VIETNAM JOURNAL OF EARTH SCIENCES最新文献

{"title":"Numerical modelling of slope stabilization with xathan gum-treated soil","authors":"An Tran Thi Phuong, Chang Ilhan, Nhan Tran Thanh, Cho Gye-Chun","doi":"10.15625/2615-9783/17924","DOIUrl":"https://doi.org/10.15625/2615-9783/17924","url":null,"abstract":"Biopolymer soil treatment has been introduced as the latest technological innovation in soil stabilization and improvement. Biopolymers with agar, guar, xanthan, casein, gellan and sodium alginate have been commonly studied to improve strength, reduce hydraulic conductivity and prevent erosion of highly permeable soil materials. Among those, xanthan gum is introduced to perform better in terms of lowering permeability. In this study, the effect of xanthan gum on slope stability under rainfall was evaluated via a 2D finite-difference program (FLAC) considering the wetting behavior of xanthan gum-treated soil. In order to obtain input parameters for numerical modelling, wetting soil-water characteristic tests, permeability tests, and direct shear tests were conducted on xanthan gum-treated soils. The numerical results support the application of biopolymers to soil erosion control during rainfall, mainly due to the significant decrease in the infiltration of xanthan gum-treated soil.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43624770","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}

{"title":"Magnetotellurics study of Atambua area, West Timor, Indonesia","authors":"Edy Wijanarko, I. Arisbaya, P. Sumintadireja, Warsa, H. Grandis","doi":"10.15625/2615-9783/17581","DOIUrl":"https://doi.org/10.15625/2615-9783/17581","url":null,"abstract":"Timor Island, located in the eastern Indonesian archipelago, has a complex tectonic evolution causing complex geological structures. Many hypothetical tectonic models are proposed mainly based on regional geological and geophysical data. Available geophysical data to support geological study at a more detailed scale are still very limited. Therefore, this study aimed to map the sub-regional subsurface geology in Atambua, West Timor, and its surroundings by using the magnetotelluric (MT) method. The estimated geo-electrical strike direction from the phase tensor analysis confirmed the regional Southwest - Northeast general structural orientation. The dimensionality analysis also showed the validity for 2D approximation in that direction. The subsurface resistivity models from 2D inversion of the MT data at representative lines perpendicular to the regional structural direction delineate the primary sequences and their boundaries from their resistivities. They are, from top to bottom, Viqueque and Bobonaro sequences, Kolbano sequence, Kekneno sequence, and the basement dominated by rocks with Australian affinity. These main rock formations represent the regional sedimentary depositional fill resulting from the major tectonic events on Timor Island.  ","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46708124","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}

{"title":"Effects of physical properties and undrained cyclic shear conditions on the pore water pressure responses of saturated sands and clays","authors":"Nhan Tran Thanh, H. Matsuda, An Tran Thi Phuong, Nhan Nguyen Thi Thanh, Tien Pham Van, Thien Do Quang","doi":"10.15625/2615-9783/17568","DOIUrl":"https://doi.org/10.15625/2615-9783/17568","url":null,"abstract":"For clarifying the effects of relative density (Dr) and Atterberg’s limits on the cyclic shear-induced pore water pressure properties of soils, sandy soils with similar index properties and clayey soils with different Atteberg’s limits were collected from Vietnam and Japan and used for this study. Specimens at Dr = 50% of Nam O sand and Dr = 70% of Toyoura sand, and those of Hue clay and Japanese Kaolin clay were consolidated under the vertical stress of σvo = 49 kPa. They were then subjected to undrained cyclic shear for various cyclic shear directions and wide ranges of the number of cycles and shear strain amplitudes. Under the same cyclic shearing conditions, specimens of sand at higher Dr (Toyoura sand) and clay with higher Atterberg’s limits (Kaolin) show a lower pore water pressure ratio. The number of cycles and the cumulative shear strain at the starting point of pore water pressure generation were observed for different soils and testing conditions. In addition, using the cumulative shear strain, a new strain path parameter, the effects of shear strain amplitude and cyclic shear direction can be captured, resulting in a unique uacc/σ’vo - G*  relation on each soil. Based on this, fitting lines can be drawn and referred to promote a prediction of the cyclic shear-induced pore water pressure accumulation for the used soils under different cyclic shear conditions.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42438133","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}

{"title":"Establishment of the correlation between the near-surface sedimentary thickness and the microtremor dominant frequency in the Hanoi area","authors":"Hung Nguyen-Tien, P. Nguyen-Hong, Minh-Tri Nguyen-Le, L. Che-Min, Nguyen Tran-An, Truyen Pham-The, Duong Nguyen-Van","doi":"10.15625/2615-9783/17569","DOIUrl":"https://doi.org/10.15625/2615-9783/17569","url":null,"abstract":" This paper established the correlation between the near-surface sedimentary thickness (D) and the microtremor dominant frequency (F0) in the Hanoi area based on 64 microtremor measuring points at the boreholes with depth to bedrock. The microtremor dominant frequency was determined using the horizontal-to-vertical (H/V) spectral ratio of the seismic noise technique proposed by Nakamura (1989). The near-surface sedimentary thickness was determined according to the borehole data from the previously published reports. The non-linear regression method was applied to the pairs of D and F0 values from 64 boreholes to obtain the relationship of form D = 81.851*F0-0.942. This correlation function was used to determine the values of the near-surface sedimentary thickness at microtremor measurement points according to the F0 values. Comparison of the D-values obtained in this study with those from the boreholes data shows good coincidence by values and variation tendency, especially in areas with shallow cover thickness from 50 to 100 m. The above results allow the proposal of a new near-surface sedimentary thickness determination technique in the Hanoi area.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46136434","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}

{"title":"Ionospheric quasi-biennial oscillation of the TEC amplitude of the equatorial ionization anomaly crests from continuous GPS data in the Southeast Asian region","authors":"Dung Nguyen Thanh, M. Huy, C. Amory-Mazaudier, R. Fleury, S. Saito, Thang Nguyen Chien, T. L. Truong, H. P. Thu, T. N. Ha, Mai Nguyen Thi, Que Le","doi":"10.15625/2615-9783/17490","DOIUrl":"https://doi.org/10.15625/2615-9783/17490","url":null,"abstract":"The quasi-biennial oscillation (QBO) signals at two Equatorial ionization anomaly (EIA) crests of the ionosphere have been studied using the continuous GNSS network data in Vietnam and adjacent regions during the 2008- 2021 period. The monthly mean EIA crests amplitudes are calculated. The Lomb-Scargle periodogram method was applied to the residuals of the EIA crests magnitudes, DTEC, which are obtained from subtracting the fittings with solar index, F10.7. The Lomb-Scargle spectrum shows the quasi-biennial component in the residuals DTEC with the picks at 18, 25, and 29-30 months. The ionosphere QBO at two EIA crests was found out by the band-pass filter centered at 25 months with haft-power points at 17 and 33 months. The zonal wind data at 50 hPa (~ 20 km) of the tropical equatorial stratosphere is used as the stratosphere QBO (SQBO) to consider the relationship between the SQBO and the obtained ionosphere QBO. The direct comparison and the cross wavelet transform of the SQBO and ionosphere QBO data series show that during 2008-2009, the ionosphere QBO signal is low, the SQBO and ionosphere QBO are in phase during the 2010-2013 and 2018-2021 periods, but anti-phase during the 2014-2017 period. For the 2010-2013, 2014-2017 and 2018-2021 periods, the correlation coefficients are 0.623, 0.637, -0.646 in the northern crest, and 0.571, 0.53, -0.530 in the southern crest, respectively. Furthermore, we also observed that the SQBO and the ionosphere QBO signals were shortened during the 2015-2016 period, approximately 1.5 years. Previous studies showed that the ENSO (El Niño - Southern Oscillation) warm phase, also known as El-Niño existed during 2015-2016. The results of this study allow us to assume that the SQBO influences the ionosphere QBO. Our results show that the SQBO is the main factor affecting the ionospheric QBO at two EIA crests. However, the physical theoretical interpretation of the mechanisms of action is a challenge for scientists and requires further research.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47366485","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}

{"title":"Microplastics in the Surface Sediment of the main Red River Estuary","authors":"N. Le, Thi Thu Hang Hoang, T. Duong, N. Phuong, P. Le, T. Nguyen, T. X. B. Phung, Thi My Hanh Le, Thi Lien Le, T. Vu, T. Le","doi":"10.15625/2615-9783/17486","DOIUrl":"https://doi.org/10.15625/2615-9783/17486","url":null,"abstract":"Microplastics (< 5mm) are one emerging pollutant in the environment. These are the threats and challenges facing the global environment, economy, and society, especially in hotspot regions such as Asia. This paper presents the microplastic characteristics found in the surface sediment of the main Red River estuary (the Ba Lat) during four separate monitoring runs in 2020. The microplastic amount in the sediment samples varied from 800 items per kg of dried weight (dw) to 3,817 items.kg-1 dw, averaging 2,188 ± 1,499 items.kg-1 dw. Fiber and fragment microplastics were discovered to be primary shapes, of which fibers dominated (94%). Microplastic fiber sizes were found mainly in the < 500 µm (69%) range. The most primarily observed colors of microplastics were blue (36%), white (21%), and red (11%). There were five recognized polymer types (polypropylene (PP), polyethylene (PE), polyurethane (PU), polyamide (PA), and polystyrene (PS)) in the sediment samples, with PE and PP predominating. Seasonal fluctuations in microplastic concentrations at the Ba Lat site, a significant aquaculture zone, may indicate the contribution of multiple sources. Our research demonstrated the necessity of microplastic observation in organisms, particularly in the aquaculture zones in Vietnam. Our findings further underline the importance of managing and minimizing the amount of plastic garbage that enters the ecosystem.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48545512","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}

{"title":"Assessment of machine learning techniques for prediction of integrated water vapor using meteorological data","authors":"Nirmala Bai Jadala, M. Sridhar, D. Venkata Ratnam, G. Dutta","doi":"10.15625/2615-9783/17373","DOIUrl":"https://doi.org/10.15625/2615-9783/17373","url":null,"abstract":"Weather and Climatological studies are very important in assessing atmospheric conditions like storms and cyclones. Integrated water vapor (IWV) is an important greenhouse gas in the atmosphere responsible for the Earth's radiative balance. Global Positioning System (GPS) observations have been used for monitoring the IWV variability.  The IWV estimations are carried out using ground-based GPS observations at Hyderabad (17.4°N, 78.46°E), India using GAMIT software. GAMIT is GPS analysis software developed by MIT, USA. It takes input as GPS observation data containing pseudo ranges, navigation data containing ephemeris, clock errors, g-files with orbital information, and meteorological data like pressure, temperature, and relative humidity to calculate IWV. However, estimating IWV for forecasting applications is impossible with a GPS system. This paper introduces a methodology to predict IWV during normal days and severe cyclonic events using machine learning (ML) techniques. Rational quadratic Gaussian process regression (RQ-GPR) and neural network (NN) algorithms are considered for identifying suitable ML prediction algorithms over tropical conditions. Meteorological surface data like Pressure, Temperature, and relative humidity are given as input to the machine learning models. The IWV values computed from GPS are compared with the model's predicted values. RQ-GPR model is showing good accuracy with the IWV values computed from GPS against the NN model. The correlation coefficient (ρ) achieved for RQ-GPR is 0.93, and 0.86 is obtained for the NN model. \u0000The RMSE (Root Mean Square Error) of the predicted IWV value with RQ-GPR is better than the NN model. We have obtained mean square error (MSE) and mean absolute error (MAE) as 18.146 kg/m2 and 3.0762 kg/m2 for RQ-GPR and 27.509 kg/m2 and 3.9102 kg/m2 for the NN model which is showing RQ-GPR is a suitable model for forecasting applications. The HUDHUD cyclonic event that occurred in October 2014 is considered for testing the proposed ML algorithms. RQ-GPR model has better results in the Prediction of IWV than the NN model. The RMSE value obtained is 2.837 kg/m2 for RQ-GPR and 3.327 kg/m2 obtained from the NN model. The results indicate that the RQ-GPR model has more accuracy than the other IWV prediction models. The prediction results are helpful for meteorology, weather, and climatology studies and useful to improve the accuracy of the regional numerical weather prediction models.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45169654","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}

{"title":"Comprehensive assessment of coastal tourism potential in Vietnam","authors":"Huong Hoang Thi Thu, Bac Kinh Dang, A. van Rompaey","doi":"10.15625/2615-9783/17374","DOIUrl":"https://doi.org/10.15625/2615-9783/17374","url":null,"abstract":"Coastal tourism includes diverse resources and activities, so a comprehensive assessment is required to implement the sensible use of tourism potential. This paper deals with a comprehensive assessment of tourism potential in the coastal region of Vietnam based on 4 dimensions: attractiveness, accessibility, tourism service quality, and environmental quality & safety, covering 23 criteria. Analysis Hierarchy Process (AHP), Principal Component Analysis (PCA), Correlation analysis, and a Geographic Information System (GIS) were used in this study. AHP was applied to determine a weighting coefficient for each criterion. PCA was processed next to AHP, allowing a combination of the considered sites' internal and external tourism potentials. Then the relationship between tourism potential and revenue is tested based on correlation analysis. The results show that the provinces in the South-Central region have the highest potential for coastal tourism development, followed by the North Central region. The Northern and Southeast region provinces and Mekong River Delta have low potential. However, there are still some bright spots for coastal tourism development in these regions, such as Quang Ninh, Ho Chi Minh City, Ba Ria-Vung Tau, and Kien Giang. This research also shows that tourism revenue depends more on external factors (supporting factors) than internal factors (tourism resources). Finally, the study proposed development plans for each group of coastal provinces based on their strengths and weaknesses, as well as suggested solutions to overcome the limitations of seasonality and the impact of climate change on Vietnam's coastal tourism.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43872076","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}

{"title":"Surface ruptures and land deformation from the 21 June 2022 Afghanistan earthquake","authors":"Khac Dang Vu, Trinh Phan Trong, P. Tapponnier","doi":"10.15625/2615-9783/17258","DOIUrl":"https://doi.org/10.15625/2615-9783/17258","url":null,"abstract":"The 2022 Afghanistan earthquake occurred at the border between Afghanistan and Pakistan at 20:54:36 (UTC) on June 21, 2022. According to the USGS, the earthquake caused vibrations with a magnitude of 5.9, a hypocenter located at a depth of 10 km, and an epicenter at 33,092°N, 69,514°E.  According to European Civil Protection and Humanitarian Aid Operations, this event resulted in disaster for human beings 1039 people died, 2949 people were injured, and damaged to homes and infrastructures of 4500 houses were partially or fully destroyed across Paktika and Khost provinces. It is necessary to improve the knowledge of this phenomenon. On the one hand, it is essential to quickly determine the extent of the affected area to provide timely relief services. \u0000On the other hand, it is necessary to determine the deformation characteristics of the fractured zone caused by earthquakes to minimize future damages. Conventional DInSAR technique applied to two images captured on June 18, 2022, and June 30, 2022, respectively, before and after the earthquake event shows the fractured zone with a maximum displacement of 78.4 cm, which locates on the left side of the previously identified northeast–southwest fault. The location of this zone is 15 km in the southward direction of the earthquake epicenter. The interferometric fringes show that a large area to the East of the study area is displaced in comparison to the original position. However, its Northwest region, which corresponds to the Paleogene formations, is much less affected by earthquakes. The earthquake occurred along a left lateral strike-slip fault in the plate boundary between India and Eurasia plates at the Northwestern margin of the collision.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49442018","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}

{"title":"Automatic earthquake detection and phase picking in Muong Te, Lai Chau region: an application of machine learning in observational seismology in Vietnam","authors":"Nghia Nguyen Cong, Duong Nguyen Van, Giang Ha Thi, Van Dinh Quoc, Minh Nguyen Le, Bor‐Shouh Huang, Truyen Pham The, Hung Nguyen Tien, Khoi Le Quang, Hung Nguyen Huu","doi":"10.15625/2615-9783/17253","DOIUrl":"https://doi.org/10.15625/2615-9783/17253","url":null,"abstract":"We applied the automatic detection and picking of P- and S-wave to one-year continuous raw seismic data from 17 seismic stations in the Muong Te area, northwestern Vietnam. The deep learning picker, Earthquake Transformer, has performed automatic picking of P- and S-waves, and phase association, then we located the earthquakes using Hypoinverse and NonLinLoc programs. The newly derived catalog consisted of 893 events, which is significantly higher than the number of events in the manual catalog. From this new catalog, we can observe more earthquakes related to the Muong Te ML 4.9 earthquake on June 16, 2020, and the earthquake activity in other faults such as the Dien Bien Phu and Muong Nhe faults. The extended catalog can further study the seismogenesis and the seismic velocity structure of the crust beneath northwestern Vietnam.","PeriodicalId":23639,"journal":{"name":"VIETNAM JOURNAL OF EARTH SCIENCES","volume":" ","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43299087","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}