Dear Dariush Abolfathi, Dr Aghil Madadi, Dr Sayyad Asghari,
Volume 22, Issue 66 (9-2022)
Abstract
The purpose of this study was to estimate the amount of sediment of Vanai River in Borujerd. In this research, the characteristics of the sub-basins of this river have been extracted first. These specifications include the physical characteristics of the sub-basins, including the area, the environment and length of the waterways, and the characteristics of the river flow, and its sediment content. In the following, multivariate linear regression, multilevel prefabricated neural network (MLP) and radial function-based neural network (RBF) models are used to model sediment estimation. After estimating the model, the mean square error index (RMSE) was used to compare the models and select the best model. Evidence has shown that initially the MLP's neural network model had the best estimate with the lowest error rate (90.44) and then the RBF model (151.44) among the three models. The linear regression model has the highest error rate because only linear relationships between variables are considered.
Fariba Sfandyary Darabad, Mansour Kheirizade, Masoud Rahimi,
Volume 22, Issue 66 (9-2022)
Abstract
Floods are one of the most abundant and destructive natural disasters that every year are caused heavy losses of life and property. Due to human activity in river systems and construction in rivers, flood damage has an upward trend. One of the most important actions to reduce flood damage is the provision of flood hazard zoning maps and their use in spatial planning. In this study, the risk of flood in the Nirchay River Basin that located Ardebil province was investigated. For this purpose, the HEC-HMS model was used to simulate rainfall-runoff and to identify flood zones and fuzzy logic in order to overlay the layers and prepare a flood hazard zoning map.The simulation results show the high performance of the HEC-HMS model in simulating rainfall-runoff of the Nirchay River Basin and estimating peak flood discharges. Rainfall conversion to runoff at the Nirchay River Basin controlled by slope and land-use.The most runoff height and peak flow in Nirchay River Basin are located in the upstream sub-basins. This is due to the steep, low permeability soil, frequency impervious surfaces and high CN. The combination of layers using fuzzy logic has shown that about 8.6% of the surface of the basin are located with a high risk of flooding. These zones are located mainly on the floodplain of the Nirchay Basin. Due to the Low valley width and low slope, these lands are always at flood risk. Most settlements in the study area are located at downstream of the basin. This has increased the risk of flooding.
Mrs Malihe Mohamadnia, Dr Abolghasem Amirahmadi, Dr Mohamadali Zanganeasadi,
Volume 22, Issue 66 (9-2022)
Abstract
The purpose of this research is to use granulometric analyzes in desertification studies in Gonabad city, To achieve this goal, after the preparation of geomorphological maps of the region, 14 sediment samples were taken from the erosion-sensitive facies of the region. In the laboratory, a series of sieve with a diameter of 2000, 1000, 500, 250, and 64 micrometers, and a container Gatherings of sediment smaller than 64 μm were screened. The results showed that the highest frequency of particle diameter in sand samples was in the 250-225 micron class. And, given the average particle relationship with their transport intervals, it can be concluded that the distance between the particles was close to a point. Variants of different samples varied from 1.502 to 1.319. The most prevalent plots of ridge and the smallest slopes with low slope were the highest. In surveys in the skidding section, precipitates were mostly positive tilted, indicating the prevalence of fine particles in the region.
Ms Mehdi Kashefi, Dr Mojgan Entezari, Dr Maryam Jafari Aghdam,
Volume 22, Issue 67 (12-2022)
Abstract
vulnerability is considered as an inherent talent of underground water system that depending on the sensitivity of the system to anthropogenic effects. Natural vulnerability is based on the geomorphologic features of surface karst, type and level of aquifer recharge and hydrodynamic aquifer karstic aquifer in Fars province is the most important source of water supply for the supplement of drinking water of communities in the province, which are prone to pollution due to the natural conditions of the region and human activities. karstic aquifer of Shispir and Borghan plays a vital role in supplying drinking and agricultural water around them. The aim of this study is to estimate the natural vulnerability karstic aquifer of Shispir and Borghan using the proposed model of Cast action 620, and prioritize the level of aquifer in the field of conservation measures and provide management solutions in order to better protect them in this model. To prepare a natural vulnerability map are used geological maps, soil, vegetation, digital elevation model (10 meter) and precipitation statistics of meteorological stations and vulnerability map is evaluated as three factors of C, O, p. In the end, the region in terms of damage in five levels was classified in very high, high, low, low and very. The results of the COP model show the natural vulnerability of the region is high. In addition, the amount of vulnerability in the two upper and upper floors of this region is about 47 % where is the highest coverage area of that region of Shisper aquifer. The results of this study show the efficiency of the proposed methods by Cast Action 620 to detect and protection of groundwater resources from vulnerabilities and natural pollution.
Dr Amir Saffati, Dr Ezatallah Ghanavati, Mr Hamid Alipour Dezdouli Asl,
Volume 23, Issue 68 (3-2023)
Abstract
Studying the morphology of the rivers and identifying the causes of these changes are widely useful in determining the evolution of rivers and planning the maintenance of the river system. The Karun River, between Bandar-e-Khoramshahr and the constant flow of water in the country, plays an important role in the country's water cycle. Due to the morphological changes of this river that have disrupted the normal functioning of the river, it is necessary to investigate the morphological changes and its causes. In this study, with the aim of investigating these changes with satellite imagery, Landsat images for 1990, 2005 and 2018 were prepared and morphological changes were extracted after required processing. The results show that out of the 36 investigated sections, the width of the river has decreased in 29 sections so that it has narrowed to 450 m around Ahwaz. In order to investigate the causes of changes, the effective parameters in changes such as precipitation, discharge, runoff coefficient, waterway length, permeability coefficient, landform, lithology, land use change, wasteland, slope percentage, drainage density and vegetation density, land Theology and floodplains, To assess the hazards of the area, were used. Floodplain parameter was extracted using ANP_Fuzzy model and landslide and land use parameters were extracted using SVM model. Among the factors affecting these changes that were investigated using logistic regression models and factor analysis were land use changes, vegetation density and sediment yield. These changes have resulted in the destruction of natural habitats along the river, the ability to self-purify water, sudden floods, threatening and damaging human structures, agriculture, and so on.
Asadolah Hejazi, Zahra Heidari,
Volume 23, Issue 68 (3-2023)
Abstract
In recent years, population growth and consequently the shortage of drinking water resources have increased the importance of studying the areas of caries Regarding the importance of the subject, in the present study, the evaluation and monitoring of the developed karstic areas and the potential of contamination of Cartesian resources in the Ravensar basin have been addressed In this study, 7factors were used to evaluate the factors of Karst development in Ravansar basin as well as two methods of OWA and ANP. The method of work is that after the necessary processing, using the OWA method and applying weights obtained through the ANP model, the zoning is done After designing the zoning map, using the satellite imagery of 2007 and2015, the development of human development areas in the developed karstic areas has been evaluated The results of this study indicate that most of the studied basin, especially in northern and western areas of the basin, are highly and relatively developed in the class, The calculation of the area of man-made areas suggests that in2007, about 2.6 km of occupied areas of man-made industrial zones have been occupied which, according to the growing population, increased to 3.8 km in2015, human-made areas have been extracted in developed artisanal areas
Fariba Esfandiary Darabad, Morteza Gharachorlu,
Volume 23, Issue 69 (6-2023)
Abstract
This study was aimed at identification and determination the spatial variations of sediment yield in Qarasu watershed located in Ardebil province, NW Iran, considering the negative consequences of erosion and sediment yield. In this regard, the monthly time scale, as the basis of work, was used to prepare the sediment rating curves. Preparation of monthly sediment rating curves based on sample flow and corresponding sediment discharge data in 19 hydrometry stations at the watershed during 14 years (2002-2015). All of statistical analyses were done by SPSS statistical software. Also, presentation of spatial variations in sediment yield over the watershed were made possible through the capability of GIS. The results of regression relations between flow and sediment discharge showed a close and significant relationship on a monthly time scale. The regional generalization of these relations for the whole basin showed that the seasonal difference was evident and the highest and lowest coefficient of determination was allocated to May (R2 = 0.74) and August (R2 = 0.55), respectively. Also, the highest and lowest sediment transport was observed in spring and summer, respectively, indicating the type of rainfall-runoff regime dominated on Qarasu watershed. In terms of the annual sediment yield, Yamchi station with 3970 tons per year and Nanakaran station with 66 tons per year, have the highest and lowest sediment yield among 19 stations of Qarasu watershed, respectively. According to the high levels of sediment yield in the Balikhly and Khyav sub-watersheds, it was recommended that more attention be paid to protecting and strengthening the water and soil elements and reducing the driven forces of erosion and sediment production in these sub-watersheds.
Sara Kiani, Dr. Amir Karam, Ms Nasrin Hoseinaei,
Volume 23, Issue 70 (9-2023)
Abstract
The Kan-Soleghan basin is located on the southern Hillside of the Alborz, which has affected the Alp-Himalayan active zone over time. In this respect, the evaluation of active tectonic processes and their effects on many human activities, such as the design and construction of cities, powerhouse, dams, and industrial facilities are of great importance. The passage of the Tehran-North Freeway Tunnel from the area increases the activity of the faults that contributed to the formation of the current morphology of the basin. In this research, morphotectonic indices including river asymmetry index (Af), basin shape (Bs), hypsometric integral (Hi), Stream length index (Sl), mountain front sinusity (Smf), valley width to valley height (Vf), topographic symmetry (Tp) was calculated. Finally, the mean of the results of the indices was calculated as the LAT index. In the present study, topographic Map 1:50000 and digital elevation (DEM) maps with 30 m spatial resolution (ASTER sensors), the boundary layer of the basin, were used to calculate morphometric indices. The Kan-Soleghan basin area is divided into three tectonic regions with slow, semi-active, active Tectonic, and the calculation of the relative active tectonic (LAT) index indicates that the studied area is in tectonic terms in active state. The tectonic structures, especially the faults of the region, have affected the asymmetry and shape of the basin. The main river Kan-Soleghan also shows asymmetry, which can be said due to the structural factors, especially the faults of the region, the basin has asymmetry and deviation to the left of the basin. Also, the construction of the Tehran-north freeway and the location of the Tunnel openings in the vicinity of the northern fault of Tehran, is one of the human factors influenced by the tectonic activity of the area, which requires tectonic activity.
Abolghasem Amir Ahmadi, Leila Goli Mokhtari, Naemi Tebar Mahnaz,
Volume 23, Issue 70 (9-2023)
Abstract
The purpose of this study was to identify evidence of late Quaternary glaciers in the northern highlands of Binalood. Topographic maps, satellite imagery and climatic data are the tools and data used in this study. Arc gis 10.4 software was used for data analysis. Quaternary glacier evidences were identified based on four types of evidences including morphic indices, climatic evidences, geomorphological evidences and laboratory indices. Using morphic indexes, the curve lines were identified on topographic maps of satellite imagery, ice-dominated areas, and the effects of 28 glacial circuses. Climatic evidence shows that not only was Quaternary at about 7 degrees cooler than the present time, but its precipitation was almost twice as high as at present. On the other hand, glacier circles, moraines, thales and glacial mounds were the most prominent geomorphologic evidence of glaciers in the Binaloud Heights. Finally, granulometric laboratory indices supplementing the evidence of glaciers have confirmed the existence of glacial sediments at the Binaloud Heights. Also, using Wright's method, the permanent snow boundary line during the reign of Binalood Heights Glaciers was estimated at 2600 m.
Mr Abazar Solgi, Dr Heidar Zarei, Dr Safar Marofi,
Volume 24, Issue 72 (3-2024)
Abstract
Different methods are used for baseflow separation, filtering method one of these methods. In this study, the filtering methods with different algorithms, inclusive One-Parameter, Two-Parameter, Three-Parameter, Lyne & Hollick, Chapman, Furey & Gupta, Eckhardt and Ewma used for daily baseflow separation of Kahman karst spring in Aleshter county. The statistical period used in this study was a period of 27 years. The Isotope content method used as the main method for baseflow separation. Samples analyzed at the Mesbah Energy Company laboratory. Each algorithm has different parameters. First the parameters of each algorithm optimized based on the isotopic content method in the water year of 2017-2018. Then the optimized parameters used for the period 27 years. At the end, using the evaluation of different critical compared to the different algorithms. The results showed that the Eckhart algorithm performs better than other algorithms. This algorithm estimated baseflow and surface water indexes, respectively 81 and 19 percent.
Dr Raoof Mostafazadeh, Dr Fariba Esfandiary, Miss Mahnaz Hamzeei, Miss Nazila Alaei,
Volume 24, Issue 72 (3-2024)
Abstract
The purpose of this study was to evaluate the temporal variations of vegetation cover of Gharesou River riparian area in Ardabil province using landscape metrics over a period of 8 years which is important for morphology assessment and river ecosystem protection planning and management. The Google Earth imagery for the years 2011, 2016, 2019 due to their live view and high resolution were used to map the Gharesou River riparian area vegetation. Correlation analysis in R environment was used to evaluate the relationship between landscape metrics in the study time period. The results showed that there is an increase in the number of patches, which showed an increase in landscape fragmentation of the riparian area vegetation. Landscape connectivity index was 91.52% to 95.49% in this region during the study period, indicating the removing small patches of vegetation communities around the river. The number of patches in the present study showed an increasing trend, which was the highest amount at 2019 year. The results of changes in the width of the Gharesou River showed that the river width in 2019 was 27.43m and 3.97 m, respectively. Comparison of river width values over the three study periods indicates an increasing trend in river widths, which may be due to the limitation of river width by human activities or the protection of river banks to protect agricultural lands against flooding effect. Also, the correlation of river width showed that the correlation between time period 2019 and 2016 was 0.63 and significant at 0.001 levels. The lowest correlation between the period 2019 and 2011 was 0.30 at 5% significant level. In conclusion, the results of changes in riparian area communities can be linked to the extension of agricultural land adjacent to the main river course.
Roghayeh Delaram, Samad Fotohi, Mohsen Hamidianpoor, Morteza Salari,
Volume 24, Issue 72 (3-2024)
Abstract
The subsidence phenomenon is considered one of the most frequent hazards occurring worldwide and imposing irreparable damages every year. This phenomenon affects the ground’s surface and its layers and causes the ground deformation. It can be referred to as a morphological phenomenon that is associated with the gradual sinking of the ground and the vertical movement of materials. Among the various methods used to study the land subsidence pattern, the Differential Interferometric Synthetic Aperture Radar (DInSAR) technique has provided more accurate results. Therefore, this technique was used to investigate the subsidence rate in Mashhad plain from 2003 to 2010 and the Envisat ASAR (C-band) and Sentinel-1 ASAR (C-band) satellite images were employed during the year 2019. The results show that the highest subsidence rate of about 44 cm occurred in Qasem Abad and Kalateh-ye Barfi lands from 2008 to 2010. A subsidence rate of about 37 cm was also observed in the same area from 2007 to 2009. The interpolation results using piezometer well statistics show a decrease in groundwater levels in this area and confirm the accuracy of the results.
Dr Esmaiel Najafi, Dr Amir Safari, Dr Ezatoalah Ghavavati, Dr Amir Karam,
Volume 24, Issue 73 (6-2024)
Abstract
Geomorphology is related to the processes and forms of the earth's surface, and any human activity, including the construction of bridges, leads to quantitative and qualitative changes in the movement and displacement of materials and kinetic energy and affects the geomorphic system, is the concern and involvement of geomorphologists. Geomorphology, as a systematic science can also study and explain the environmental realities that have been objectified in the form of processes and forms in nature, and introduce their results and output spatially in the form of maps and models. The type of research is applied and the research method is descriptive-analytical and based on the results of the Ph.D. Thesis entitled "Geomorphological modeling of the construction of bridges in urban floodways (Case study: Tehran metropolis)". The results indicate the capability and application of geomorphology in modeling and optimal location and construction of bridges, in order to create more security and welfare of citizens, reduce costs and prevent financial and human losses due to the destruction and improper location of such structures in an urban floodway- river valleys and other natural environments. Also, this study, while enriching the literature of the field in question, has studied, explained, and conceptually modeled the role and application of geomorphology in the optimal location and construction of bridges in urban issues.
Keywords: Geomorphology, Conceptual Model, urban floodway- river valleys, Bridge Construction.
Zahra Heidari, Asadolah Heqazi, Shahram Rostaei, Siros Fakhri,
Volume 24, Issue 74 (9-2024)
Abstract
Given Iran's ongoing role in the Middle East and the constant threat of external threats, it is imperative that I take action on the critical and important steps of my country Of the measures that can prevent the occurrence of malignancies , Kermanshah region due to its geographical location and proximity to Iraq as well as its complex morphology include high mountainous lands, relatively wide valleys and plains, geological structural diversity and With the immediate approach, Identify these natural features It creates the right places With passive defense approach To establish these centers. In this research, the research tools are surveyed topographic maps, geology and satellite and aerial images of the area as well as interviews with experts identifying the effective factors in locating critical and important centers with emphasis on passive defense..And after identifying them using AHP (Multi Criteria Decision Making Models) in order to compare the criteria has been analyzed. Also according to the final map based on geomorphological factors in ARC- GIS software environment The area of optimum area for the location of critical and sensitive areas in the northern part is greater than the soothe In other words, the geomorphologic features of the region in the northern and eastern parts of the region are more favorable than those in the western and southern regions for the optimal location of sensitive and important sites.
Sayyd Morovat Eftekhari,
Volume 24, Issue 74 (9-2024)
Abstract
One of the consequences of the earthquake can be changes in the elevation levels of the unevenness in the area of occurrence. These changes at the level of the region will not be the same and the amount will be different under the influence of several factors such as: earthquake intensity, landforms, geo-material, and structure geological... The purpose of this research is to measure the geomorphometric changes caused by the earthquake of 17th February 2021 at the level of Dana County using the radar technique differential SAR Interferometry. To achieve this goal, taking into account the appropriate coverage and measurement accuracy of the Sentinel 1 radar satellite images from two image scenes related to the earthquake area for the dates before (2021.02.08) and after the earthquake (2021.02.20) from the organization's website. European Space Agency (ESA) was received, after performing the process and data analysis Differential Synthetic Aperture Radar Interferometry (D-InSAR), it was found that after the earthquake dated 2021,02,17, a part of the studied area was affected by positive elevation changes with a rise of 0.11 cm and Negative changes of -0.6 cm subsidence have been encountered. These positive changes (uplift) are more noticeable near the epicenter of the earthquake in the east of Dena, and the negative changes (subsidence) are quite evident with the Syncline Valley on which Khorasan Rivers is located. And in dealing with the faults, changing the geological structure, geo-material of the region, it has a special irregularity.
Dr Mohammad Ebrahim Afifi,
Volume 24, Issue 75 (12-2024)
Abstract
Among the natural hazards, without a doubt, the flood is known as a natural disaster. In this research, Shannon entropy model was used to prepare a flood sensitivity map. First, 34 flood watersheds were selected from Firoozabad basin, and then these 34 points were classified into two groups. With 22 points, 65 percent of the points for training and modeling, and 12 points, 35 percent of the locations that were not used in modeling were used for validation. First, a map of the status of the floods was developed and Then, 10 factors, slope, tilt, lithology, land use, NDVI, SPI, TWI, altitudes, rainfall and distances from the river were selected as flood factors in Firoozabad basin. Prioritizing the effective factors in the occurrence of flood by Shannon entropy index showed that the NDVI layers (2.03), rainfall (0.00), distance from the river (1.89), SPI (385.1), elevation classes (999 (0/19), gradient with weight (0,932), lithology (478/0), TWI (379/0), and land use (280/0), respectively (0/184) have the highest and the least impact Flood events. Based on the results of the ROC curve, the predicted surface area under the curve with 35% of the validation data is equal (91.42%) and for the success rate with 65% of the equal education data (92.53%).
Mrs Zeinab Karimi, Sir Davood Mokhtari,
Volume 24, Issue 75 (12-2024)
Abstract
Rivers are environmental forms that react strongly to changes in their bed, tectonic is the most important factor affecting morphology of the river, causing significant changes in river systems. In this study, using the digital elevation model (DEM), Geographic Information System (GIS) and Global mapper 13, we investigated the effect of tectonic activity on river systems in the eastern slopes of Mullah Daghi, southeast of Zanjan province, this The area is drained by Abhar river. Using the Digital Elevation Model (DEM) in the Arc Gis 10.2 software environment, required maps including geological maps, topography and…, Geological map of 1: 250,000 leaves of Zanjan was used to prepare the fault map. In order to achieve the research objectives, tectonic activity indicators including: are Mountain front sinuosity, basin shape, drainage density, longitudinal gradient of the river, River maze, basin asymmetry, hypersometric integral, the topographic symmetry of the basin and the width of the valley floor to the height. The combination of these indicators is achieved by the tectonic activity index (IAT). The results obtained through the Iat index indicate the activation of tectonic and neotectonic in the watershed of Ardejin and Abhar and the moderate activities in the basin of the zareh bash basin. The impacts of these activities on river systems that are different from the tectonic indexes in the studied basins, such as river meanders(main stream), coniferous formation (Ardejin watershed basin), tilt watersheds abhar and Ardejin and the shape of the basins (Basin elongation zareh bash)
Mrs Negar Mirzaii, Dr Ali Ahmadabadi, Dr Seyed Morovat Eftekhari, Mrs Elaheh Lofti,
Volume 24, Issue 75 (12-2024)
Abstract
Rivers are always vital arteries of the earth and naturally, they have a gradual and continuous development process which has undergone fundamental changes after the expansion of human settlements and urban development and they have lost some of their natural functions. Wardvard River is no exception to this. This river flows in the west of Tehran province and has been heavily affected by urban development which has undergone continuous changes in its flow path due to human interference and considering that this river flows in the access route of western cities of Tehran province, its natural and gradual evolution has been disrupted that this transformation, it has removed the river from its natural condition. In this research, the factors affecting the geomorphological quality of Wardvard River have been identified and using MQI index, it had evaluated the quality of river morphology. In this method, Wardvard River is divided into 9 study periods and the three main components of the quality of geomorphological performance, artificial structures and channel adjustment have been evaluated in the form of 28 indicators. Results show due to the urban development of Tehran and many artificial changes in the Wardvard river channel, intervals 1, 3, 4, 6, 7 have earned a score of 0.2 due to human interference and canalization of the river and it is very poorly placed on the floor.Intervals 2 and 5 have earned 0.3 points and it is placed in the weak class and intervals 8 and 9 have scored 0.6 due to the low human interference and the natural course of the river and it is placed in the middle class in terms of morphological quality.
Mr Arsalan Mehrvarz, Dr Agil Madadi, Dr Fariba Esfandyari, Mr Masoud Rahimi,
Volume 25, Issue 76 (3-2025)
Abstract
River morphology holds significant importance in the fields of geomorphology and river management and engineering. The marginal sections of rivers have consistently undergone changes in their riverbeds due to various social and economic factors. The Dare Ourt River, located in the Ardabil province, represents a permanent river that has experienced frequent floods and alterations in its channel morphology in recent periods. In this study, the Dare Ourt river was thoroughly analyzed using the Rosegen model at levels one and two. To conduct this study effectively, detaied data such as 1:2000 river topographic maps, hydrometric data, and boundary conditions from the Ardabil Regional Water Authority were collected and utilized. Furthermore, the HEC-RAS hydrodynamic model was employed to extract the primary indices of the Rosegen model with greater accuracy. The outcomes revealed that the majority of the river sections exhibit a C6c type, characterized by an alluvial substrate. Additionally, other dominant types observed within the four examined ranges include B6c, E6b, F6, and D. Field visits also confirmed a transition in the river type from C to F within range 4, which presents challenges for the reconstruction and restoration of the river in type F. As a recommendation, it is advised to implement restrictions to prevent the river from transitioning into type F.
Dr Esmaeil Najafi, Mr Abolfazl Faraji Monfared, Dr Mehdi Ahmadi,
Volume 25, Issue 76 (3-2025)
Abstract
The extent of mountainous and desert areas in Iran has caused the emergence of well-known geomorphological phenomena. Alluvial fans are landforms found in various locations. Identifying and evaluating their impacts can be valuable for natural hazard management and land use planning. In this study an attempt hs been made to evaluate the status of tectonic activities in the south of the slopes of the Kharqan mountain range in the northeast of Hamedan province. Different maps were utilized to examine the development process of alluvial fans and present evidence of tectonic activity, including the Gozal Valley, Karafs, and several smaller alluvial fans. The findings of this study revealed that tectonic activity in the Gozal Valley cone remains active, while the alluvial fans located between the Gozal Valley are inactive. Further evidence in the bed of the Gozal Valley cones suggests tectonic changes caused by fault activity, resulting in the alteration of the riverbed's drainage pattern and subsequent destruction and erosion of the surrounding areas. Additionally, changes in drainage patterns and sediment depth on the surface of alluvial fans can be attributed to tectonic activities within these fans. Geological logs illustrate both prolonged, slow periods and active periods during various geological eras in the study area. Ultimately, tectonic activity initiated with a lengthy, sluggish phase, followed by continued tectonic activities and fluctuations.
