International Journal of Geophysics最新文献_第3页

Ambient Noise

� H � / � V �

Spectral Ratio in Site Effect Estimation in La Mesa de Macaracas, Panama 巴拿马La Mesa de Macaracas场地效应估算中的环境噪声H/V谱比

IF 1.1

International Journal of Geophysics Pub Date : 2022-03-29 DOI: 10.1155/2022/6171529

J. L. De Guevara, A. Mojica, A. Ruiz, C. Ho, Kenia Rodríguez, J. Toral, J. Fábrega

{"title":"Ambient Noise <math xmlns=\"http://www.w3.org/1998/Math/MathML\" id=\"M1\">\u0000 <mi>H</mi>\u0000 <mo>/</mo>\u0000 <mi>V</mi>\u0000 </math> Spectral Ratio in Site Effect Estimation in La Mesa de Macaracas, Panama","authors":"J. L. De Guevara, A. Mojica, A. Ruiz, C. Ho, Kenia Rodríguez, J. Toral, J. Fábrega","doi":"10.1155/2022/6171529","DOIUrl":"https://doi.org/10.1155/2022/6171529","url":null,"abstract":"In the last 10 years, the community of La Mesa de Macaracas (central Panama) has experienced considerable aftershocks due to earthquakes of magnitudes up to 5.7 Mw. Although most of the community consists of single-storey houses, the agricultural development in the region has led to multistorey building projects. To determine whether the characteristics of the soils could affect future construction in the study area, 16 stations were established to measure ambient vibrations and estimate the predominant frequencies and their corresponding \u0000 \u0000 H\u0000 /\u0000 V\u0000 \u0000 ratio peaks through the ambient noise \u0000 \u0000 H\u0000 /\u0000 V\u0000 \u0000 spectral ratio technique. According to the site class established by the Japan Road Association, the results revealed the existence of (a) soft soil with a range of predominant frequencies between 0.7 and 1.6 Hz, (b) medium soil with a range of predominant frequencies between 2.1 and 2.4 Hz, and (c) hard soil with a range of predominant frequencies between 2.6 and 2.9 Hz. In the first type (soft), the resonance effect could affect constructions of between 6 and 14 storeys with \u0000 \u0000 H\u0000 /\u0000 V\u0000 \u0000 ratio peak values (amplification factor) in the range of 2.1 and 4.3, while in the second and third types (medium and hard soils), buildings of between 3 and 5 storeys could be affected, with \u0000 \u0000 H\u0000 /\u0000 V\u0000 \u0000 ratio peak values (1.5–2.0) except at the SS-9 station. These results were complemented with the \u0000 \u0000 \u0000 \u0000 V\u0000 \u0000 \u0000 s\u0000 \u0000 \u0000 \u0000 \u0000 30\u0000 \u0000 \u0000 \u0000 values obtained in four seismic soundings carried out at the site.","PeriodicalId":45602,"journal":{"name":"International Journal of Geophysics","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46665210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Identification of Geothermal Reservoirs in South Cameroon from a Combined Landsat 8 and AMT Data 利用Landsat 8和AMT联合数据识别喀麦隆南部地热储层

IF 1.1

International Journal of Geophysics Pub Date : 2022-02-14 DOI: 10.1155/2022/1324766

Piameu Kwagag Joel, Owona Angue Marie Louise-Clotilde, N. Evariste, Njingti Nfor, Kue Petou Rokis Malquaire, N. Philippe

{"title":"Identification of Geothermal Reservoirs in South Cameroon from a Combined Landsat 8 and AMT Data","authors":"Piameu Kwagag Joel, Owona Angue Marie Louise-Clotilde, N. Evariste, Njingti Nfor, Kue Petou Rokis Malquaire, N. Philippe","doi":"10.1155/2022/1324766","DOIUrl":"https://doi.org/10.1155/2022/1324766","url":null,"abstract":"This geothermal source prospecting work is carried out in order to respond to the energy deficit affecting the populations of South Cameroon in particular. The study combines audio-magnetotelluric (AMT) and Landsat 8 data for the geolocation of reservoirs, as well as the geological and tectonic information. The processing of these data defined 5 profiles and led to two-dimensional models of resistivity sections for each profile. The interpretation of the data identified a highly conductive zone with a resistivity ranged 1–10 Ω·m at an estimated depth of 1200 m in the locality of Menve’ele. The Landsat 8 data collected in this area during the same period enabled the elaboration of temperature and lineament anomaly maps of the study area. High-temperature areas with high lineament predominance correlate better with areas of low resistivity. For example, Menve’ele (A1) has a surface temperature range of 20°C–30°C and a high density of lineaments. By correlating these results with those provided by previous authors, the Menve’ele locality may be the target of a potential geothermal reservoir. A 3D resistivity model is built to better understand the variations of resistivity and their depths. The geological and tectonic information of the region confirm the tectonic origin of the faults and lineaments as well as the predominance of metamorphic and sedimentary formations.","PeriodicalId":45602,"journal":{"name":"International Journal of Geophysics","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43974907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Delineation of Subsurface Structures Using Gravity Data of the Shallow Offshore, Lamu Basin, Kenya 利用肯尼亚Lamu盆地浅海重力资料圈定地下构造

IF 1.1

International Journal of Geophysics Pub Date : 2022-01-27 DOI: 10.1155/2022/3024977

D. Ombati, J. Githiri, M. K’Orowe, E. Nyakundi

{"title":"Delineation of Subsurface Structures Using Gravity Data of the Shallow Offshore, Lamu Basin, Kenya","authors":"D. Ombati, J. Githiri, M. K’Orowe, E. Nyakundi","doi":"10.1155/2022/3024977","DOIUrl":"https://doi.org/10.1155/2022/3024977","url":null,"abstract":"Lamu Basin is located in South Eastern Kenya and covers about 170 000 km2 both onshore and offshore. Kenya’s Lamu Basin is hitherto underexplored even though there have been notable oil and gas discoveries along the margin of East Africa. This study focuses on the shallow section of the Lamu offshore bounded by 39°E to 43°E by 2°S to 6°S, whereby, unfortunately, some of the wildcat wells turned out to be dry although expensive. Gravity interpretation techniques such as spectral analysis and first horizontal derivative were applied to the reduced gravity data to delineate and model structures to minimize the high investment risks. The gravity data used in this study were sourced from the International Gravity Bureau (BGI) and National Oil Corporation of Kenya (NOCK) digital data courtesy of companies like Woodside Energy, Anadarko Kenya Limited, and Total Exploration and Production companies. The obtained reduced gravity data were gridded to produce the gravity anomaly grids (Free air, Bouguer, and Isostacy), which were consequently drawn into maps. From spectral analysis, depths to shallow sources and deep sources were estimated. These depths were used to set regional and residual separation filters using the Gaussian filter. The first horizontal derivative (FHD) applied to the regional Isostatic gravity anomaly map yielded features that were inferred as intrasediment fractures/faults trending in NW-SE and NE-SW directions. The features like the ridges, troughs, and faults mainly trending in the NW-SE direction are discernable from the regional anomaly map. The developed models show the basement highs and lows with a possibility of anticlinal and synclinal structures and thick sedimentary successions likely to represent good hydrocarbon source kitchens.","PeriodicalId":45602,"journal":{"name":"International Journal of Geophysics","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2022-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45102884","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Intrusive Seismic Swarms as Possible Precursors of Destructive Earthquakes on Mt. Etna’s Eastern Flank 侵入性地震群是埃特纳火山东翼破坏性地震的可能先兆

IF 1.1

International Journal of Geophysics Pub Date : 2021-03-22 DOI: 10.21203/RS.3.RS-288277/V1

S. Gambino, G. Distefano

{"title":"Intrusive Seismic Swarms as Possible Precursors of Destructive Earthquakes on Mt. Etna’s Eastern Flank","authors":"S. Gambino, G. Distefano","doi":"10.21203/RS.3.RS-288277/V1","DOIUrl":"https://doi.org/10.21203/RS.3.RS-288277/V1","url":null,"abstract":"\u0000 The Timpe Fault System (TFS) represents the source of shallow earthquakes that strike numerous towns and villages on Mt. Etna eastern flank. In the last 40 years, three destructive seismic events reached I0 = VIII EMS (heavily damaging) - in 1984 (October 25), 2002 (October 29) and 2018 (December 26). These events followed a few days after the occurrence of strong seismic swarms and the sudden acceleration of the eastern flank seaward. However, if the 2002 and 2018 events were caused by stress induced by eruptive dike propagation, in October 1984 no eruption occurred. In this work, parameters such as localization, cumulative seismic moment and hourly occurrence frequency of the 1984 seismic swarm, have been analyzed and shown to have typical values of Mt. Etna intrusive seismic swarms. This suggests that the 1984 episode may have been an aborted intrusive magma episode that triggered similar processes (long and powerful intrusions with acceleration of the eastern flank movement and destructive earthquakes), as in 2002 and 2018. These three episodes suggest that an evaluation of some seismic parameters during future intrusive swarms may furnish indications of a possible re-activation of the TFS.","PeriodicalId":45602,"journal":{"name":"International Journal of Geophysics","volume":"1 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2021-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43023838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

First-Arrival Picking for Microseismic Monitoring Based on Deep Learning 基于深度学习的微震监测初到选择

IF 1.1

International Journal of Geophysics Pub Date : 2021-03-15 DOI: 10.1155/2021/5548346

Xiaolong Guo

{"title":"First-Arrival Picking for Microseismic Monitoring Based on Deep Learning","authors":"Xiaolong Guo","doi":"10.1155/2021/5548346","DOIUrl":"https://doi.org/10.1155/2021/5548346","url":null,"abstract":"In microseismic monitoring, achieving an accurate and efficient first-arrival picking is crucial for improving the accuracy and efficiency of microseismic time-difference source location. In the era of big data, the traditional first-arrival picking method cannot meet the real-time processing requirements of microseismic monitoring process. Using the advanced idea of deep learning-based end-to-end classification and the prominent feature extraction advantages of a fully convolution neural network, this paper proposes a first-arrival picking method of effective signals for microseismic monitoring based on UNet++ network, which can significantly improve the accuracy and efficiency of first-arrival picking. In this paper, we first introduced the methodology of the UNet++-based picking method. And then, the performance of the proposed method is verified by the experiments with finite-difference forward modeling simulated signals and actual microseismic records under different signal-to-noise ratios, and finally, comparative experiments are performed using the U-Net-based first-arrival picking algorithm and the Short-Term Average to Long-Term Average (STA/LTA) algorithm. The results show that compared to the U-Net network, the proposed method can obviously improve the first-arrival picking accuracy of the low signal-to-noise ratio microseismic signals, achieving significantly higher accuracy and efficiency than the STA/LTA algorithm, which is famous for its high efficiency in traditional algorithms.","PeriodicalId":45602,"journal":{"name":"International Journal of Geophysics","volume":"2021 1","pages":"1-14"},"PeriodicalIF":1.1,"publicationDate":"2021-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48155935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 4

Aquifer Vulnerability: Its Protection and Management—A Case Study in Pangkalpinang City, Indonesia 含水层脆弱性的保护与管理——以印度尼西亚潘卡尔皮南市为例

IF 1.1

International Journal of Geophysics Pub Date : 2020-12-29 DOI: 10.1155/2020/8887914

G. U. Nugraha, K. L. Gaol, P. Hartanto, H. Bakti

引用次数: 7

Seismic Velocity Structure in the Area of the 2007, Mw 8.0, Pisco-Peru Earthquake: Implications for the Mechanics of Subduction in the Vicinity of the Nazca Ridge 2007年秘鲁皮斯科8.0级地震区的地震速度结构：对纳斯卡山脊附近俯冲机制的启示

IF 1.1

International Journal of Geophysics Pub Date : 2020-11-05 DOI: 10.1155/2020/3874524

I. Bernal, H. Tavera

引用次数: 0

foF2 Seasonal Asymmetry Diurnal Variation Study during Very Quiet Geomagnetic Activity at Dakar Station 达喀尔站极静地磁活动期间foF2季节不对称日变化研究

IF 1.1

International Journal of Geophysics Pub Date : 2020-10-27 DOI: 10.1155/2020/8896188

Sibri Alphonse Sandwidi, D. A. Gnabahou, F. Ouattara

{"title":"foF2 Seasonal Asymmetry Diurnal Variation Study during Very Quiet Geomagnetic Activity at Dakar Station","authors":"Sibri Alphonse Sandwidi, D. A. Gnabahou, F. Ouattara","doi":"10.1155/2020/8896188","DOIUrl":"https://doi.org/10.1155/2020/8896188","url":null,"abstract":"This paper aims to study the foF2 seasonal asymmetry diurnal variation at Dakar station from 1976 to 1995. We show that equinoctial asymmetry is less pronounced and somewhere is absent throughout 21 and 22 solar cycles. The absence of equinoctial asymmetry may be due to Russell-McPherron mechanism and the vertical drift . The solstice anomaly or annual anomaly is always observed throughout both 21 and 22 solar cycles as measured at Dakar ionosonde. The maximum negative value of σfoF2, fairly equal to -65%, is observed during the decreasing phase at solstice time; this value appeared usually at 0200 LT except during the maximum phase during which it is observed at 2300 LT. The maximum positive value, fairly equal to +94%, is observed at 0600 LT during solar minimum at solstice time. This annual asymmetry may be due to neutral composition asymmetric variation and solar radiation annual asymmetry with the solstice time. The semiannual asymmetry is also observed during all solar cycle phases. The maximum positive value (+73%) is observed at 2300 LT during solar maximum, and its maximum negative (-12%) is observed during the increasing phase. We established, as the case of annual asymmetry, that this asymmetry could not be explained by the asymmetry in vertical velocity phenomenon but by the axial mechanism, the “thermospheric spoon” mechanism, and the seasonally varying eddy mixing phenomenon.","PeriodicalId":45602,"journal":{"name":"International Journal of Geophysics","volume":" ","pages":"1-10"},"PeriodicalIF":1.1,"publicationDate":"2020-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2020/8896188","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46763373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Ambient Seismic Noise Analysis Associated with the 2010 Eruption of Merapi Volcano Using Temporal Variations of Randomness and Background Noise 利用随机性和背景噪声的时间变化分析与2010年默拉皮火山爆发有关的环境地震噪声

IF 1.1

International Journal of Geophysics Pub Date : 2020-06-30 DOI: 10.1155/2020/8853376

Afif Rakhman, Wahyudi, A. Budi Santoso, H. Humaida, W. Suryanto

{"title":"Ambient Seismic Noise Analysis Associated with the 2010 Eruption of Merapi Volcano Using Temporal Variations of Randomness and Background Noise","authors":"Afif Rakhman, Wahyudi, A. Budi Santoso, H. Humaida, W. Suryanto","doi":"10.1155/2020/8853376","DOIUrl":"https://doi.org/10.1155/2020/8853376","url":null,"abstract":"We present the combination of permutation entropy (PE) and power spectral density (PSD) analysis on continuous seismic data recorded by short-period seismic stations during the 2010 Merapi volcano eruption. The calculation of PE aims at characterizing the randomness level in seismic noise, while the PSD parameters use to detect the background noise level in various frequency bands. It was previously observed that a significant reduction of randomness before the volcano eruption could be indicated as one of the short-term precursors due to the lack of high frequencies (>1 Hz) in the noise wave-field caused by high absorption losses as the hot magma uprises to the upper crust. The results show no significant reduction in signal randomness before the eruption series. The characteristic of events during the preeruptive period and the crisis tends to be chaotic (PE in the range 0.9 to 1). Further calculations show that the standard deviation in PE decreased in four days before the first eruption onset on 26 October. PE was stable at the highest values (very close to 1) and gradually returned to the previous fluctuation after the eruption onset. The level of background noise in the low- and high-frequency bands appeared to have the same tendency. The two main eruptions correspond to the two highest peaks of noise levels.","PeriodicalId":45602,"journal":{"name":"International Journal of Geophysics","volume":"2020 1","pages":"1-10"},"PeriodicalIF":1.1,"publicationDate":"2020-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1155/2020/8853376","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43905266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Typology of Sounding Curves and Lithological 1D Models of Mineral Prospecting and Groundwater Survey within Crystalline Basement Rocks in the East of Cameroon (Central Africa) Using Electrical Resistivity Method and Koefoed Computation Method 使用电阻率法和Koefoed计算法在喀麦隆东部（中非）结晶基岩内进行矿产勘探和地下水调查的测深曲线类型和岩性1D模型

IF 1.1

International Journal of Geophysics Pub Date : 2020-02-28 DOI: 10.1155/2020/8630406

Daniel Hervé Gouet, A. Meying, Harlin Leonid Ekoro Nkoungou, S. Assembe, P. Njandjock Nouck, Théophile Ndougsa Mbarga

引用次数: 17