Central Geological Survey, MOEA

About: Central Geological Survey, MOEA is a government organization based out in Taipei, Taiwan. It is known for research contribution in the topics: Landslide & Fault (geology). The organization has 68 authors who have published 81 publications receiving 2037 citations. The organization is also known as: Jīngjì Bù Zhōngyāng Dìzhí Diàochá Suǒ.

Geomorphological evolution of landslides near an active normal fault in northern Taiwan, as revealed by lidar and unmanned aircraft system data

Abstract: . Several remote sensing techniques, namely traditional aerial photographs, an unmanned aircraft system (UAS), and airborne lidar, were used in this study to decipher the morphological features of obscure landslides in volcanic regions and how the observed features may be used for understanding landslide occurrence and potential hazard. A morphological reconstruction method was proposed to assess landslide morphology based on the dome-shaped topography of the volcanic edifice and the nature of its morphological evolution. Two large-scale landslides in the Tatun volcano group in northern Taiwan were targeted to more accurately characterize the landslide morphology through airborne lidar and UAS-derived digital terrain models and images. With the proposed reconstruction method, the depleted volume of the two landslides was estimated to be at least 820 ± 20 × 106 m3. Normal faulting in the region likely played a role in triggering the two landslides, because there are extensive geological and historical records of an active normal fault in this region. The subsequent geomorphological evolution of the two landslides is thus inferred to account for the observed morphological and tectonic features that are indicative of resulting in large and life-threatening landslides, as characterized using the recent remote sensing techniques.

Seismology-based early identification of dam-formation landquake events

Abstract: Flooding resulting from the bursting of dams formed by landquake events such as rock avalanches, landslides and debris flows can lead to serious bank erosion and inundation of populated areas near rivers. Seismic waves can be generated by landquake events which can be described as time-dependent forces (unloading/reloading cycles) acting on the Earth. In this study, we conduct inversions of long-period (LP, period ≥20 s) waveforms for the landquake force histories (LFHs) of ten events, which provide quantitative characterization of the initiation, propagation and termination stages of the slope failures. When the results obtained from LP waveforms are analyzed together with high-frequency (HF, 1–3 Hz) seismic signals, we find a relatively strong late-arriving seismic phase (dubbed Dam-forming phase or D-phase) recorded clearly in the HF waveforms at the closest stations, which potentially marks the time when the collapsed masses sliding into river and perhaps even impacting the topographic barrier on the opposite bank. Consequently, our approach to analyzing the LP and HF waveforms developed in this study has a high potential for identifying five dam-forming landquake events (DFLEs) in near real-time using broadband seismic records, which can provide timely warnings of the impending floods to downstream residents.

Methanoculleus taiwanensis sp. nov., a methanogen isolated from deep marine sediment at the deformation front area near Taiwan

Abstract: A mesophilic, hydrogenotrophic methanogen, strain CYW4T, was isolated from deep-sea sediment obtained by the Ocean Researcher I cruiser, ORI-961, in 2011. The sediment was from the deformation front area offshore of south-western Taiwan. Here, seismic reflections indicated that methane hydrates were abundant. The methanogenic substrates utilized by strain CYW4T were formate and H2/CO2, but not acetate, secondary alcohols, methylamines, methanol and ethanol. Cells of strain CYW4T were non-motile, irregular cocci and 0.6–1.5 µm in diameter. The S-layer protein had an M r of 112 000. The optimum growth conditions were at 37 °C, pH 8.1 and 0.08 M NaCl. Growth of the strain was stimulated by acetate. The G+C content of the chromosomal DNA of strain CYW4T was 61 mol%. Phylogenetic analysis revealed that strain CYW4T was most closely related to Methanoculleus marisnigri JR1T (96.82 % 16S rRNA gene sequence similarity). Based on the morphological, phenotypic and phylogenetic characteristics presented here, it is evident that strain CYW4T represents a novel species of the genus Methanoculleus , and the name Methanoculleus taiwanensis sp. nov. is proposed. The type strain is CYW4T ( = BCRC AR10043T = NBRC 110782T). The optical density of cultures of strain CYW4T dropped abruptly upon entering the stationary growth phase. During this time numerous particles of approximately 50 nm in diameter were observed on and around the cells. This suggests that strain CYW4T harbours a lytic virus that is induced in the stationary phase, which is of interest because only a few lytic viruses have been reported in methanogens.