Summary In response to global climate change, the government promotes energy transformation and 2050 net-zero emission policies. Under the forward-looking infrastructure plan, it plans to "enhance the comprehensive geothermal resource exploration and information supply plan", with the purpose of achieving energy transformation, creating green energy that the country will need in the future and promoting green energy infrastructure for environmental sustainability. The 2050 net-zero emissions plan is that renewable energy will account for 60–70% of total electricity in 2050. The short-term goal is to achieve low carbon, by reducing energy use and non-energy use carbon emissions, and carrying out energy transformation, increasing green energy, including geothermal energy. The long-term goal is to develop towards zero carbon, including the adjustment of energy, industrial structure and social lifestyle. Therefore, geothermal power generation, which can be used as base-load power, will play an important role in the future. The geothermal power plant development process includes: preliminary survey, resource exploration, drilling survey, feasibility assessment, site development, plant construction, and plant operation and maintenance (IGA Service GmbH, 2014). At this stage, the Central Geological Survey (CGS) is conducting basic exploration of geothermal potential areas, using emerging technologies to expand the scope and depth of exploration, so as to grasp the basic geological information of geothermal resources, and collect geothermal exploration data from various units to establish a geothermal exploration information platform. The CGS provides those who are interested in geothermal development to have access to underground geological information, so as to reduce the exploration risk in the early stage of geothermal development and shorten the development time. Starting from 2021, a key survey area “Ruilin-Hongye area” was selected for further exploration and investigation in many areas with geothermal potential in the Hualien area. In this project, the collection of past literature data and new survey data are integrated, and a conceptual model of geothermal geology in the Ruilin-Hongye area is initially proposed. Continuing with the measurement results of magnetotellurics in the key survey area, the volumetric evaluation method is used to evaluate the amount of geothermal resources.
Machine learning algorithms are commonly employed in landslide susceptibility assessments. Recently, algorithms that utilize artificial intelligence have come into prominence. This study attempts to adapt the most fundamental framework of deep learning and introduces fuzzy theory concepts to analyze landslide susceptibility while updating the network parameters with trial-and-error methods. The final analysis results will compare with those of logistic regression (LR). In order to assess the ability of the model to identify landslides in a more objective way, two typhoon events were used as a training event and a validation event, respectively. The results of the analysis show that the area under the curve (AUC) of the fuzzy neural network (FNN) for the training event is 0.915, but the AUC for the validation event drops to 0.746. Although the results of the FNN for training events were better than those of LR, they did not differ much from those of LR in predicting future events. The reason for this is that the difference between the landslide distributions of the training and validation events is too large, making the model biased in its identification. Overall, FNN is still a recommended method for analyzing landslide potential and can be used as a reference for LR.
The Lanyang Plain is prone to earthquakes of magnitude 5 or higher. The Central Geological Survey’s soil liquefaction potential map of Yilan County shows that more than 69% of the plain area has high liquefaction potential: but why have there not been any liquefaction cases in the past 23 years? Based on the results of the groundwater pumping test, geological history, and the soil liquefaction analysis method, this study aimed to explore and analyze the causes of no liquefaction occurring in the Yilan region. To understand the permeability of the overall stratum structure of the Lanyang Plain and the spring phenomenon, the relationship between groundwater well-pumping test results and the permeability coefficient experience formulas was first studied. Then the Chapuis’ experience formula of the K value multiplied by 10 was recommended herein such that the permeability coefficient K values of the Lanyang plain could be estimated with large numbers. The reasons for the absence of liquefaction cases in Lanyang plain were then investigated. It was found that less serious earthquakes occurred and combined with the extremely ideal permeable soil conditions existing in the Lanyang plain, this led to no catastrophic liquefaction cases occurring over the last 23 years.
A natural hillslope developing into a landslide shows ground cracks and topographic deformation. Geomorphological and subsurface investigations using appropriate methodology are essential to understand the failure mechanisms and stability of a hillslope. Huafan University campus located on a dip slope in northern Taiwan is facing a potential landslide hazard. Slope movement was detected through the development of ground cracks and persistent deformation of campus buildings and facilities. To monitor the sliding behavior of the dip slope, a nail network consisting of 144 ground monitoring points was set in 2001, and its coordinates were measured using conventional traverse surveying twice a year until 2017. The 17-year surficial surveying results were presented as a time series of displacements with constraints of geometry and distribution of ground cracks and underground observations. The long-term surveying results reveal multiple potential sliding blocks within the Huafan University campus. A model of landslide movement with a listric sliding surface is proposed. Additionally, from the velocity field derived from the monitoring points, the horizontal strain rates of the slope are estimated. The pattern of strain rates indicates that a plausible fault passing through the campus may have affected the movement of the dip slope. The long-term surface monitoring of a potential landslide slope in this study provides a reliable and economical way to understand the mechanism of movement behavior of the slope and evaluate slope stability.
To better characterize the vertical movements and the deformation behaviors across the plate suture of an arccontinent collision, we conducted annual repeated measurements on two precise leveling routes in a length of 34 and 37 km, respectively, across the middle part of the Longitudinal Valley in eastern Taiwan in 2004-2018. The 14-year-long results showed that the Longitudinal Valley fault (LVF) dominates the surface deformation: a) the middle LVF (Juisui fault) exhibited partially locked in the upper few kilometers, with a cumulative uplift rate of 9-10 mm/yr in a distance of 4 km; b) the southern LVF (Chihshang fault) showed a creeping behavior with a vertical rate of 24-27 mm/yr. In addition, we are able to characterize other features, including 1) tilting upward to the west in the eastern Central Range, suggesting activity on the west-dipping Central Range fault; 2) the hanging wall of the LVF showed tilting downward behavior to the east; 3) the Chimei fault, a suspected active fault, revealed active slip on the sub-vertical fault plane, that caused a vertical rate of 8-9 mm/yr. Putting the results under global ITRF system, the whole Juisui route was moving downward, supporting the notion that NNW subduction of the Philippine Sea plate starts around the latitude of the middle of the Longitudinal Valley. Finally, the co-seismic vertical deformation of the 2013 ML6.4 Juisui earthquake was characterized by tilting upward to the west, consistent with stick-slip on the deeper part of a west-dipping interface of the forearc basement.
