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Geology
Published in Ronald C. Chaney, Marine Geology and Geotechnology of the South China Sea and Taiwan Strait, 2020
The east–west profile of Taiwan Island as shown in Figure 2.13b consists of a coastal range composed of Miocene andesites and younger sedimentary rocks. Andesite is a gray volcanic rock of intermediate composition between basalt and rhyolite. The coastal range is a former island arc that can be linked to active andesitic islands off the south-eastern coast of Taiwan. Next along the east–west profile is the “long valley (longitudinal valley),” which is a prominent geomorphic feature. Further to the west in the central range are Pliocene clastics and Quaternary molasses. Holocene sediments cover the western Coastal Plain and foothills. In the north-south profile young andesitic volcanoes are found in the extreme north of the island. In addition, in the Miocene-Pliocene coarse-grained sandstone clastics is often found along with coal above North 23 latitude while rocks of the same age in the south are fine-grained and contain little coal, Wu and Chingchang (1991).
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Published in Eric W. Harmsen, Megh R. Goyal, Flood Assessment, 2017
The Río Guanajibo basin originates in the cordillera central of western Puerto Rico. It rises approximately 10 kilometers north-east of Sabana Grande at an elevation of 800 meters approximately. The topography of the area includes mountains, foothills and valleys. The Río Guanajibo valley is approximately 27 km long and is fan-shaped, with a width varying from approximately 0.6 kilometers in the area located between the town of Sabana Grande and San German, to approximately 5.2 kilometers in the Cabo Rojo and Hormigueros region, and approximately 2.8 kilometers in the valley outlet, near the mouth [23]. The Río Guanajibo basin is subdivided into subbasins for each principal tributary: Río Rosario, Río Duey, Río Cain, Río Cupeyes, Río Cruces, and Río Loco. The top of the Guanajibo valley lies in the east of Sabana Grande. In this area, serpentinite and volcanic rocks are predominant, in the south serpentinite predominates in a strip along the border. Rocks along the southern border of the valley near Punta Guanajibo consist of weathered serpentinite, with some volcanic-related rocks.
Measuring stiffness of soils in situ
Published in Fusao Oka, Akira Murakami, Ryosuke Uzuoka, Sayuri Kimoto, Computer Methods and Recent Advances in Geomechanics, 2014
Fusao Oka, Akira Murakami, Ryosuke Uzuoka, Sayuri Kimoto
The area of interest extends in north-south direction and has mountainous terrain in the north and low landfill areas towards the south. The alternative flat lowland areas and higher plateau exist in between Flat portion is divided into the foothills forming the mountain base and alluvial fan towards the city side. It extends about 3km in east-west and 5km in northsouth direction, and the altitude ranges from -2m to
The alteration of the suitability patterns of Leishmania infantum due to climate change in Iran
Published in International Journal of Environmental Health Research, 2021
In Region 3 of Iran (capital: Tabriz), generally high, 89–100% modelled suitability values can be seen. Although in the case of the later period of 2070, and the highest volume of emitted greenhouse gases (rcp 6, 8.5-based models), the area of the lower, 89–94% values are higher than in 2050 and rcp 2.6 and 4.5 scenarios, the climatic stability of Region 1 is not predicted to change notably for 2050 and 2070 compared to other regions of Iran. In Region 4 of Iran (capital: Kermanshah), which mainly covers the northwest ranges of the Zagros Mts. and the south-easternmost part of the Mesopotamian lowland, both the projected suitability values and their projected alteration compared to the reference period’s values are highly dependent on the altitude. In the Mesopotamian area around Ahvaz, the modelled values are between 62% and 72% for each period and scenario. In contrast, to Central Iran, the future possible effects of climate changes do not seem to be notable in this area due to the reference period’s already low suitability values. In the mid-elevation regions in the southwest foothills of the Zagros Mts., a milder, about −8% decrease in the suitability values is predicted for the future periods.
Groundwater contamination risk assessment based on intrinsic vulnerability, pollution source assessment, and groundwater function zoning
Published in Human and Ecological Risk Assessment: An International Journal, 2019
Yongsheng Zhao, Jiawen Zhang, Zhen Chen, Weihong Zhang
The aquifer is made up of pebble, gravel, and sandy and cohesive soil. From north to south, the medium changes from coarse to fine, the aquifer transforms from a single layer to multiple layers, and the rock thickness changes from thin to thick. There are large differences in the aquifer structure in the east-west direction. In the east, there is the rolling channel that is part of the main channel of Chaobai River, which has a wide aquifer, large particles, and high porosity. The study area is located in a warm, semi-humid continental monsoon area, and has four distinct seasons. Drought occurs in the spring. Conditions are windy, hot, and rainy in the summer but cool and humid in the autumn and cold and dry in the winter. Regional average annual rainfall is 656.5 mm. From 2004 to 2014, the average annual rainfall was 565 mm. With mountains on three sides of the study area and a plain to the south, the precipitation pattern shows certain changes. Precipitation is low in the mountains, foothills, and plain, and precipitation in the northern plains is greater than that in the southern plains.
Geotechnical Reconnaissance of the 2016 ML6.6 Meinong Earthquake in Taiwan
Published in Journal of Earthquake Engineering, 2018
Chi-Chin Tsai, Shang-Yi Hsu, Kuo-Lung Wang, Hsuan-Chih Yang, Wei-Kuang Chang, Chia-Han Chen, Yu-Wei Hwang
Figure 3 shows the topographical and geological maps of the Tainan area, with information on the active faults and the locations of the epicenters in recent disastrous earthquakes. The Tainan area can be divided into two main topographical regions, namely, the coastal plain and foothills. Different features of geological structure exist in these two regions. The coastal plain region exposes Holocene sedimentary deposits as its main feature. The Holocene sedimentary deposits consist of silt, clay, and sand with a thickness ranging from 16 to 36 m [Sun et al., 1964, 1970]. The relatively fine sediment is transported from the Central Range of Taiwan after the weathering of shale, slate, and mudstone. These soils are typical sedimentary materials of the southwestern plain of Taiwan. The rock formations beneath the sedimentary deposits are dominated by alternations of sandstone, mudstone, and shale. Conversely, the foothill region exhibits a more complicated feature because of the southward propagation of the oblique convergence between the Luzon Arc (the Philippine Sea plate) and the Chinese continental margin (the Eurasian plate). Therefore, the foothill region, located in the active fold–thrust belt of the Taiwan mountain range, would result in a high seismic hazard. The recent earthquakes, such as the 2011 Jiasain earthquake, 2012 Wutai earthquake, and 2016 Meinong earthquake, all resulted from the foothill region and caused considerable damage to buildings, lifelines, bridges, and levees.