Acta Geophysica最新文献

{"title":"Integrated geophysical model approach for Nazca Plate subduction in Ecuador","authors":"Carlos Araque-Pérez, Janckarlos Reyes-Lucero, Inírida Rodriguez-Millan","doi":"10.1007/s11600-024-01440-1","DOIUrl":"https://doi.org/10.1007/s11600-024-01440-1","url":null,"abstract":"<p>This research addresses 2D models of the Nazca-South America subduction zone off the coast of Ecuador using the European Improved Gravity Model of the Earth by New Techniques (EIGEN-6C4), the Earth Magnetic Anomaly Grid with a 2-arc-minute resolution model (EMAG2 V3), and the seismic catalog from the Ecuadorian Geophysical Institute of the National Polytechnic School (IGEPN). Since the Upper Cretaceous, the region has experienced several geomorphological and structural alterations within the oceanic plate (Carnegie Ridge and Grijalva Fault Zone) and continental plate (North Andean Block and South American Plate). These changes result from a complex geodynamic history involving ancient subduction zones, accretions, and roll-back stages of allochthonous oceanic terrains and the autochthonous continental coast. To ensure the accuracy of the selected gravimetric model, the EIGEN-6C4 model was statistically compared with the pure-satellite gravimetric model, GO-CONS-TIM-R6e. Several geophysical analyses, such as terrain correction, geostatistical analysis, clustering, and power spectrum, were performed to gain valuable insights into gravity and magnetic sources. Then, these results were incorporated as constraints into the forward modeling procedure, which was adjusted to hypocenters, generating four subduction profiles that were then refined by an inversion method. The 0°S profile shows a subduction angle of 15° and escalates to 35° beyond 55 km depth, with the oceanic crust thickening at the Carnegie Ridge up to 18 km. The 1°S profile displayed two inflection points implying changes in the dip angle: a transition from 14° to 7° dip angle, supporting a change to low-angle subduction, and a transition from 7° to 40°, suggesting normal subduction beneath the Andean Cordillera. In the 2°S profile, the subduction initiates with a 15° angle beneath the continental plate extending to 60 km beneath the Manabi Basin, then potentially increases to 30° beyond 120 km depth. The 3°S profile beneath the Andes revealed a stable subduction zone with a constant dip angle of 14° and flat-slab subduction. Creating a three-dimensional interpolated model between the modeled profiles as a sketch of the angle variation of the subducted slab in the Equatorian region. The small root-mean-square error indicates that the models adequately represent the data. These models provide valuable observations of the geometric variations of the subducting plate, highlighting the impact of heterogeneous physiographic elements within the oceanic crust and the presence of an ancient subduction slab derived from the Farallon Plate.</p>","PeriodicalId":6988,"journal":{"name":"Acta Geophysica","volume":"15 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142254932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A study on geoelectrical recognition model of seawater/freshwater interface based on convolutional neural network: an application in sand tank experiments","authors":"Jun Ma, Lusi Wei, Jia Xiong, Zhifang Zhou, Shumei Zhu","doi":"10.1007/s11600-024-01441-0","DOIUrl":"https://doi.org/10.1007/s11600-024-01441-0","url":null,"abstract":"<p>Seawater intrusion is a global environmental issue, and seawater intrusion monitoring requires a multidisciplinary approach to improve accuracy. Simplified seawater/freshwater interface models for coastal aquifers are generally divided into two types: abrupt interface models and wedge-shaped interface models. Electrical resistivity tomography (ERT) is the visualization of subsurface resistivity distributions in 2D or 3D and has been widely used in seawater intrusion monitoring. This paper presents a geoelectrical recognition model for classifying simplified seawater/freshwater interface types based on a convolutional neural network (CNN). The CNN structure is composed of three convolutional layers, three max pooling layers, two fully connected layers, and one Softmax layer. A total of 686 samples were combined for model training, and obtained 0.9581 for the average accuracy (ACU) and 1.3500 for the average cross-entropy loss (CEL). Sand tank experiments were carried out to simulate the process of seawater intrusion caused by a rise in the water level of sea water rise or a decrease in the water level of fresh water, the ERT method was used to monitor the resistivity of the aquifer during the experiments, and the fully trained CNN model was used to classify the interface types. According to the output data, the probability of observing the wedge-shaped interfaces during the experiments at 300 and 345 min were 98.85% and 99.89%, while the probability of observing the abrupt interfaces were 1.15% and 0.11%. The results showed that the ERT method offers a fast and nondestructive approach for monitoring seawater intrusion, and accurate recognition results of interface types were obtained using a well-trained recognition model in the laboratory experiments.</p>","PeriodicalId":6988,"journal":{"name":"Acta Geophysica","volume":"47 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142254931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial variation, sources, and trajectory of black carbon in the South Sumatra Region of Indonesia using MERRA-2 reanalysis data","authors":"Muhammad Rendana, Novia Novia, Tuti Indah Sari, Maulana Yusuf, Idarwati","doi":"10.1007/s11600-024-01444-x","DOIUrl":"https://doi.org/10.1007/s11600-024-01444-x","url":null,"abstract":"<p>A high temperature and lack of rainfall in the South Sumatra Region during the dry season of 2019 led to an increase in intense land fires that were attributed to biomass burning and the pyrogenic combustion process. This study tried to analyze the spatiotemporal distributions of atmospheric BC (black carbon) over the South Sumatra Region during 2016–2019 land fire events using the MERRA-2 satellite images. The spatial analysis was applied to estimate the increment in black carbon concentrations during land fire episodes. Some meteorological conditions that affect black carbon diffusion and transport over the study area are explained using a backward trajectory analysis. The results exhibited that the black carbon masses mostly came from local and long-range transports (from eastern to western) over the study area. A significant percentage increment of black carbon concentration during 2016–2019 was observed at around 139%. The highest black carbon concentration recorded in October 2019 was 3.96 × 10⁻⁶ kg/m², as hotspots were still abundant, especially on the eastern side of the study area. The black carbon trend was strongly related to total hotspots and burned areas. As a whole, this finding could be beneficial for mitigating black carbon pollution due to land fires by implementing geospatial technology for rapid monitoring of air pollution in vast areas.</p>","PeriodicalId":6988,"journal":{"name":"Acta Geophysica","volume":"42 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142254934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"3D UHR seismic and back-scattering analysis for seabed and ultra-shallow subsurface classification","authors":"Jiho Ha, Jungkyun Shin, Kyoungmin Lim, In-Kwon Um, Boyeon Yi","doi":"10.1007/s11600-024-01423-2","DOIUrl":"https://doi.org/10.1007/s11600-024-01423-2","url":null,"abstract":"<p>Recently, the seabed classification method based on back-scattering data of multi-beam echo-sounder (MBES) is widely used to analyze the distribution of seabed sediment. Although various analysis methods for seabed classification using multi-spectral MBES have been developed, they are limited in securing penetration depth to consider the characteristics of the shallow subsurface structure. In this study, the seabed and ultra-shallow subsurface classification was performed by comparative analysis of box corer sampling, back-scattering, and 2D/3D ultra-high-resolution (UHR) seismic data obtained from Yeongil Bay, South Korea. We proposed a process for seismic ultra-shallow subsurface classification by the segmentation of the primary seabed reflection wavelet and the amplitude analysis. The seabed-reflected amplitude and back-scattering intensity showed similar mapping trends in the relatively homogeneous and thick surface sediment. On the other hand, it was confirmed that back-scattering data and seabed-reflected amplitude show different patterns when the subsurface structure is related to the seabed surface. It is presumed that because seismic data containing relatively low-frequency components have a deeper penetration depth than MBES, they contain more characteristics of the ultra-shallow subsurface than back-scattering data. These were determined that back-scattering has advantages in representing acoustic anomaly distribution by surface sediment type, and seabed-reflected amplitude is advantageous for representing sediment type by ultra-shallow subsurface. In particular, these results were well shown when the surface sediment thinly covered the rocky bottom. Therefore, it is necessary not only to analyze the back-scattering of MBES but also the ultra-shallow subsurface features through seismic data for valid seabed classification.</p>","PeriodicalId":6988,"journal":{"name":"Acta Geophysica","volume":"29 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pore pressure estimation of the calcareous formations in the Middle Magdalena Valley Basin, Colombia","authors":"Melina Rivera, Luis Alfredo Montes, Luis Antonio Castillo","doi":"10.1007/s11600-024-01357-9","DOIUrl":"https://doi.org/10.1007/s11600-024-01357-9","url":null,"abstract":"<p>The reliable prediction of pore pressure is essential for petroleum engineering in its different stages, with the Eaton and Bowers' methods being the most used for this purpose. However, their application in carbonate rocks still needs to be improved because carbonates do not compact uniformly with depth, as shale does. This research calculated the pore pressure using the Eaton, Bowers, and Weakley methods and well logs of a carbonate formation and found that the Weakley's approach predicts pressure more accurately. The method presented uses an acoustic impedance equation derived from the Bowers' method, whose parameters were calibrated with the Weakley's pore pressure profile. The pore pressure estimated near the borehole, via the acoustic impedance provided by the pre-stack inversion, is very close to that observed during drilling, which indicates a reliable prediction. The method was applied to a seismic line and well logs in the Middle Magdalena Valley Basin—Colombia, where the overpressured well Lizama 158 caused a significant environmental disaster in 2018. The obtained subsurface pore pressure distribution is reliable, matches overpressure in calcareous rocks near the well, and estimates anomalous pressure in zones distant from the well.</p>","PeriodicalId":6988,"journal":{"name":"Acta Geophysica","volume":"12 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185621","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of fault-karst reservoirs based on deep learning and attribute fusion","authors":"Zhipeng Gui, Junhua Zhang, Yintao Zhang, Chong Sun","doi":"10.1007/s11600-024-01420-5","DOIUrl":"https://doi.org/10.1007/s11600-024-01420-5","url":null,"abstract":"<p>The identification of fault-karst reservoir is crucial for the exploration and development of fault-controlled oil and gas reservoirs. Traditional methods primarily rely on well logging and seismic attribute analysis for karst cave identification. However, these methods often lack the resolution needed to meet practical demands. Deep learning methods offer promising solutions by effectively overcoming the complex response characteristics of seismic wave fields, owing to their high learning capabilities. Therefore, this research proposes a method for fault-karst reservoir identification. Initially, a comparative analysis between the improved U-Net++ network and traditional deep convolutional networks is conducted to select appropriate training parameters for separate training of karst caves and faults. Subsequently, the trained models are applied to actual seismic data to predict karst caves and faults within the research area, followed by attribute fusion to acquire data on fault-karst reservoirs. The results indicate that: (1) The proposed method effectively identifies karst caves and faults, outperforming traditional seismic attribute and coherence methods in terms of identification accuracy, and slightly surpassing U-Net and FCN; (2) The fusion of predicted karst caves and faults yields clear delineation of the relationship between top karst caves and bottom fractures within the research area. In summary, the proposed method for fault-karst reservoirs identification and characterization provides valuable insights for the exploration and development of fault-controlled oil and gas reservoirs in the region.</p>","PeriodicalId":6988,"journal":{"name":"Acta Geophysica","volume":"9 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Increase in porosity and permeability resolution for thin-bedded Miocene formation in Carpathian Foredeep using different clustering methods","authors":"Sebastian Waszkiewicz, Paulina Krakowska-Madejska","doi":"10.1007/s11600-024-01409-0","DOIUrl":"https://doi.org/10.1007/s11600-024-01409-0","url":null,"abstract":"<p>The accurate interpretation of well-logging data is a crucial stage in the exploration of gas- and oil-bearing reservoirs. Geological formations, such as the Miocene deposits, present many challenges related to thin layers, whose thickness is often less than the measurement resolution. This research emphasizes the potential of utilizing electrofacies in such challenging environments. The application of electrofacies not only allows for the grouping of intervals with similar physical characteristics but can also be useful for estimating porosity and permeability parameters. For this purpose, various clustering methods were tested, including the 2D indexed and probabilized self-organizing map (IPSOM) method with and without supervision. Subsequently, the usefulness of the obtained results to improve the estimation of porosity and permeability parameters with the help of artificial neural networks was verified. As a result of the conducted analyses, significantly better results were obtained compared to classical petrophysical interpretation. The calculated porosity and permeability parameters were characterized by much greater variability and alignment with laboratory measurements on porosity and permeability. The best results were obtained for the IPSOM method, but the other methods did not differ significantly. In conclusion, the studies have shown a positive result of applying clustering methods, including the IPSOM method, to improve the estimation of permeability and porosity parameters in complicated, thinly-layered formations.</p>","PeriodicalId":6988,"journal":{"name":"Acta Geophysica","volume":"30 15 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fine structures of a solar type III radio bursts observed with LOFAR","authors":"Bartosz Dabrowski, Aleksandra Wolowska, Christian Vocks, Jasmina Magdalenić, Peijin Zhang, Pawel Flisek, Malte Bröse, Diana E. Morosan, Andrzej Krankowski, Adam Fron, Gottfried Mann, Pietro Zucca, Mario Bisi, Richard Fallows, Peter Gallagher, Christophe Marqué, Barbara Matyjasiak, Hanna Rothkaehl","doi":"10.1007/s11600-024-01421-4","DOIUrl":"https://doi.org/10.1007/s11600-024-01421-4","url":null,"abstract":"<p>We present spectral and imaging LOFAR (LOw-Frequency ARray) observations in the 20 – 40 MHz range of solar radio bursts fine structures, such as flag-like, sail-like, and dot-like that appeared on 8 April 2019. These structures were associated with type III solar radio bursts that occurred in the 40 – 80 MHz band. The mean duration and spectral widths of the fine structures range from 1.0 to 3.4 s and from 0.3 to 0.9 MHz, respectively. Additionally, we investigated the radio images of eight fine structures – two flags, two sails and four dots. This allowed us to determine their emission source sizes, which ranged from 240 to 392 arcmin<span>({}^2)</span>, and their frequencies from 25.58 to 39.25 MHz as well as their location. They occurred on the east side of the Sun and were most likely associated with an emerging active region NOAA AR 12738, where a weak B1.7 flare was observed.</p>","PeriodicalId":6988,"journal":{"name":"Acta Geophysica","volume":"105 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142185656","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-term Aftershock Properties of the Catastrophic 6 February 2023 Kahramanmaraş (Türkiye) Earthquake Sequence","authors":"Onur Tan","doi":"10.1007/s11600-024-01419-y","DOIUrl":"https://doi.org/10.1007/s11600-024-01419-y","url":null,"abstract":"","PeriodicalId":6988,"journal":{"name":"Acta Geophysica","volume":"4 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141925881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative assessment of gridded soil moisture data products (2000–2019) for drought detection: A study over Indian region","authors":"Prabir Kumar Das, Subhadip Sarkar, Rituparna Das, Dipanwita Dutta, Suparn Pathak","doi":"10.1007/s11600-024-01418-z","DOIUrl":"https://doi.org/10.1007/s11600-024-01418-z","url":null,"abstract":"<p>The soil moisture drought is an intermediate event between meteorological and agricultural droughts. The information on soil moisture droughts provides an indication about the resilience of the agricultural systems. In the present study, a comparative assessment of the monthly soil moisture gridded data products of Modern Era Retrospective analysis for Research and Applications, i.e., MERRA-2 (0.5° × 0.5°), Climate Prediction Center, i.e., CPC (0.5° × 0.5°), Global Land Data Assimilation System, i.e., GLDAS (0.25° × 0.25°), and European Space Agency Climate Change Initiative, i.e., ESA CCI (0.25° × 0.25°) during 2000 to 2019 was carried out in terms of drought occurrence and severity. The long-term soil moisture information was transformed into standardized soil moisture index (SSMI) using nonparametric distribution, followed by computation of drought duration and magnitude using thresholding approach. The long-term trends of drought parameters, i.e., duration and magnitude, were extracted using Mann–Kendall test and Sen’s Slope method, respectively. It was interesting to note that irrespective of zones, the SSMI derived from MERRA-2 and CPC have maximum coherence in terms of both pattern and intensity, followed by GLDAS. The trends of drought duration and magnitude differ based on the data products; however, frequent droughts were observed over parts of peninsular India and Indo-Gangetic plains irrespective of data products. The increased drought duration and magnitude were found over major parts of central and peninsular India, western parts of north-eastern India and eastern parts of north-western India.</p>","PeriodicalId":6988,"journal":{"name":"Acta Geophysica","volume":"76 1","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}