the emergence of reef biota.

Evaluation of the spatial characteristics of slope erosion using field electrical resistivity measurements

Slope erosion due to rainfall, being a complex and serious problem worldwide, is related to natural hazards and the environment. However, scientific evaluations of slope stability are lacking, and research on the spatial characteristics of slope erosion is scarce. As such, in this study, we have constructed a method of evaluating the spatial characteristics of slope erosion that we combined with electrical measurements; subsequently, we have conducted an in situ model test. We observe a step-type growth trend in the change in resistivity, which was divided into different degrees of erosion using the K-means clustering method. Moreover, we have selected excavated slopes with supporting structures and landfill slopes without supporting structures to evaluate the spatial characteristics of engineered slopes after several months; finally, we have applied the proposed evaluation method. We use seasonal and trend decomposition using loess to remove the noise and randomness in the resistivity data, and we determine the change in resistivity based on the threshold calculated through probability density statistics. We categorize the erosion of slopes into different states and identify a spatial step-type growth trend in slope erosion, which was in good agreement with the spatial distribution characteristics of cracks on the slope. We observe serious erosion at the bottom and shallow parts of both slopes, which indicated a high risk of local collapse according to the spatial characteristics of slope erosion and our slope stability analysis.

Sources, transport, and deposition of metal(loid)s recorded by sulfide and rock geochemistry: constraints from a vertical profile through the epithermal Profitis Ilias Au prospect, Milos Island, Greece

Drill core samples from the Profitis Ilias Pb-Zn-Cu-Ag-Au vein mineralization on Milos Island, Greece provide new insights into (i) the metal sources, (ii) the primary vertical metal(loid) distribution, and (iii) the supergene enrichment processes in a transitional shallow-marine to subaerial hydrothermal environment. Metal contents of unaltered and altered host rocks combined with Pb isotope analyses of hydrothermal sulfides suggest that most metal(loid)s were derived by leaching of basement rocks, whereas the distinct enrichment of Te is related to the addition of Te by a magmatic fluid. The trace element contents of base metal sulfides record decreasing Au, Te, Se, and Co, but increasing Ag, Sb, and Tl concentrations with increasing elevation that can be related to progressive cooling and fluid boiling during the hypogene stage. The formation of base metal veins with porous pyrite hosting hessite inclusions at ~ 400 m below the surface was triggered by vigorous fluid boiling. By contrast, the enrichment of native Au associated with oxidized Fe and Cu phases in the shallower part of the hydrothermal system resulted from supergene remobilization of trace Au by oxidizing meteoric water after tectonic exhumation to subaerial levels. Disseminated pyrite with higher Tl/Pb ratios and locally elevated Hg concentrations relative to vein pyrite reflects infiltration of the host rocks by boiled liquids and condensed vapor fluids. The vertical and temporal evolution of the Profitis Ilias mineralization, therefore, provides unique insights into the transport and precipitation of Au, Ag, Te, and related metal(loid)s by multiple fluid processes.

An experimental study of fault slips under unloading condition in coal mines

To investigate the mechanism of fault slips in coal mines, a biaxial shear experiment was carried out under unloading condition based on the fault F16 in Yima city, China. Two rock samples were used in the experiment and each sample was composed of two triangular sandstone blocks which were put together to simulate the fault. One rock sample was used to do fault slip tests and it was called slip-test sample. The other sample for comparison with the slip-test one was untested, and it was named non-slip-test sample. During the biaxial shear experiment of the slip-test sample, normal and shear strains near the fault, acoustic emission (AE) signals, and the sliding displacement were measured. After the experiment, microscopic profiles of fault surfaces of both rock samples were examined by scanning electron microscope (SEM). In addition, a numerical simulation was conducted to model the slip of the fault F16. The results indicate that: (1) three fault slips occurred during the biaxial shear experiment, and the shear stress, normal and shear strains in the first slip showed the maximum variation among three slips; (2) Shear strains near the two ends of the fault had a more significate variation than that in the middle part, and the typical trend of shear strains was first dropping, then increasing rapidly, and then falling slowly to a specific value during the first slip; (3) The first slip had the largest sliding displacement of 29.89 mu m, and in the first slip three phases including slow slip, main shock and aftershock occurred based on AE monitoring results. (4) On the fault surface of non-slip-test sample, microstructures such as bulges, voids and veins were ubiquitous and notable, making the fault surface much rough, while similar microstructures were few and the fault surface of the slip-test sample was flattened after fault slips; (5) The slipping direction in the shallow part and deep part of the fault F16 were opposite during mining.

On the shapes of deep slopes of radiocesium vertical profiles in lake sediments

The shapes of the deep slope (below the maximum values) of the vertical profiles of radiocesium activity concentrations in the sediment samples taken in 2003–2012 in the Lakes Juodis, Tapeliai and Red lake were studied. The Gaussian shape of the deep slope indicates the migration of radiocesium into the depths of the sediments, and this process is significantly enhanced in some places due to bioturbation caused by tench preparing for hibernation. The exponential shape of the deep slope is typical for sediments in which in winter, in the presence of an ice cover on the lake, thermodynamic mixing occurs in the surface layer caused by the effects of pore water buoyancy. In these sediments, radiocesium dissolved in the pore fluid migrates upwards into the near-bottom water, becoming a source of secondary pollution of the water column. In winter, the presence of such a process is easily determined by the emergence of a layered structure of the water column in the lake and the temperatures of the near-bottom waters exceeding 4 °C. In this case, each layer is characterized by constant standard water parameters (temperature, conductivity, concentrations of oxygen, and trace elements). Complex forms of the deep slope of the vertical profile of radiocesium activity concentrations, combining elements of the exponential and Gaussian forms, indicate the episodic presence of both migration mechanisms.A method is proposed for identifying sediments that are a source of secondary pollution of lake waters by estimating the differences between the normalized logarithms of the radiocesium activity concentrations of the deep slopes (below the maximum concentrations) of its vertical profiles in the sediments of the studied samples and the sample of the carbonate barrier sediments, which were discovered in the shallow part of Lake Juodis in 2003.

Study on the Deformation Mechanisms of the Surrounding Rock and Its Supporting Technology for Large Section Whole Coal Cavern Groups

The control difficulty of whole coal cavern groups is greatly increased due to the characteristics of soft rock with low strength, large sections, and the mutual influence of crossed cavern groups. The large section gas storage cavern group is taken as the research background. In this paper, the equivalent circle method is used to solve the loose circle of a rectangular roadway, and numerical calculation is used to obtain the deformation and stress distribution laws of the surrounding rock under the excavation conditions of large section whole coal cavern groups (WCCG). The deformation and failure mechanisms of the surrounding rock are revealed under the linkage impact between large section whole coal cavern groups. The stratified reinforcement ring concept of “long cable-bolt-grouting” (LBG) was proposed for the stability control of surrounding rock in the WCCG. On the roof of whole coal cavern groups, the supporting configuration of a high-strength bolt with a high pre-tightening force and the high-strength anchor with a high pre-tightening force were determined. On the two sides and floor of the WCCG, the grouting scheme was determined. These two supporting configurations in both the roof and sidewalls were applied to the large section gas storage cavern group. The results show that the surrounding rock presents asymmetric deformation and failure characteristics due to the large excavation area and complex structure. Tensile failure and mixed tensile-shear failure mainly occur in the shallow part of the surrounding rock, while shear failure mainly occurs in the deep part of the surrounding rock. The roof displacement curves show a symmetric distribution and saddle distribution in the low- and high-negative pressure caverns, respectively. The maximum displacements are on the left and right sides of the cavern roof. The range of the loose rings is 3.34 m and 2.54 m, respectively, on the roof and the two ribs. The stratified reinforcement ring support technology of LBG can effectively reduce the failure depth of surrounding rock, and the surrounding rock is in a stable state. The study can provide a theoretical basis for the layout of large section cavern groups and the stability control of surrounding rock.

Sucul Helophorus (Coleoptera: Helophoridae) böceklerinden elde edilen protein ekstraktlarının anti-kanser ve antioksidan özelliklerinin belirlenmesi

In this study, protein extraction was performed from the aquatic insect Helophorus aquaticus (Linnaeus, 1758) and Helophorus syriacus (Kuwert, 1885) species belonging to the genus Helophorus (Coleoptera: Helophoridae). Then, these protein extracts were studied in vitro. These species were collected from the shallow parts of various streams, springs, creeks, ponds and hot springs from Bingöl city centre and its districts between May to June 2017. The protein amount was determined 34.78 mg/mL in the H. aquaticus and 35.14 mg/mL in the H. syriacus, after that he antioxidant capacity of protein extracts was examined. Metal chelating activity was determined as 90-88.5% and DPPH removal activity 53.19-61.7% for H. aquaticus and H. syriacus respectively. Protein samples belonging to both species were tested for cell vitality with WST-1 in PC-3 (prostate cancer) cells with in vitro cell culture. Upon examination of the test results, it has been found out that protein extracts from both of the studied species caused a decrease in cell inhibition. The highest cell inhibition was observed in samples with 1000 μg/mL insect protein extract added. In this study, protein expression providing apoptosis was examined with the Western blot technique after the effective dose was established. By looking at the proteins of Cyt-C and Caspase 3 with the Western blot technique, the efficacy of the protein extracts from both species was demonstrated effectively for the in vitro PC-3 line in non-apoptosis cell death. As a result of the study, insect proteins were shown to support the production of proteins that ensure cell death with the western blot technique.

Enlarged rete pegs with excessive accumulation of melanosomes leading to darker aging spots revealed by histomorphological measurements of internal structures of the epidermis.

Various histological studies of facial pigmented spot sites such as solar lentigo have been reported, but few studies have used quantitative indices by histomorphometric analysis of the internal structure of pigmented spot sites using non-invasive methods. In the present study, to quantitatively elucidate morphological changes in the epidermis in male, darker-pigmented spots and female, light-pigmented spots, indices that characterize the internal structure of the epidermis in pigmented spot sites were measured using in vivo confocal laser scanning microscopy (CLSM). The darkness of pigmented spots on the cheeks of 69 women and 43 men was analysed using image analysis software. The L* value was calculated from RGB values obtained from facial images. The internal structures of pigmented spots on the cheeks of 13 subjects were observed by CLSM. Various parameters were measured using CLSM images from the surface of the stratum corneum to the bottom of the dermal papillae, including the thickness of the epidermis, melanosome content, and shape of the dermal papillae. Mean ΔL* values between pigmented spots and non-pigmented areas of male subjects were significantly increased in the 40s and 50s compared with those of female subjects. Conspicuous pigmented spots increased in the 40s in male subjects and the 50s in female subjects. In CLSM observations, significant increases in the thickness of the epidermis and melanosome content were confirmed in pigmented spots compared with surrounding non-pigmented areas. In particular, melanosome content in the male subject group with dark-coloured pigmented spots increased significantly to about eight times that of non-pigmented areas, and more than double that of the male subject group with light-coloured pigmented spots. From the measurements of quantitative parameters, morphological changes in the epidermis were clearly related to the surface colour tone of pigmented spots. Darker pigmented spot sites tended to show longer rete pegs in the epidermis. Accumulation of melanosomes in epidermal basal cells could be considered to increase with the degree of elongation of rete pegs at pigmented spot sites and, thus, induce darker pigmented spots.

Estimation of Precipitation Fraction in the Soil Water of the Hillslope Vineyard Using Stable Isotopes of Water

This paper presents research related to the estimation of the precipitation fraction in the soil water of a sloped vineyard at the SUPREHILL Critical Zone Observatory (CZO) in Zagreb, Croatia. Numerous investigations have shown that exploration of hillslope soils can be very challenging due to the existence of heterogeneity and different soil properties, as well as due to anthropogenically induced processes, which can affect precipitation infiltration and soil water flow. Within this research, physicochemical soil properties, soil water content (SWC), and isotopic composition of soil water and precipitation (δ2H and δ18O) have been examined. The isotopic signature of soil water was monitored in 24 points, at 4 depths, throughout the hillslope vineyard. Soil water isotopic composition from all monitoring points coincided with the Local Meteoric Water Line (LMWL), with almost no variability at 100 cm depth, which was consistent with the smallest variation of SWC at 80 cm depth and indicated that most of water mixing takes place in the shallower part of the hillslope. Results suggested the existence of heterogeneity, uneven erosion processes in the footslope of the observed vineyard, and different infiltration patterns. Fractions of precipitation varied significantly depending on the depth and position in the vineyard, from approximately 1% up to 98%, where more precipitation fraction has been determined in the surface and subsurface runoff. Additionally, statistical analysis and a more detailed evaluation of precipitation fractions at the 40 cm depth, where wick lysimeters are installed, have shown that Corg content is related to the silt fraction, while the first results indicate that the infiltration patterns were dependent on the common influence of all observed physicochemical properties.

Analyzing the Formation and Evolution of Strike-Slip Faults and Their Controlling Effects on Hydrocarbon Migration and Charging: A Case Study of Tahe Area, Tarim Basin

The Ordovician strike-slip faults system in the Tahe area of the Tarim Basin provides an important opportunity for using 3D seismic data to document the structural characteristics, formation, and evolution of strike-slip faults and their relationship with oil and gas. With high-resolution 3D seismic data, the strike-slip faults are interpreted, classified, and described using the seismic coherence technique. The geometric characteristics, active periods, formation, and evolution process of strike-slip faults are analyzed, and the relationship between strike-slip faults and hydrocarbon accumulation and charging is discussed in this research project. On the map, the primary strike-slip faults on the east and west sides of the Tahe area are relatively sheared to each other, showing an “X” type conjugate fault, and the secondary strike-slip faults are scattered. In the cross-section, the primary strike-slip faults are inserted downward into the Cambrian basement and up to Devonian, and “Single line”, “Y”, “Flower”, and “Parallel lines” structures are observed. Bounded by the top of Ordovician, the deep and shallow parts are vertically segmented, with different structure styles. The switch of the structural style of strike-slip faults is attributed to principal stress. A deep “positive flower” shape of faults was developed in the mid-Ordovician period under the effect of compressive stress. Meanwhile, a shallow “negative flower” shape of faults was developed from the late Ordovician to the mid-Devonian period under tensile stress. The “Compound Flower” shape of deep “positive flower” shape and shallow “negative flower” shape formed by compressive and tensile activities has a wider fracture range, which leads to deep fluid migration and shallow karstification. There are two combinations of deep Ordovician strike-slip faults in the section: “Lower single branch-upper flower type” and “lower single branch-upper single branch type”. The primary faults of the former insertion into the Cambrian basement are associated with homologous secondary faults, while the latter has no derived secondary faults. It has an important impact on reservoir reconstruction and distribution, and the reservoir is controlled by faults. Strike-slip faults not only control the channel of oil and gas migration, but also the horizontal and vertical distribution of oil and gas. The closer the carbonate reservoir is to the primary fault, the more likely it is to form a high yield area. There are four types of oil and gas charging models controlled by strike-slip faults. In the area where the structure is high and the strike-slip faults are sheared relatively to each other, the larger the scale of faults, the more conducive it would be to oil and gas migration and accumulation. Among them, the charging model related to the primary fault has higher oil and gas migration efficiency. This research contributes to analyzing the relationship between strike-slip faults and oil and gas as well as playing a significant role in applications of oil and gas exploration in practical works.

Detection and Characterization of Earthquake Swarms in Nankai and Its Association With Slow Slip Events

AbstractVarious types of slow earthquakes occur in the Nankai subduction zone, among which the slow slip events (SSEs) seem to connect the shallow and deep part of the subduction plate and further trigger seismic or aseismic transients in surrounding areas. This study uses a version of space‐time epidemic‐type aftershock sequence (ETAS) model with non‐stationary background rate to detect earthquake swarms that may be related to SSEs in the Nankai region. We detect 999 swarm sequences including 13,387 earthquakes, accounting for about 18 percent of all M ≥ 1.0 earthquakes in the selected region along the Nankai trough. The detected swarms are mostly distributed in the Hyuga‐nada, Bungo Channel, Kii Channel, and Tokai regions, forming a complementary pattern to SSEs. Nearly 70 percent of swarm events are located in western Nankai, with the southern part characterized by a higher occurrence rate, which is consistent with the smaller recurrence interval of SSEs in this region. By comparing occurrence times of swarm events to those of SSEs, we find that some SSEs are accompanied by enhanced swarm activities during their occurrence periods. In addition, the swarm rates increase to higher levels in the southern part of western Nankai during the 2003 and 2010 Bungo SSEs, indicating the high sensitivity of earthquake swarms to the migrations of slow earthquakes in this region.

The Early Chemical Characteristics of Geothermal Surface Features of Mount Lompobattang-Bawakaraeng, Gowa and Bantaeng Regency, South Sulawesi, Indonesia

The Early study of surface geothermal features characteristics, based on surface chemical characteristics fluids is compulsory for understanding the geothermal system. The geothermal area of Mount Lompobattang-Bawakaraeng is mostly located in Gowa and Bantaeng Regency, South Sulawesi and these data were taken in 2018. The stratigraphy is composed of Tertiary Volcanic Sediments and Lompobattang-Bawakaraeng Quaternary Volcanic. The geological structures consist of caldera rim on the peak of Mount Lompobatang-Bawakaraeng and the fault structure of southwest-northeast and northwest-southeast which controls the appearance of geothermal manifestations on the surface. The active thermal manifestations are only warm springs, i.e., Batu Belerang, Pencong, and Parangloe warm springs. Batu Belerang warm spring is situated at an altitude of around 1400 masl, while Pencong and Parangloe warm springs are about 24 km from Batu Belerang warm springs with a lower altitude of around 168 masl. The temperature of the warm springs is around 31- 49.2 °C. There is one inactive surface geothermal manifestation, i.e., the Cold Acid Crater Lake Blue Luraya (Danau Biru Luraya) at the elevation of 1561 masl, the water temperature of 17 °C. The result of water analysis shows that warm springs Pencong and Parangloe have more dominant HCO3. The Batu Belerang and the Cold Acid Crater Lake Blue Luraya (Danau Biru luraya) are more dominated by SO4. In the triangular diagram that compares the relative concentrations of Na, K, Mg shows that the Pencong group (Pencong and Parangloe warm springs) is plotted in the lower boundary zone of partial equilibrium, while Lompobattang group (Batu Belerang warm springs and Cold Acid Crater Lake Blue Luraya (Danau Biru Luraya) is plotted in the corner of Mg (immature waters zone). The temperature of the system is probably only estimated at the shallow part of the system by SiO2 geothermometer about 125 °C and the Batu Belerang could be more than 125 °C.

Multilayer feature fusion and saliency-attention object tracking

Most of the existing Siamese network-based trackers achieve the similarity matching problem through the cross-correlation of convolutional features between the template branch and the search branch. However, the method of using the overall feature of the target as the convolution kernel to cross-correlate with the search area contains a lot of background information, which will adversely affect the tracking. To solve this problem, we propose a feature fusion and saliency-attention Siamese network (MSSiamCAR) for object tracking, adopting a part-based tracking strategy to track discriminative local salient regions in objects. This algorithm uses the ResNet-50 network to extract the target features. To solve the loss of the shallow part of the target due to the deepening of the network, a multilayer feature is proposed. The fusion module enhances the feature extraction ability of the network for the target. Second, a saliency capture module is proposed to obtain the local saliency of the target. These saliency are robust to interference factors. The saliency interaction module is designed, and the graph attention mechanism is used to establish an effective connection between the saliency, and the target feature information is propagated to the search feature so that the tracker has more discriminative ability to the target feature. Finally, the region proposal network is used to perform operations, such as classification, regression, and centrality calculation. Experiments on challenging benchmarks, including OTB-100, VOT2018, large-scale single object tracking (LaSOT), generic object tracking-10k (GOT-10k), and unmanned aerial vehicles 123 (UAV123), demonstrate that our proposed tracker performs favorably against state-of-the-art trackers.

Seismicity Pattern of the Great Sumatran Fault System from Hypocenter Relocation of Regional Seismic Network

The seismicity pattern along the Great Sumatran Fault (GSF) was analyzed during April 2009 - December 2017 period with magnitude of >3.0 and depth of < 30 km. Of 752 preliminary absolute locations, 695 were successfully relocated using double-difference method to provide an improved view of seismicity, sharpening locations and interpretations of seismogenic features throughout the region. The relocation results depict a pattern of significant increase on small to intermediate earthquakes occurring in a shallow part of northern Sumatra, i.e. the Aceh and Seulimeum segments, as well as in central Sumatra, i.e. the Toru and Barumun. This increase was interpreted due to indications of creeping that reduce or prevent stress build-up on these segments. Meanwhile, few segments, i.e. the Tripa segment in the northern part, then Suliti and Siulak segments in the central part, and Manna segment in the southern part of Sumatra show the least activities over the period. These segments were identified as lock asperity, which caused accumulating stress that could be released as an earthquake. The behaviour of these locking segments can be related to the seismic gap along the GSF which has not experienced major earthquakes (M>7) since 2000, making the densely populated area around these segments potentially have a great seismic hazard in the future.