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Characteristics of the Tropical Tropopause over Chennai (13.0° N, 80.06° E) in the Northeast Monsoon Region 东北季风区钦奈(北纬 13.0°,东经 80.06°)上空的热带热带顶的特征
IF 1.9 4区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2024-06-17 DOI: 10.1007/s00024-024-03519-8
Purushotham Pooja, Sanjay Kumar Mehta, Sachin Philip Kakkanattu, K. B. Betsy, C. J. Seetha, P. P. Musaid

Knowledge of the tracer characteristics, such as water vapor and ozone in the tropical tropopause layer (TTL), is vital in quantifying the radiation budget and critical to understanding the exchange processes between the troposphere and stratosphere. In this study, we have characterized the tropical tropopause parameters such as the cold point tropopause (CPT) height (CPT-H) and temperature (CPT-T), convective tropopause (COT) height (COT-H) and temperature (COT-T), and the tropical tropopause layer (TTL) using radiosonde observations during 2014–2019 over Chennai (13.0° N, 80.06° E) located in the northeast (NE) monsoon region. The water vapor and ozone data from the microwave limb sounder (MLS) simultaneous to the radiosonde observations are also utilized to understand their roles on the CPT variations for different convective conditions obtained from Infrared brightness temperature (IRBT) data. CPT over Chennai becomes higher (17.6 ± 0.3 km) and colder (189.7 ± 0.9 K) during the winter season and lower (16.6 ± 0.2 km) and warmer (192.1 ± 1.0 K) during the summer monsoon season, however, not in the same month. The water vapor (CPT-W) and ozone (CPT-O) mixing ratios at CPT are found to be lower (~ 70 ± 1.4 ppmv and 3.1 ± 0.4 ppmv) during the winter season and higher (153 ± 4.2 ppbv and 4.8 ± 0.6 ppmv) during summer monsoon season. COT, however, becomes lower (12.4 ± 0.3 km) and higher (13.3 ± 0.3 km) during pre-monsoon and summer monsoon seasons, respectively. The TTL thickness is lesser (3.5 ± 0.6 km) during the winter and greater (4.8 ± 0.8 km) during the summer monsoon seasons. Over Chennai, the seasonal variation of the upper troposphere and lower stratospheric temperature, water vapor, and ozone anomalies are in phase. We have categorized tropical convections as non-penetrative and penetrative using IRBT data. It is observed that the TTL temperature warms with the increasing strength of the non-penetrative convections and cools for the penetrative convection.

了解热带对流层顶层(TTL)的水汽和臭氧等示踪特征对于量化辐射预算至关重要,对于了解对流层和平流层之间的交换过程也至关重要。在这项研究中,我们利用位于东北季风区的钦奈(北纬 13.0°,东经 80.06°)上空 2014-2019 年期间的无线电探空仪观测数据,对热带对流层顶参数,如冷点对流层顶(CPT)高度(CPT-H)和温度(CPT-T)、对流对流层顶(COT)高度(COT-H)和温度(COT-T)以及热带对流层顶层(TTL)进行了描述。此外,还利用与无线电探空仪观测同步进行的微波测边仪(MLS)的水汽和臭氧数据,以了解它们对红外亮度温度(IRBT)数据所获得的不同对流条件下 CPT 变化的影响。钦奈上空的 CPT 在冬季变得更高(17.6 ± 0.3 千米)、更冷(189.7 ± 0.9 千帕),在夏季季风季节变得更低(16.6 ± 0.2 千米)、更热(192.1 ± 1.0 千帕),但不是在同一个月份。发现 CPT 的水汽(CPT-W)和臭氧(CPT-O)混合比在冬季较低(~ 70 ± 1.4 ppmv 和 3.1 ± 0.4 ppmv),而在夏季季风季节较高(153 ± 4.2 ppbv 和 4.8 ± 0.6 ppmv)。然而,在季风前和夏季季风季节,COT 分别变低(12.4 ± 0.3 千米)和变高(13.3 ± 0.3 千米)。TTL 厚度在冬季较小(3.5 ± 0.6 千米),在夏季季风季节较大(4.8 ± 0.8 千米)。在钦奈上空,对流层上部和平流层下部的温度、水汽和臭氧异常的季节变化是同步的。我们利用 IRBT 数据将热带对流分为非穿透型和穿透型。据观察,对流层温度随着非穿透性对流强度的增加而升高,而穿透性对流的温度则降低。
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引用次数: 0
Compact Beta-Gamma Radioxenon Detection System with Improved Energy Resolution Using PIPS Detector 利用 PIPS 探测器提高能量分辨率的紧凑型β-γ 射线氙探测系统
IF 2 4区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2024-06-17 DOI: 10.1007/s00024-024-03487-z
Sepideh Alsadat Azimi, Hossein Afarideh, Jong-Seo Chai

The monitoring of four radioxenon isotopes stands out as a key technology employed in detecting underground nuclear tests. In support of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), we develop and calibrate a novel radioxenon detection system based on beta-gamma coincidence, utilizing NaI(Tl) and silicon detectors for gamma and beta radiation detection. To assess its performance, the prototype detection system undergoes rigorous testing with 222Rn and 131mXe sources. A 166mHo source is employed for energy calibration and performance evaluation of the silicon detector. In this study, we aim to investigate the utility of these materials and methods for a radioxenon detection system to achieve higher energy resolution while minimizing memory effects compared to conventional systems that employed plastic scintillator detectors. Our results demonstrate a significantly improved energy resolution of 7.8% (factor of ~ 3 × compared to plastic detectors) at the 129 keV conversion electron peak of 131mXe. The improved system is a foundation for the development of operational systems with optimized geometry for the discrimination of radioxenon isotopes.

监测四种放射性氙同位素是探测地下核试验的一项关键技术。为支持《全面禁止核试验条约》(CTBT),我们利用 NaI(Tl)和硅探测器进行伽马和贝塔辐射探测,开发并校准了基于贝塔-伽马重合的新型放射性氙探测系统。为了评估其性能,原型检测系统使用 222Rn 和 131mXe 源进行了严格的测试。166mHo 源用于硅探测器的能量校准和性能评估。与使用塑料闪烁体探测器的传统系统相比,本研究旨在研究这些材料和方法在放射性氙探测系统中的实用性,以实现更高的能量分辨率,同时最大限度地减少记忆效应。我们的研究结果表明,在 131mXe 的 129 keV 转换电子峰,能量分辨率大幅提高了 7.8%(与塑料探测器相比提高了约 3 倍)。改进后的系统为开发具有优化几何形状的运行系统奠定了基础,可用于辨别放射性氙同位素。
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引用次数: 0
Multi-parameter Imaging by Finite Difference Frequency Domain Full Waveform Inversion of GPR Data: A Guide for Sedimentary Architecture Modeling 通过有限差分频域全波形反演 GPR 数据进行多参数成像:沉积构造建模指南
IF 1.9 4区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2024-06-14 DOI: 10.1007/s00024-024-03520-1
Mrinal Kanti Layek, Probal Sengupta

The need for reconstruction of the distribution of physical properties like dielectric permittivity and electrical conductivity of shallow subsurface sedimentary architecture leads to the development of an optimum strategy of GPR data inversion. In this paper, we present finite difference frequency domain (FDFD) full waveform inversion (FWI) method to get high-resolution subsurface model using GPR data. FWI is an optimization technique which involves in search of the minima between recorded and predicted data. The inversion process includes the quasi-Newton method and simultaneous frequency sampling strategy of irregular sampling. The Hessian term in quasi-Newton algorithm is approximated using preconditioned-LBFGS consideration and the search directions are also optimized after following the Wolfe conditions. At the end of each iteration during inversion, permittivity and conductivity models were updated and became ready to be the initial model for the next iteration. The goals of this research were to develop a robust framework for sedimentary-GPR data inversion and to evaluate the efficacy of the novel grid strategy introduced by Layek and Sengupta (2021) proposed for FWI. This paper presents a comparative analysis between conventional and newly proposed technique from Layek and Sengupta (2021), supported by numerical experiments conducted through our own MATLAB programming. Numerical tests conducted on a benchmark from previously published article, established the fact that new grid formulation produces a faster converging rate and required less computation time. This approach demonstrates remarkable efficacy when applied to a comprehensive sedimentary model comprising a lossy medium.

由于需要重建浅表次表层沉积结构的介电常数和导电率等物理性质的分布,因此需要开发一种最佳的 GPR 数据反演策略。本文提出了有限差分频域(FDFD)全波形反演(FWI)方法,利用 GPR 数据获得高分辨率地下模型。全波形反演是一种优化技术,涉及寻找记录数据和预测数据之间的最小值。反演过程包括准牛顿法和不规则采样的同步频率采样策略。准牛顿算法中的 Hessian 项使用预处理-LBFGS 考虑近似,搜索方向也在遵循 Wolfe 条件后进行优化。在反演过程中的每次迭代结束时,都会更新介电常数和电导率模型,并将其作为下一次迭代的初始模型。本研究的目标是为沉积物-GPR 数据反演开发一个稳健的框架,并评估 Layek 和 Sengupta(2021 年)为 FWI 提出的新型网格策略的有效性。本文对 Layek 和 Sengupta(2021 年)提出的传统技术和新技术进行了比较分析,并通过我们自己的 MATLAB 编程进行了数值实验。对以前发表的文章中的基准进行的数值测试表明,新的网格计算方法收敛速度更快,所需的计算时间更少。这种方法在应用于包含有损介质的综合沉积模型时,显示出卓越的功效。
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引用次数: 0
A Review of Tsunamis Generated by Volcanoes (TGV) Source Mechanism, Modelling, Monitoring and Warning Systems 火山引发的海啸(TGV)来源机制、建模、监测和预警系统综述
IF 1.9 4区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2024-06-14 DOI: 10.1007/s00024-024-03515-y
François Schindelé, Laura Kong, Emily M. Lane, Raphaël Paris, Maurizio Ripepe, Vasily Titov, Rick Bailey

Tsunamis generated by volcanic eruptions have risen to prominence since the December 2018 tsunami generated by the flank collapse of Anak Krakatau during a moderate eruption and then the global tsunami generated by the explosive eruption of the Hunga volcano in the Tongan Archipelago in January 2022. Both events cause fatalities and highlight the lack in tsunami warning systems to detect and warn for tsunamis induced by volcanic mechanisms. Following the Hunga Tonga—Hunga Ha’apai eruption and tsunami, an ad hoc working group on Tsunamis Generated by Volcanoes was formed by the Intergovernmental Oceanographic Commission of UNESCO. Volcanic tsunamis differ from seismic tsunamis in that there are a wide range of source mechanisms that can generate the tsunamis waves and this makes understanding, modelling and monitoring volcanic tsunamis much more difficult than seismic tsunamis. This paper provides a review of both the mechanisms behind volcanic tsunamis and the variety of modelling techniques that can be used to simulate their effects for tsunami hazard assessment and forecasting. It gives an example of a volcanic tsunami risk assessment undertaken for Stromboli, outlines the requirement of volcanic monitoring to warn for tsunami hazard and provides examples of volcanic tsunami warning systems in Italy, the Hawaiian Island (USA), Tonga and Indonesia. The paper finishes by highlighting the need for implementing monitoring and warning systems for volcanic tsunamis for locations with submarine volcanoes or near-shore volcanoes which could potentially generate tsunamis.

自 2018 年 12 月喀拉喀托火山(Anak Krakatau)中度喷发时侧面坍塌引发海啸,以及 2022 年 1 月汤加群岛洪加火山(Hunga volcano)爆炸性喷发引发全球海啸以来,火山爆发引发的海啸日益突出。这两起事件都造成了人员伤亡,凸显了海啸预警系统在探测和预警火山机制引发的海啸方面的不足。在 Hunga Tonga-Hunga Ha'apai 火山喷发和海啸之后,教科文组织政府间海洋学委员会成立了一个火山引发海啸问题特设工作组。火山海啸与地震海啸的不同之处在于,可以产生海啸波的来源机制多种多样,这使得了解、模拟和监测火山海啸要比地震海啸困难得多。本文综述了火山海啸背后的机制,以及可用于海啸危害评估和预报模拟其影响的各种建模技术。论文举例说明了对斯特龙博利岛进行的火山海啸风险评估,概述了火山监测对海啸危害预警的要求,并举例说明了意大利、夏威夷岛(美国)、汤加和印度尼西亚的火山海啸预警系统。文件最后强调,有可能引发海啸的海底火山或近岸火山所在地需要实施火山海啸监测和预警系统。
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引用次数: 0
Evaluation of the Thermal Regime of the Southern Bida and Northern Anambra Basins, Nigeria: Insights from Aeromagnetic and Remote Sensing Data 尼日利亚南部比达盆地和北部阿南布拉盆地热制度评估:从航磁和遥感数据中获得的启示
IF 1.9 4区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2024-06-13 DOI: 10.1007/s00024-024-03516-x
Naheem Banji Salawu, Olusola Johnson Ojo

The Bida and Anambra Basins are major inland sedimentary basins located in the central and southern part of Nigeria with possible hydrocarbon potential but lack exploratory data. The present study aims at providing base line information on the thermal regime of the sedimentary basins, which would significantly contribute to its hydrocarbon prospect, investment opportunity and exploitation. The spectral analysis of the aeromagnetic anomaly data from the southern Bida Basin, northern Anambra Basin and adjacent basement complex terrain reveals the Curie point depth (CPD), geothermal gradient and heat flow in the region. The data reveals a CPD that varies between 19 and 30 km while the geothermal gradient is from 23 to more than 44 °C/km with heat flow values ranging from 50 to 109 mW/m2 in the southern Bida Basin. In the northern Anambra Basin, the CPD values range from 6.8 to 20 km and the heat flow values vary between 59 mWm2 and 109 mWm2, with a localized shallow CPD value of less than 6.8 km and associated high heat flow of 109 mWm2 in the central part of the basin. The delineated thermal patterns in the Bida and Anambra Basins are interpreted to be associated with the intrusions and the presence of deep-seated rift. The interpretation of the aeromagnetic data shows good agreement with the land surface temperature obtained from remote sensing data of the study area. The distribution of heat patterns in the southern Bida and northern Anambra Basins have implications for geothermal, source rock maturation and hydrocarbon generation evaluation of the basins.

比达盆地和阿南布拉盆地是位于尼日利亚中部和南部的主要内陆沉积盆地,可能具有油气潜力,但缺乏勘探数据。本研究旨在提供有关沉积盆地热机制的基础信息,这将极大地促进其油气勘探、投资机会和开采。对南部比达盆地、北部阿南布拉盆地和邻近基底复合地形的航空磁异常数据进行频谱分析,揭示了该地区的居里点深度(CPD)、地热梯度和热流。数据显示,在比达盆地南部,居里点深度在 19 至 30 千米之间,地热梯度在 23 至 44 °C/千米以上,热流值在 50 至 109 mW/m2 之间。在阿南布拉盆地北部,CPD 值在 6.8 至 20 千米之间,热流值在 59 mWm2 至 109 mWm2 之间,盆地中部的局部浅层 CPD 值小于 6.8 千米,相关热流值高达 109 mWm2。据解释,比达盆地和阿南布拉盆地的热模式与侵入体和深层裂谷的存在有关。对航磁数据的解释与研究地区遥感数据获得的地表温度十分吻合。比达盆地南部和阿南布拉盆地北部的热模式分布对盆地的地热、源岩成熟和碳氢化合物生成评估具有影响。
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引用次数: 0
Impact of the Solar Activity Variations on the Low-Latitude Day-to-Day Variability of NmF2 During Geomagnetically Quiet Conditions Obtained from the Huancayo and Jicamarca Ionosonde Observations 从万卡约和 Jicamarca 电离层观测获得的地磁静止条件下太阳活动变化对低纬度 NmF2 日间变化的影响
IF 1.9 4区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2024-06-10 DOI: 10.1007/s00024-024-03503-2
A. V. Pavlov, N. M. Pavlova

The statistical characteristics of the day-to-day variability of the F2-layer peak electron number density, NmF2, measured by the low-latitude Huancayo and Jicamarca ionosondes are studied for each month, M, in a year for geomagnetically quiet conditions at low and moderate solar activity during the time period from 1957 to 2022. The NmF2 statistical parameters under study are the mathematical expectation NmF2E, the arithmetically average NmF2A, the standard deviations σE(UT,M), and the variation coefficient CVE(UT,M) of NmF2 relative to NmF2E, where UT is the universal time. It is found that the value of CVE(UT,M) that determines the relative day-to-day variability of NmF2 is changed in the intervals of 15–68% and 14–68% for the low and moderate solar activity conditions, respectively. The comparison of CVE(UT,M) for the low and moderate solar activity conditions under consideration shows for the first time that the increase in the solar activity level increases or decreases the relative day-to-day NmF2 variability in the range from − 24 to 15%. In the vast majority of cases the considered increase in the solar activity level decreases the relative day-to-day NmF2 variability while the longest periods of the corresponding increase in the relative day-to-day NmF2 variability occur in April.

研究了 1957 年至 2022 年期间低纬度万卡约和 Jicamarca 电离探空仪测量的 F2 层峰值电子数密度 NmF2 的逐日变化统计特征。研究的 NmF2 统计参数包括数学期望 NmF2E、算术平均 NmF2A、标准偏差 σE(UT,M)和 NmF2 相对于 NmF2E 的变化系数 CVE(UT,M),其中 UT 为全球时间。结果发现,在低太阳活动和中太阳活动条件下,决定 NmF2 相对日变率的 CVE(UT,M) 值变化区间分别为 15-68% 和 14-68%。对低度和中度太阳活动条件下的 CVE(UT,M)进行比较后首次发现,太阳活动水平的增加会使 NmF2 的相对日变化率在-24%到 15%的范围内增大或减小。在绝大多数情况下,太阳活动水平的增加会降低 NmF2 的相对逐日变化率,而 NmF2 的相对逐日变化率相应增加的最长时期出现在 4 月份。
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引用次数: 0
Spatial Variation of Aquifer Permeability in the North China Plain from Large Magnitude Earthquake Signals 从大震信号看华北平原含水层渗透性的空间变化
IF 1.9 4区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2024-06-06 DOI: 10.1007/s00024-024-03511-2
Hongbiao Gu, Yirong Xu, Shuangshuang Lan, Mingxin Yue, Mingyuan Wang, Martin Sauter

Permeability changes induced by earthquakes have been studied widely. However, basic questions still remain: what are the spatial differences in permeability changes induced by far-field earthquakes? Is there an inevitable relationship between seismic energy density, epicenter azimuth and permeability change? We try to answer the above questions by examining records of 11 years of groundwater hydrographs of 7 wells in the North China plain at large distance from the epicenters of 221 earthquakes during the period 2008 ~ 2018. The results shows permeability changes varied between the different wells, with the permeability variation of the JN well most sensitively responding to seismic events, while the least sensitive wells being SH, JZ and LK. We found that the azimuths of seismic waves can greatly influence the changes in permeability, i.e. mainly concentrated between 25 and 295°. The seismic density energy (SDE) value larger than approximately 10–9 J/m3 is likely to induce a change in permeability in the NCP aquifer materials. It is found that SDE is not a predictor of permeability change at a given well, by calculating the seismic energy density which did not cause permeability change. While the permeability change ratio before and after the earthquake can be considered as the ability of permeability respond to the dynamic stress and it shows a weak correlation with depth of aquifer. Thus, Factors that probably affect permeability responses changes would have implications for crustal geomechanics.

地震引起的渗透性变化已被广泛研究。然而,基本问题仍然存在:远场地震诱发的渗透率变化在空间上有何差异?地震能量密度、震中方位角与渗透率变化之间是否存在必然联系?我们通过研究 2008~2018 年间华北平原距 221 次地震震中较大距离的 7 口井 11 年的地下水水文图记录,试图回答上述问题。结果表明,不同井的渗透率变化各不相同,其中 JN 井的渗透率变化对地震事件的响应最为敏感,而 SH、JZ 和 LK 井的渗透率变化对地震事件的响应最不敏感。我们发现地震波的方位角对渗透率的变化有很大影响,即主要集中在 25 至 295°之间。地震密度能(SDE)值大于约 10-9 J/m3 时,可能会引起 NCP 含水层材料渗透率的变化。通过计算未引起渗透率变化的地震能量密度,发现 SDE 并不能预测特定井的渗透率变化。而地震前后的渗透率变化比可视为渗透率对动态应力的响应能力,它与含水层深度的相关性较弱。因此,可能影响渗透性响应变化的因素将对地壳地质力学产生影响。
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引用次数: 0
Nonlinear Burgers Type Equation for Acoustic Waves in the Ray Approximation in a Moving Atmosphere (Theory, Experiment) 移动大气中射线近似声波的非线性布尔格斯型方程(理论、实验)
IF 1.9 4区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2024-06-06 DOI: 10.1007/s00024-024-03505-0
Sergey Kshevetskii, Sergey Kulichkov, Igor Chunchuzov, Marat Zakirov, Elena Golikova, Evgenia Anufrieva, Irina Vereschagina

The derivation of a nonlinear Burgers-type equation for acoustic waves within the ray approximation for an inhomogeneous moving dissipative atmosphere is presented. The equation is applied to investigate the propagation of three-dimensional infrasonic waves, without using significant computational resources. By means of solving the obtained equation, the shapes of infrasonic signals recorded at distances of 295 km and 305 km from the explosion with energy of 30 kt THT were calculated. The observation point at the distance of 295 km (Tsimlyansk) was located in the western direction from the source. At this place, infrasonic signals were recorded corresponding to the sound propagation in the stratospheric and thermospheric acoustic waveguides. The presence of both two stratospheric and two thermospheric rays falling into the same observation point on the Earth's surface is a wave propagation feature result here. The recorded signals in Tsimlyansk also have a complex structure, both for stratospheric and thermospheric infrasonic arrivals. The registration point at a distance of 305 km (Saratov) was located north of the source. For this point, the calculations showed the presence of only thermospheric rays. The calculation results are compared with experimental data. A satisfactory agreement between the calculated and experimental data was obtained for both observation points in Saratov and Tsimlyansk. The calculated data in Tsimlyansk include manifestation features of the multipath structure of infrasound propagation and agree with the complex structure of infrasound signals recorded in Tsimlyansk.

在非均质运动耗散大气的射线近似中,介绍了声波的非线性伯格斯型方程的推导。该方程用于研究三维次声波的传播,无需使用大量计算资源。通过求解所得到的方程,计算了在距离爆炸点 295 千米和 305 千米处记录到的次声波信号的形状,其能量为 30 kt THT。距离 295 千米(齐姆良斯克)的观测点位于爆炸源的西面。在该观测点记录了与声音在平流层和热层声波导管中传播相对应的次声波信号。两个平流层和两个热层射线同时落在地球表面的同一个观测点上,这是这里产生的波传播特征。在齐姆良斯克记录到的信号结构也很复杂,既有平流层次声波到达,也有热层次声波到达。距离 305 公里(萨拉托夫)的登记点位于信号源以北。计算显示,该点只存在热层射线。计算结果与实验数据进行了比较。在萨拉托夫和齐姆扬斯克的两个观测点上,计算数据和实验数据的一致性令人满意。齐姆良斯克的计算数据包括次声波传播多径结构的表现特征,并与齐姆良斯克记录的次声波信号的复杂结构相吻合。
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引用次数: 0
Correction: Systematic Seismic Events Discrimination Methods at the Kenya National Data Centre (N090) 更正:肯尼亚国家数据中心的系统地震事件判别方法(N090)
IF 1.9 4区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2024-06-03 DOI: 10.1007/s00024-024-03495-z
Josphat K. Mulwa
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引用次数: 0
Extent of Thin Surfacial Fracture Detection Using Geophysical Survey: A Case Study of Parwan Gravity Dam, Jhalawar, Rajasthan, India 利用地球物理勘测探测薄地表断裂的范围:印度拉贾斯坦邦贾拉瓦尔帕尔万重力坝案例研究
IF 1.9 4区 地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2024-06-01 DOI: 10.1007/s00024-024-03513-0
Jyoti Singh, Anand Joshi, Saurabh Sharma, Mohit Pandey, Anamika Sahu, Sandeep Singh, Krishna Mohan Jaiswal

Parwan Gravity Dam is under construction stage in the Jhalawar district of Rajasthan, India. A thin sub-vertical surficial fracture trending N 75°W to S 75°E has been observed in the foundation area of the dam. Geophysical techniques such as electrical resistivity tomography (ERT), seismic refraction tomography (SRT), and multichannel analysis of surface waves (MASW) are utilized extensively in the field of civil engineering, exploration geophysics for the assessment and construction of large-scale infrastructures such as dams. These methods provide critical information about the subsurface conditions without the need of extensive drilling and excavation. The combination of electrical resistivity tomography (ERT), seismic refraction (SR), and multichannel analysis of surface waves (MASW) techniques with the different acquisition parameters have been used to image the extent of shallow subsurface geological structures. Various geophysical Surveys have been carried out along several profiles in the longitudinal direction and along the transverse direction to the fault axis. A total of 13 refraction and resistivity profiles were conducted of which 9 were transverse profiles and 4 were longitudinal profiles. A total of nine MASW profiles were conducted of which 8 are transverse profiles and 1 is a longitudinal profile. In this paper, the subsurface distribution of seismic wave velocity and electrical resistivity have been studied to identify any possible anomalous zone in bedrock and to detect the downward extension of surface fracture of brittle fault using the afore mentioned methods. The vertical and lateral extent of the surface fracture of the fault has been investigated by the analysis of these survey results. The analysis of the results indicates that a very tight and narrow fracture is present in the shallow subsurface.

帕尔万重力坝位于印度拉贾斯坦邦贾拉瓦尔地区,目前正处于施工阶段。在大坝的地基区域观察到了一条细长的次垂直地表断裂,其走向为 N 75°W 至 S 75°E。电阻率层析成像(ERT)、地震折射层析成像(SRT)和表面波多通道分析(MASW)等地球物理技术被广泛应用于土木工程和勘探地球物理领域,以评估和建造大坝等大型基础设施。这些方法可提供有关地下条件的重要信息,而无需进行大量钻探和挖掘。电阻率层析成像(ERT)、地震折射(SR)和多道面波分析(MASW)技术与不同的采集参数相结合,已被用于对浅层地下地质结构的范围进行成像。沿断层轴线的纵向和横向的几个剖面进行了各种地球物理勘测。共进行了 13 次折射和电阻率剖面测量,其中 9 次为横向剖面测量,4 次为纵向剖面测量。共绘制了 9 个 MASW 剖面图,其中 8 个为横向剖面图,1 个为纵向剖面图。本文对地震波速度和电阻率的地下分布进行了研究,以确定基岩中可能存在的异常区,并利用上述方法探测脆性断层表面断裂向下延伸的情况。通过分析这些勘测结果,对断层表面断裂的垂直和横向范围进行了调查。结果分析表明,在浅层地下存在一条非常紧密和狭窄的断裂。
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pure and applied geophysics
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