Seismic hazard model for loss estimation and risk management in Taiwan

We developed a seismic hazard model for Taiwan that integrates all available tectonic, seismicity, and seismic hazard information in the region to provide risk managers and engineers with a model they can use to estimate earthquake losses and manage seismic risk in Taiwan. The seismic hazard model is composed of two major components: a seismotectonic model and a ground-shaking model. The seismotectonic model incorporates earthquakes that are expected to occur on the Ryukyu and Manila subduction zones, on the intermediate-depth Wadati-Benioff seismicity zones, on the active crustal faults, and within seismotectonic provinces. The active crustal faults include the Chelungpu fault zone, the source of the damaging M_W 7.6 Chi-Chi earthquake, and the Huangchi-Hsiaoyukeng fault zone that forms the western boundary of the Taipei Basin. The ground-shaking model uses both US, worldwide, and Taiwanese attenuation relations to provide robust estimates of peak ground acceleration and response spectral acceleration on a reference site condition for shallow crustal and subduction zone earthquakes. The ground shaking for other site conditions is obtained by applying a nonlinear soil-amplification factor defined in terms of the average shear-wave velocity in the top 30 m of the soil profile, consistent with the methodology used in the current US and proposed Taiwan building codes.     

Changing places: The role of sense of place in perceptions of social,environmental and overdevelopment risks

An increasing focus on place based planning and adaptation processes brings to the fore the importance of understanding the situated experience of social and environmental change. Populations do not respond uniformly to environmental and social change, and given that consensus is needed to successfully achieve inclusive adaptation it is important to understand how and why people are more sensitive to certain changes and risks over others. Using a sense of place lens, we investigate how an individual’s relationship with their property and their town shapes their sensitivity to a range of risks. To investigate this, we conducted a survey in towns in South Africa, UK and France (n = 707) to examine the relationship between multiple dimensions of sense of place with place-based risks. We find that relationship with place matters differently for perception of social, environmental and overdevelopment risk. In particular, we find that feeling safe in place correlates with reduced perceptions of social risks but increases the likelihood of perceiving environmental risk. The role of place in risk perception is stronger at the property scale than the town scale, and it is only at the property scale that place meaning is related to risk perception. Our findings contribute to theory on the subjective experience of place-based risks and has implications for how social and environmental change can be communicated and managed.     

A social-ecological network approach for understanding wildfire risk governance

Large wildfire events (e.g. >100 square km) highlight the importance of governance systems that address wildfire risk at landscape scales and among multiple land owners and institutions. A growing body of empirical work demonstrates that environmental governance outcomes depend upon how well patterns of interaction among actors align with patterns of ecological connectivity, such as wildfire transmission. However, the factors that facilitate or inhibit this alignment remain poorly understood. It is crucial to improve understanding of the conditions under which actors establish or maintain linkages with other actors with whom they are interdependent because of ecological linkages. To this end, we introduce the concept of “risk interdependence archetypes” based on the spatial configurations by which one actor (i.e. a particular organization) is exposed to risk via the actions of another actor. We then develop a set of hypotheses to explore how different sets of conditions associated with each spatial configurations of risk interdependence may shape the likelihood that an actor coordinates with another actor in ways that promote social-ecological alignment. We test these hypotheses using network analysis of a wildfire transmission network developed through simulation of wildfires over several thousand fire seasons and a governance network created from interviews with 154 representatives of 87 organizations involved in efforts to mitigate wildfire risk in the Eastern Cascades Ecoregion, USA. Results indicate that social-ecological alignment is more likely when actors have opportunities to influence forest management practices on ignition-prone lands that they do not manage themselves, and when actors bear greater responsibility for averting losses from wildfires that spread to lands they manage independently. Importantly, not all forms of risk interdependence increase the likelihood of alignment, implying that organizations have limited capacity for interaction and may prioritize certain risk mitigation partnerships over others. While the performance of risk governance systems may hinge on the alignment of social and ecological networks, our results suggest that alignment in turn may depend on actor-level strategies for interaction with other actors.     

Fulfilling the promise of participation by not resuscitating the deficit model

'Participation with publics' has been embraced in both government and academic literatures as a necessary but currently unrealized means of governing socio-environmental challenges. This near-universal embrace carries global significance. Long-standing efforts in the context of disaster risk reduction (DRR) provide an opportunity to consider how experts have positioned participation such that it can only fail to empower publics. Using interviews with risk managers, we demonstrate that they impose boundaries on participation via application of a deficit model (DM). Despite continuous calls to make governance more participatory, we explore how the boundaries imposed on participation persist because of how experts are expected to do risk management, and how experts understand their occupations. As a result, meaningful publics-experts interactions are bounded into impossibility. Following demonstration of the DM as the essence of how experts conceive experts-publics interactions, using experts' own suggestions for improving risk reduction, we suggest relationship building as a way of reinvigorating participation. We explore how disaster risk reduction grounded in relationships could overcome existing boundaries, offering an easily-applied reconceptualization for differentiating meaningful from superficial participation, as well as a viable alternative to prevailing participatory methods. Given the intransigence of countless socio-environmental challenges and the need for improved interactions amongst experts-publics, the findings offer a novel pathway that may open an avenue to realizing the promise of participation.     

A qualitative risk assessment for the impacts of climate change on nationally and internationally important geoheritage sites in Scotland

Climate change is a significant concern for nature conservation in the 21?st century. One of the goals of the 2014 Scottish Climate Change Adaptation Programme is to identify the consequences of climate change for protected areas and to put in place adaptation or mitigation measures. As a contribution to the process, this paper develops a methodology to identify the relative level of risk to nationally and internationally important geological and geomorphological sites in Scotland from the impacts of climate change. The methodology is based on existing understanding of the likely responses of different types of geosite to specific aspects of climate change, such as changes in rainfall, rising sea levels or increased storminess, and is applied to assess the likelihood of damaging impacts on groups of similar geoheritage features in sites with similar characteristics. The results indicate that 80 (8.8%) of the ～900 nationally and internationally important geoheritage sites in Scotland are at ‘high’ risk from climate change. These include active soft-sediment coastal and fluvial features, finite Quaternary sediment exposures and landforms in coastal and river locations, active periglacial features, sites with palaeoenvironmental records, finite or restricted rock exposures and fossils. Using this risk-based assessment, development of indicative geoheritage climate-change actions have been prioritised for these sites. Depending on the characteristics of the sites, management options may range from ‘do nothing’ to rescue excavations and posterity recording. Monitoring is an essential part of the management process to trigger evidence-based interventions.     

Risk analysis of fractured rock mass underground structures

Recent accidents in underground structures have raised the risk awareness of the geotechnical engineering community. Geotechnical design is subject to significant uncertainties in load and strength parameters as well as in engineering models. However, engineering models which objectively address such uncertainties in design are still scarce. This paper presents an objective framework for the quantification of the risks involved in underground structures excavated in fractured rock masses, where structural failures may occur due to block falls. The framework considers the structure as a distributed system, where falling block probabilities are integrated over the main structural dimension. Random block size and geometry, arising from random joint orientation, are taken into account, as well as uncertainties in joint strength and geometrical parameters. A cost function is used to quantify failure consequences in terms of the block size. The framework is demonstrated in an application to a case study involving a real structure: the Paulo Afonso IV power station cavern. Results of the case study show that the studied cavern presents high reliability and very low risk. The framework proposed herein is shown to be a practical tool for the risk evaluation of underground structures constructed in rock masses, such as caverns and tunnels.     

凉山州夏季旱涝急转及典型年份大气环流特征研究

摘要：利用1961-2020年凉山州17个站点6-9月的逐月降水资料和NCEP/NCAR再分析月平均格点数据,定义了凉山州夏季长周期旱涝急转指数（LDFAI）,并对旱涝急转典型年份的大气环流特征进行分析。结果表明：1961-1970年为明显的LDFAI高值年,旱转涝年多于涝转旱年,且旱转涝强度较强;2001-2010年为明显低值年,旱转涝年少于涝转旱年,前期旱涝急转程度较强,后期旱涝急转程度很弱。涝期,高空西风带强度偏弱,中高纬槽脊更为显著,经向运动较强,有利于冷空气南下,中低纬为多波动纬向环流,凉山州上游短波系统活跃,高原多短波低槽东移影响凉山州,副热带高压位置适中,西脊点位于25°N、120°E附近,有利于孟加拉湾及南海的水汽向凉山州输送,水汽通道条件优于旱期,同时低层辐合、高层辐散的配置更明显,更利于上升运动,旱期则相反。凉山州旱转涝年的前期比涝转旱年的前期下沉运动更强,水汽辐合弱,不易产生降水,而旱转涝年的后期比涝转旱年的后期上升运动更强,水汽辐合强,有利于降水的产生。     

Early detection of brine and CO2 leakage through abandoned wells using pressure and surface-deformation monitoring data: Concept and demonstration

In this paper, we develop a methodology for early detection of potential CO₂ leakage from geological storage formations using pressure and surface-deformation anomalies. The basic idea is based on the fact that leakage-induced pressure signals travel much faster than the migrating CO₂; thus such anomalies may be detected early enough for risk management measures taking effect in avoiding substantial CO₂ leaks. The early detection methodology involves automatic inversion of anomalous brine leakage signals with efficient forward pressure and surface-deformation modeling tools to estimate the location and permeability of leaky features in the caprock. We conduct a global sensitivity analysis to better understand under which conditions pressure anomalies can be clearly identified as leakage signals, and evaluate signal detectability for a broad parameter range considering different detection limits and levels of data noise. The inverse methodology is then applied to two synthetic examples of idealized two-aquifer-and-one aquitard storage systems, with an injection well and a leaky well, for different monitoring scenarios. In Example 1, only pressure data at the monitoring and injection wells are used for leakage detection. Our results show that the accuracy of leakage detection greatly depends on the level of pressure data noise. In Example 2, joint inversion of pressure and surface-deformation measurements significantly improves the speed of convergence toward the true solution of the leakage parameters and enables early leakage detection. In both examples, successful detection is achieved when two monitoring wells are appropriately placed within up to 4 km from the leaky well.     

黄河流域旱涝年夏季蒸发计算及其变化

根据我国北方的热量平衡观测资料,地立了计算感热—潜热比的经验模式,用于计算黄河流域旱涝年(1972、1975、1986、1988年)及一般年(1971、1974、1985、1987年)夏季陆面蒸发,并分析其变化特点以及与旱涝的关系。