DSpace collection: 期刊論文

Surface deformation from persistent scatterers SAR interferometry and fusion with leveling data: A case study over the Choushui River Alluvial Fan, Taiwan

Tue, 27 Mar 2012 09:37:00 GMT

title: Surface deformation from persistent scatterers SAR interferometry and fusion with leveling data: A case study over the Choushui River Alluvial Fan, Taiwan abstract: The Choushui River Alluvial Fan (CRAF), one of the most important agricultural areas in Taiwan, suffers severe subsidence caused by groundwater withdrawal. We use 20 ENVISAT images from 2006 to 2008 to derive vertical deformation over CRAF by persistent scatterer interferometry (PSI), which effectively reduces errors affecting conventional DInSAR techniques. The pixel density over CRAF is 107.6 pixels/km(2), compared to 0.19 points/km(2) of the leveling benchmarks. PSI yields vertical displacements matching the leveling result to 0.6 cm/year (RMS), and provides a higher spatial resolution of subsidence than the latter. We also develop a data fusion method that considers the high-precision, low point-density leveling result as a smoothed correction to the PSI result. The combined field is more representative of overall deformation characteristics than the PSI-only or leveling-only field, and it is better suited for the assessment of the impact of subsidence over CRAF. (C) 2010 Elsevier Inc. All rights reserved.

Statistical physics of landslides: New paradigm

Tue, 27 Mar 2012 09:36:57 GMT

title: Statistical physics of landslides: New paradigm abstract: We suggest an innovative distribution function of landslide sizes, based on the non-extensive Tsallis entropy. Our result incorporates the characteristics of non-extensivity of fragmentation into the cumulative distribution of landslide sizes. Such an approach can lead to a groundbreaking statistical physics of landslides. Copyright (C) EPLA, 2011

Sedimentlogy of early Pliocene sandstones in the south-western Taiwan foreland: Implications for basin physiography in the early stages of collision

Tue, 27 Mar 2012 09:36:55 GMT

title: Sedimentlogy of early Pliocene sandstones in the south-western Taiwan foreland: Implications for basin physiography in the early stages of collision abstract: This work presents sedimentological observations and interpretations on three detailed sections of the Pliocene Yutengping/Ailiaochiao formations, deposited in the early stages of collision in Taiwan. Seven facies associations record paleoenvironments of deposition ranging from nearshore to lower offshore with a strong influence of tidal reworking, even in shelfal sub-tidal environments, and a pro-delta setting characterized by mass-flows. The association of shallow facies of the upper offshore to lower shoreface with pro-delta turbidite fades sourced in the orogen to the east suggests a peculiar setting in which turbidite deposition occurred below wave base but on the shelf, in water depths of probably less than 100 m. This adds to the examples of "shallow turbidites" increasingly commonly found in foreland basins and challenges the classical view of a "deep" early underfilled foreland basin. Time series analysis on tidal rhythmites allow us to identify a yearly signal in the form of periodic changes of sand-supply, energy and bioturbation that suggests a marked seasonality possibly affecting precipitation and sediment delivery as well as temperature. The Taiwan foreland basin may also present a potentially high-resolution record in shallow sediments of the early installation of monsoonal circulation patterns in east Asia. We confirm partly the paleogeography during the early stages of collision in Taiwan: the Chinese margin displayed a pronounced non-cylindrical geometry with a large basement promontory to the west in place of the modern Taiwan mountain range. Collision in Taiwan may have happened at once along the whole length of the modern mountain range, instead of progressively from north to south as classically considered. (C) 2010 Elsevier Ltd. All rights reserved.

Gravity Variation in Siberia: GRACE Observation and Possible Causes

Tue, 27 Mar 2012 09:36:53 GMT

title: Gravity Variation in Siberia: GRACE Observation and Possible Causes abstract: We report the finding, from the GRACE observation, of an increasing trend in the gravity anomaly in Siberia at the rate of up to 0.5 mu gal yr(-1) during 2003/1 - 2009/12, in the backdrop of a negative anomaly of magnitude on the order of similar to-10 mgal. In consideration of the non-uniqueness of the gravitational inverse problem, we examine in some detail the various possible geophysical causes to explain the increasing gravity signal. We find two geophysical mechanisms being the most plausible, namely the melting of permafrost and the GIA post-glacial rebound. We conclude that these two mechanisms cannot be ruled out as causes for the regional gravity increase in Siberia, based on gravity data and in want of ancillary geophysical data in the region. More definitive identification of the contributions of the various causes awaits further studies.