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Engineering risk assessment is to estimate the structure's failure probability multiplied by its failure consequences. On the other hand, the analysis was sometimes performed on a more general basis, utilizing a few indicators to quantify relative risk levels for decision-making. On the basis of such a framework, this paper introduces a novel risk assessment on 18 active faults in Taiwan, considering the fault's location, earthquake size and return period from the literature. The result shows that the Chelungpu Fault in central Taiwan has the highest risk score among the 18 active faults, in contrast to the Hengchun Fault in southern Taiwan which has the lowest risk. Besides this, the 18 active faults in Taiwan were classified into four groups based on this risk assessment, and the classification could help the region's sustainable development against earthquake hazard. [ABSTRACT FROM AUTHOR]

According to the Central Geological Survey Taiwan (CGST), the Meishan fault in Central Taiwan, which induced a catastrophic earthquake in 1906, is considered capable of triggering equivalent events with a return period of 162 years. Therefore, as the next event is expected around 2070, the Meishan fault poses a high level of earthquake risk in Central Taiwan, especially for those cities and townships very close to the fault. However, the best-estimate return period (162 years) and earthquake magnitude (7.1 M) reported by the CGST must be subject to some uncertainty, because such an event is very unlikely to recur every 162 years. Therefore, this study carried out a series of seismic hazard assessments for three major cities close to the Meishan fault, with the uncertainty of the best-estimate information being determined using the Rosenblueth algorithm. The results show that for Chaiyi city, which the Meishan fault passes through, the probability of the current design value (i.e., PGA = 0.33 g) being exceeded by the earthquake motion induced by the Meishan fault in the next 50 years would be as high as 55 %. Therefore, further studies should be carried out to obtain a better understanding of the Meishan fault, to develop a robust hazard mitigation plan for nearby cities. [ABSTRACT FROM AUTHOR]

The active fault traces on which earthquakes occur are generally not continuous, and are commonly composed of segments that are separated by discontinuities that appear as steps in map-view. Stress concentrations resulting from slip at such discontinuities may slow or stop rupture propagation and hence play a controlling role in limiting the length of earthquake rupture. Here I examine the mapped surface rupture traces of 22 historical strike-slip earthquakes with rupture lengths ranging between 10 and 420 km. I show that about two-thirds of the endpoints of strike-slip earthquake ruptures are associated with fault steps or the termini of active fault traces, and that there exists a limiting dimension of fault step (3–4 km) above which earthquake ruptures do not propagate and below which rupture propagation ceases only about 40 per cent of the time. The results are of practical importance to seismic hazard analysis where effort is spent attempting to place limits on the probable length of future earthquakes on mapped active faults. Physical insight to the dynamics of the earthquake rupture process is further gained with the observation that the limiting dimension appears to be largely independent of the earthquake rupture length. It follows that the magnitude of stress changes and the volume affected by those stress changes at the driving edge of laterally propagating ruptures are largely similar and invariable during the rupture process regardless of the distance an event has propagated or will propagate. [ABSTRACT FROM AUTHOR]