DSpace collection: 期刊論文

Toward the next generation of research on earthquake-induced landslides: Current issues and future challenges

title: Toward the next generation of research on earthquake-induced landslides: Current issues and future challenges abstract: Although, thanks to the new developments in investigation techniques, modeling, and data analyses, much progress has been made in our understanding of collateral seismic hazards, important new lessons are still being learned from historic and recent earthquakes. By referring to the accompanying papers included in this Special Issue and other recent literature, we present an overview of current issues and future challenges of research on earthquake, triggered landsliding. We also offer some recommendations for future research priorities, as a proposed starting point for the next generation of research on earthquake-induced slope failures. These include i) the compilation of many more complete seismic landslide inventories with adequate contextual information, as well as of retrospective inventories; ii) the improvement of regional-scale assessments of seismic landslide susceptibility and hazard; iii) the development of new methods for regional scale analysis of hazards from large catastrophic landslides; and iv) the long-term monitoring of representative test slopes instrumented with an array of accelerometer stations. (C) 2011 Elsevier B.V. All rights reserved.

The formation and breach of a short-lived landslide dam at Hsiaolin village, Taiwan - part I: Post-event reconstruction of dam geometry

title: The formation and breach of a short-lived landslide dam at Hsiaolin village, Taiwan - part I: Post-event reconstruction of dam geometry abstract: In this paper, technologies from multiple disciplines are used to reconstruct the shape of the Hsiaolin landslide dam, a short-lived landslide dam (SLD), that was triggered by Typhoon Morakot Here, the formation, failure mode and breaching process of this SLD are investigated. The results indicate that the overtopping time and, the debris budget constrained the dam geometry. The inferred volume of the Hsiaolin landslide dam (15.4 million m(3)) is much smaller than the actual landslide volume (25.2 million m(3)) even considering the rock-mass dilation and debris entrainment. Meanwhile, a 46% error could be induced if an over-simplified equation (a function of the dam height, length and width) is used to calculate the dam volume. The saddle of the dam crest, which is where overtopping occurred, could be used as a reference to measure the dam height and length. Accordingly, the determined dam dimensions of height (44 m), length (370 m) and width (1500 m) are suggested to be the representative geometrical indices that influenced the stability of the Hsiaolin landslide dam. The flow rate of the dammed river, another variable relevant to dam stability, was determined from a run-off simulation. It is suggested that, instead of the peak flow before the dam formation, the flow rate during the blockage period (2974 m(3)/s) should be used as the training data for building a statistical model for stability predictions. Finally, the low hydraulic gradient at the toe of the dam's surface and the high safety factor of the dam slope indicate that the piping and slope instability were irrelevant to the failure of the Hsiaolin short-lived landslide dam. It is postulated that overtopping (about one hour after the blockage) dominated the failure process of this heavy-rainfall-induced landslide dam. (C) 2011 Elsevier B.V. All rights reserved.

Structure and Holocene evolution of an active creeping thrust fault: The Chihshang fault at Chinyuan (Taiwan)

title: Structure and Holocene evolution of an active creeping thrust fault: The Chihshang fault at Chinyuan (Taiwan) abstract: We conducted a variety of measurements and analyses at Chihshang Active Fault Observatory in eastern Taiwan, including surface-rupture mapping, three shallow borehole core analysis and kinematic analysis of geodetic measurements. We found that the Chihshang fault exhibits a three-branch fault system in the Chinyuan alluvial fan, which is composed of at least 100 m thick gravel deposits. Outside of the Chinyuan River, the Chihshang fault shows a single fault system with a sharp lithological contact. Combining the leveling results and trench excavation, we interpret that the three fault branches are coupled with a 50-60-m-wide pop-up structure in the hangingwall. Based on the ratio between vertical and horizontal displacements, we obtained dip angles of 38 degrees, 62 degrees and 16 degrees for two west-vergent thrusts and an east-vergent backthrust, respectively. This pop-up was estimated to develop at the uppermost 30-40 m unconsolidated gravels during the last few thousand years above the main fault with a dip angle of 42 degrees. By compiling the available ages data, we obtained an uplift rate of 2.3 cm/yr of the Chihshang fault and an alluvial sedimentation rate of 1.1 cm/yr during the past thousands years. Consequently, the individual uplift rate for each fault branch at the Chihshang Observatory was slightly less than the deposition rate of the Chinyuan River. No geomorphic fault scarp can thus be observed in the three-branch fault system area. (C) 2011 Elsevier Ltd. All rights reserved.

Response spectral attenuation relations for shallow crustal earthquakes in Taiwan

title: Response spectral attenuation relations for shallow crustal earthquakes in Taiwan abstract: In this study, a local set of response spectral attenuation equations, developed for seismic hazard analysis in Taiwan, are introduced as an example for determining the local strong motion attenuation relationship for a region. Strong ground-motion data for shallow crustal earthquakes are obtained from the Taiwan Strong-motion Instrumentation Program (TSMIP). These data are used to establish peak ground acceleration (PGA) and response spectral acceleration (SA) attenuation equations taking into consideration both hanging-wall effects and site conditions. The obtained results show that the local set of attenuation equations gives significantly lower values of PGA and SA for structural periods shorter than 0.3 s as compared to a set of global relations obtained from international data. The SAs obtained for structural periods longer than 0.3 s are similar to those obtained for global sets. This indicates that developing a local set of ground-motion attenuation equations is necessary for more accurate prediction of ground motion values. (C) 2011 Elsevier B.V. All rights reserved.