pure and applied geophysics最新文献

{"title":"Elastic Impedance Reconstruction Using Compound First- and Second-Order Total Variation Regularization","authors":"Kasra Nazmehr,&nbsp;Mohammad Ali Riahi,&nbsp;Amir Jamasb","doi":"10.1007/s00024-024-03629-3","DOIUrl":"10.1007/s00024-024-03629-3","url":null,"abstract":"<div><p>This study introduces a novel compound regularization technique for Elastic Impedance (EI) inversion that combines Total Variation (TV1) and Total Variation of the second-order (TV2) regularizations. This method leverages the Split-Bregman algorithm to effectively address the staircase effect, a common limitation of using TV1 regularization alone. The proposed approach enforces smoothness (TV1) and improved edge preservation (TV2) in the reconstructed EI models, leading to more accurate representations. The efficacy of this method is demonstrated by applying it to two geologically relevant elastic models: the Marmousi model (complex but synthetic) and seismic field data from the Gulf of Mexico. Numerical tests were conducted using realistic noise levels, and the results confirmed the proposed method’s ability to reconstruct detailed and accurate EI models for both models, highlighting its generalizability to diverse geological scenarios. Unlike the simpler TV1 and TV2 regularizations, our combined approach adeptly handles complex models featuring both smooth and abrupt transitions, though its performance can vary across different geological scenarios. This method provides a promising framework for improved EI reconstruction in diverse geological settings.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 1","pages":"125 - 139"},"PeriodicalIF":1.9,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143481199","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":"Combining Envelope Inversion and Full Waveform Inversion for Velocity Model Building Using OBN Data","authors":"Min Ouyang,&nbsp;Wenrui Ye,&nbsp;Dun Deng,&nbsp;Xingguo Huang,&nbsp;Xiaodong Luo","doi":"10.1007/s00024-024-03649-z","DOIUrl":"10.1007/s00024-024-03649-z","url":null,"abstract":"<div><p>Oil and gas constitute a significant part of marine resources, whose exploration and production routinely rely on geophysical seismic data to improve existing databases. Traditional seismic datasets have suffered from extensive ambiguity due to the combined effects of thermal fluids, fractures, shallow velocity anomalies, and mid-deep layer bottom structure. Actual situation displays that despite several previous reprocessing efforts, the quality of seismic data in some ambiguous areas has only been partially improved, while the resolution issues remain unresolved. Given the poor seismic imaging quality and extraordinarily low signal-to-noise ratio data, it is challenging to determine the accurate structural features. To tackle this challenge, we combine the analysis of wavefield attenuation characteristics and high-precision velocity modeling as well as inversion methods to depict the subsurface areas. We aim at provide a validate high-quality seismic data processing and inversion method to determine an accurate velocity model to support the interpretation of actual geological data. We introduce the low-frequency reconstructed envelope inversion and investigate GPU/CPU paralleled full waveform inversion (FWI) method. We demonstrate the efficacy of our method by using both synthetic data and field data from a certain sea area in China. Numerical results indicate that a combination of low-frequency reconstructed envelope inversion and full waveform inversion can effectively improve the accuracy of the existing velocity data for more than 25%.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 1","pages":"141 - 165"},"PeriodicalIF":1.9,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143481200","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":"Spatio-Temporal Changes in Cold Wave Characteristics Over the Diverse Meteorological Sub-Divisions of India","authors":"Saumya Singh,&nbsp;R. K. Mall,&nbsp;Pradip Kumar Gautam","doi":"10.1007/s00024-024-03647-1","DOIUrl":"10.1007/s00024-024-03647-1","url":null,"abstract":"<div><p>Cold wave (CW) and Severe Cold wave (SCW) prevail over India as a seasonal episode during winter season. The present study analyzes the changing spatio-temporal characteristics and trends of cold waves over India's meteorological subdivisions from 1951 to 2021 (Dec–Feb). It uses minimum temperature data obtained from the India Meteorological Department (IMD) at a spatial resolution of 0.5° × 0.5°. A declining trend in both CW and SCW days is found with a decrease of − 0.29 days/decade in CW days and 0.02 days/decade in SCW days. The study also explored the trend of spells of three, five and seven days of CW and SCW and found a significantly decreasing trend of − 0.02 days/decade and − 0.05 days/decade in 3 and 5-day SCW spell respectively. A consistent significant increase of 0.027 °C/decade in minimum temperature post 1980s is also reported in the study with a simultaneous decrease in cold wave. While the northwestern and northern meteorological subdivision record highest CW and SCW spells, a declining trend is reported in these regions, highest being in West Rajasthan (− 1.3 days/decade) and Punjab (− 1.3 days/decade). A significant increasing trend has been observed in CW, SCW days/spells in the eastern, eastern coastal and southern subdivisions such as Bihar (0.16 days/decade), Jharkhand (0.05 days/decade) and Odisha (0.2 days/decade). Overall, the study reports a decline in cold waves and identifies new cold wave-prone regions in the country. The study also highlights the emerging severe impact on agriculture sector in the scenario of declining cold extremes over major wheat producing belts.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 2","pages":"859 - 875"},"PeriodicalIF":1.9,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638260","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":"Creep Behavior of Mélange Rocks and the Hardening-Damage Nonlinear Elastic-Viscous Model","authors":"Zaobao Liu,&nbsp;Hyonsong Oh,&nbsp;Ming Wu,&nbsp;Kisong Yu,&nbsp;Hongyuan Zhou","doi":"10.1007/s00024-024-03635-5","DOIUrl":"10.1007/s00024-024-03635-5","url":null,"abstract":"<div><p>This study aims to establish a mode for representing the creep behavior of mélange rock in various underground geoengineering projects. We conducted multi-stage triaxial compression creep tests to investigate key aspects of creep behavior, including the evolution of the creep rate, cumulative creep strain, and long-term strength. The results indicate that the creep rate curves exhibit a trend resembling a parabolic function, approaching their minimum values as they converge to long-term strengths. The cumulative creep strain to total strain ratio ranges from 0.245 to 0.2917 across different confining pressures (5, 10, 15, and 20 MPa). Additionally, long-term strengths extracted from isochronous curves of dimensionless variables are consistently aligned with the maximum creep strain to elastic strain ratio, falling within a stress ratio range of 0.75 to 0.82. To model this behavior, we propose a Hardening-Damage Nonlinear Elastic-Viscous framework comprising two nonlinear viscous elements and an elastic element configured in a serial link structure, following the principles of Maxwell’s model. The parameters and coefficients of this model were evaluated against the multi-stage creep test results, confirming its effectiveness in replicating the creep behavior of mélange rock. The proposed model, characterized by a limited number of coefficients related to material properties, simplifies the analysis. Ultimately, this work aids in evaluating the stability of deep-underground tunnel surrounding mélange rock masses.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 2","pages":"587 - 608"},"PeriodicalIF":1.9,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638213","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":"Effects of Hot Plumes and Slab Rheology on the Bending of the Philippine Sea Slab at Shallow Depths Beneath the Kyushu Region, Southwest Japan","authors":"Natsuki Kozai,&nbsp;Nobuaki Suenaga,&nbsp;Shoichi Yoshioka,&nbsp;Vlad Constantin Manea","doi":"10.1007/s00024-024-03616-8","DOIUrl":"10.1007/s00024-024-03616-8","url":null,"abstract":"<div><p>The Philippine Sea (PHS) plate is currently subducting beneath the Kyushu region in southwestern Japan and exhibits a steep dip angle at depths of approximately 70–100 km. It has been suggested that the increase in the dip angle may be attributed to a hot plume, which was purportedly present in the northwestern part of Kyushu approximately 10–6 Ma, flowing southeastward toward southern Kyushu and causing steep shallow bending of the PHS plate. Using numerical simulations, this study quantitatively evaluates the impact of an upwelling hot plume from the northwestern part of Kyushu on the abrupt bending of the PHS plate at shallow depths. We use a time-dependent two-dimensional thermal convection model that incorporates the subduction history of the PHS plate along a vertical plane passing through a hot plume from northwestern Kyushu to the Nankai Trough. Numerical simulations were conducted to investigate the behavior of a slab when colliding with an upwelling hot plume, considering different values of slab viscosity. The results demonstrate that when a hot plume impacts a slab with a viscosity lower than that of a normal strong slab, the bending of the slab is reproduced at a depth of approximately 100 km, which is consistent with the observed PHS slab bending at depths of 70–100 km.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 4","pages":"1861 - 1888"},"PeriodicalIF":1.9,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00024-024-03616-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143883592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probing the Complex Interaction of Makran Subduction Zone with Regional Tectonic Features: Insights from Gravity and Seismic Source Parameters","authors":"Raja Adnan Habib,&nbsp;Muhammad Tahir Iqbal,&nbsp;Mohammad Salam,&nbsp;Mohammad Tahir,&nbsp;Javed Iqbal,&nbsp;Talat Iqbal","doi":"10.1007/s00024-024-03631-9","DOIUrl":"10.1007/s00024-024-03631-9","url":null,"abstract":"<div><p>Unraveling the intricate tectonic framework of the Makran subduction zone is essential for enhancing our understanding of seismic risks and developing effective mitigation strategies. This study delves into this complexity by analyzing gravity data and stress states derived from earthquake focal mechanisms. In this endeavor, the distribution and nature of seismic activity were compared with lateral gravity variations observed through vertical changes at the near-surface, intermediate, and regional levels. This analysis revealed a strong correlation between abrupt gravity changes and earthquake occurrences. This study reveals contrasting stress regimes across subduction zones and associated tectonic elements. Along the deformation front of the subduction zone, predominantly north−south compression occurred, and greater coupling in the eastern part was inferred based on gravity data. Northward, an anti-clockwise rotation of the stress axis is consistent with regional tectonics and deep structures within the Afghan Block, possibly influenced by the Chaman Transform Boundary to the east. The same northeast−southwest trend is followed by a deep normal faulting band related to the flexure of the subducted Arabian plate, which exhibits complex behavior, particularly in the west, where it seems to detach from the eastern part and interact with the deep root of the Sistan Suture. The same interaction may be responsible for the comparatively higher seismic activity in the western part of the flexural structure. The presence of a low-density zone below 100 km depth implies that two deep earthquakes occurring underneath the Chaghi volcanic arc discordant with the general trend of tectonic features and the stress axis may be associated to contortion in the subducting Arabian Plate under the effect of deep root’s Indo-Eurasian plate boundary.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 1","pages":"55 - 77"},"PeriodicalIF":1.9,"publicationDate":"2024-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143481154","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":"Aircraft Studies of Horizontal and Inclined Spectra of Wind Velocity Fluctuations in the Stably-Stratified Troposphere","authors":"Igor Chunchuzov,&nbsp;Oleg Popov,&nbsp;Sergey Kulichkov,&nbsp;Otto Chkhetiani","doi":"10.1007/s00024-024-03637-3","DOIUrl":"10.1007/s00024-024-03637-3","url":null,"abstract":"<div><p>In this paper, we study tropospheric wind velocity fluctuation spectra measured both along horizontal aircraft tracks over Greenland and along inclined aircraft tracks during their ascents and descents. This study is done based on the analysis of the global and long-term high-resolution dataset of meteorological parameters measured by civil aircrafts. The transition from the Nastrom-Gage spectrum with a slope of -5/3 in the horizontal scale-range of 6–200 km to a steeper part of the spectrum at shorter scales is analyzed. Based on the results of wind measurements along 82 inclined trajectories of airplanes during their ascent and descent in the troposphere, the vertical wave number spectra of wind velocity fluctuations measured along these trajectories as a function of height (hereinafter referred to as inclined spectra) were obtained. From the obtained horizontal and inclined spectra of the wind velocity fluctuations their anisotropy (the ratio of horizontal-to-vertical scale) is estimated. The obtained spectra are interpreted using models of 3-D and 1-D (horizontal and vertical) wavenumber spectra of the wind velocity fluctuations. The tropospheric vertical wave number spectra of anisotropic wind velocity fluctuations obtained from the aircraft measurements during ascents and descents (altitudes 5–10 km) are compared to the vertical wave number spectra of the wind velocity fluctuations in the stratosphere and mesosphere retrieved from the infrasound signals generated by ground-based explosions and volcanic eruptions. The general physical mechanism of formation of the fine layered structure of wind velocity for both the stably-stratified layers of the troposphere and the stratosphere-mesosphere is discussed.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 1","pages":"235 - 254"},"PeriodicalIF":1.9,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143481230","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":"Research on Microseismic Periodic Noise Suppression Method Based on Long Short-Term Memory Network","authors":"Xulin Wang,&nbsp;Minghui Lv","doi":"10.1007/s00024-024-03643-5","DOIUrl":"10.1007/s00024-024-03643-5","url":null,"abstract":"<div><p>The signal-to-noise ratio of ground-truth microseismic data is relatively low. Most of the current noise suppression methods are effective in dealing with random noise but neglect the periodic noise present in the microseismic data, leading to poor denoising effects. To address this issue, this paper proposes a new noise suppression method that combines short-time stationarity tests with Long Short-Term Memory (LSTM) algorithms to suppress periodic noise in microseismic data. By processing both simulated and field data and comparing the results with the traditional Variational Mode Decomposition (VMD) algorithm, the experimental results demonstrate that the method proposed in this paper can more effectively suppress periodic background noise in microseismic data, thereby enhancing the signal-to-noise ratio of the data.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 1","pages":"107 - 123"},"PeriodicalIF":1.9,"publicationDate":"2024-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143481035","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":"The Applicability of Point-Source Models in Ground-Motion Prediction","authors":"Igor A. Beresnev","doi":"10.1007/s00024-024-03646-2","DOIUrl":"10.1007/s00024-024-03646-2","url":null,"abstract":"<div><p>Point-source simulations with simple functional shapes of radiated Fourier spectra are widely used in earthquake-hazard assessments. Such an approximation is based on two physical assumptions: that (1) all near-field phenomena and (2) the wave-interference effects, caused by fault finiteness, are negligibly small (the far-field and the point-source approximations, respectively). The limits of applicability of these assumptions can be deduced from the complete theoretical description of the seismic field radiated by a fault rupture, expressed in the representation integral of elasticity. The far-field condition, deduced directly from the representation integral, is controlled by the slip and the slip rate on the fault; for a <i>M</i>_<i>w</i> 4 earthquake (<i>M</i>_<i>w</i> is the moment magnitude), it is reasonably satisfied at the distance of a few hundred meters. The point-source approximation is not satisfied even for the smallest earthquakes considered in seismic hazards: for a <i>M</i>_<i>w</i> 4 earthquake, the radiated finite-fault spectra significantly deviate from the commonly postulated omega-square shapes already at the frequencies around 1 Hz and above. The interference phenomena caused by fault finiteness act as a high-cut filter, creating the observed deficit in the high-frequency energy not accounted for by point-source spectra. To correct, the point-source models apply ad-hoc filtering, such as the kappa operator, acting as a substitute for the filtering naturally created by the fault itself. The finite-fault spectra without additional filtering can be formally explained by an equivalent point source with the kappa operator applied. The <i>κ</i> values determined from the equivalent point-source spectrum are in the same range as those empirically observed. However, if a finite-fault spectrum is interpreted as a point-source one with kappa, the values of the maximum slip velocity, an influential physical parameter of rupture, are recovered incorrectly. The kappa filtering can be fully explained by the finite-fault effects always present in all earthquakes of practical significance.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 1","pages":"45 - 53"},"PeriodicalIF":1.9,"publicationDate":"2024-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143481036","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":"Spatio-Temporal Variability of Aridity and Humidity Indices in Bačka (Serbia)","authors":"Nikola Milentijević,&nbsp;Nataša Martić-Bursać,&nbsp;Milena Gocić,&nbsp;Marko Ivanović,&nbsp;Sanja Obradović Strålman,&nbsp;Milana Pantelić,&nbsp;Dragan Milošević,&nbsp;Ljiljana Stričević","doi":"10.1007/s00024-024-03628-4","DOIUrl":"10.1007/s00024-024-03628-4","url":null,"abstract":"<div><p>This paper assessed aridity and humidity conditions in Bačka (north Serbia) in the period 1949–2018. The assessment was based on the analysis of air temperature and total precipitation from 5 meteorological stations. Spatio-temporal changes were determined based on aridity indices, statistical and interpolation procedures. The Mann–Kendall indicates no statistical significance in aridity trends at most stations. The annual value of the Lobova index indicates arid conditions. Monthly values of the De Martonne index (I_DM) do not show a statistically significant positive or negative trend, except for May, September to December. The annual values of the I_DM indicate diversity of aridity conditions with a statistically significant positive trend on annual level only at one station (Sombor). Dry and wet years are equally distributed based on Rainfall Anomaly Index (RAI). The 2010 belongs to extremely wet category while the 2000 stands out as extremely dry. Statistically significant positive aridity trend was observed for RAI on annual level for two stations (Palić and Sombor). According to interpolation technique, annual and seasonal values of the I_DM belong to humid and semi-humid conditions. The spatial variability of the RAI is between normal and slightly dry. The Lobova index shows different patterns of aridity. This study provides insight into the dynamics of aridity, and its results can be used in planning and implementing climate change adaptation measures. Since agricultural productivity is highly dependent on aridity and drought conditions, agricultural activities face numerous challenges. Therefore, the presented results can provide a solid basis for designing and implementing adaptation strategies and interventions on a regional scale in order to mitigate the impacts of climate change and aridity on agricultural production in the studied region.</p></div>","PeriodicalId":21078,"journal":{"name":"pure and applied geophysics","volume":"182 2","pages":"705 - 728"},"PeriodicalIF":1.9,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143638499","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}