scholarly journals Spatial and Temporal Distribution of Geologic Hazards in Shaanxi Province

2021 ◽  
Vol 13 (21) ◽  
pp. 4259
Author(s):  
Shizhengxiong Liang ◽  
Dong Chen ◽  
Donghuan Li ◽  
Youcun Qi ◽  
Zhanfeng Zhao
Keyword(s):  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Temporal Distribution ◽  
Shaanxi Province ◽  
Impact Factors ◽  
Dominant Factor ◽  
2008 Wenchuan Earthquake ◽  
The North ◽  
Northern Shaanxi ◽  
Spatio Temporal

The spatio-temporal distribution of geological hazards, including collapses, landslides, and debris flows, in Shaanxi province, China was studied based on data from 1951 to 2018. The potential impact factors, including the geomorphologic types, rivers, roads, rainfall, and earthquakes, were analyzed using Random Forests. The results indicated that most hazards occurred in summer (i.e., July–September) and were triggered by rainstorms. The freeze–thaw effect had a considerable contribution to hazards in the north. Spatially, most hazards in the north occurred in valley terraces of the Loess Plateau, while medium-relief terrane (relief ranged from 500 to 1000 m) in the southern Qinling Mountains were hazard-prone areas. The collapses and landslides were mainly affected by human factors in Northern Shaanxi, whereas in Southern Shaanxi geomorphology was the primary factor. Permeability was a dominant factor for debris flows. In addition, the 2008 Wenchuan earthquake had a remarkable influence on the spatial distribution of hazards. In contrast, for the situation in the Sichuan province, which was close to the earthquake epicenter, the Wenchuan earthquake triggered many collapse and landslide events in the southwest regions of Shaanxi province only on 12 May 2008. The thresholds for the three hazard types in the north and south regions were almost the same despite their distinctly different geologic characteristics. Through a sensitivity analysis, we found an appropriate dry period of 12 h for the area.

Upper-plate structural controls on the segmentation of the Kefalonia Fault (Ionian Sea, Greece)

2021 ◽  
Author(s):  
Emmanuel Skourtsos ◽  
Haralambos Kranis ◽  
Spyridon Mavroulis ◽  
Efthimios Lekkas
Keyword(s):  
Eastern Mediterranean ◽  
Source Parameters ◽  
Plate Boundary ◽  
Temporal Distribution ◽  
Western Coast ◽  
African Plate ◽  
Plate Structure ◽  
The North ◽  
Macroseismic Effects ◽  
Spatio Temporal

<p>The NNE-SSW, right-lateral Kefalonia Transform Fault (KTF) marks the western termination of the subducting Hellenic slab, which is a part of the oceanic remnant of the African plate. The inception of the KTF, described as a STEP fault, is placed in the Pliocene. KTF is considered to be the most active earthquake source in the Eastern Mediterranean. During the last two decades, four significant earthquakes (M>6.0) have been associated with the KTF. These events are attributed to the reactivation of different segments of the KTF, which are (from North to South) the North Lefkada, South Lefkada, Fiskardo, Paliki and Zakynthos segments: the North Lefkada segment ruptured in the 2003 earthquake, the 2014 Kefalonia events are associated with the Paliki segment and the 2015 Lefkada earthquake with the South Lefkada (and possibly the Fiskardo) segments.</p><p>The upper plate structure in the islands of Lefkada and Kefalonia is characterized by the Ionian Unit, thrusted over the Paxi (or Pre-Apulian) Unit. The Ionian Thrust, which brings the Ionian over the Paxi Unit, is a main upper-plate NNW-SSE, NE-dipping structure. It runs through the island of Lefkada, to be mapped onshore again at the western coast of Ithaki and at SE Kefalonia. Two other major thrusts are mapped on this island: the Aenos thrust, which has a WNW-ESE strike at the southern part of the island and gradually curves towards NNW-SSE in the west and the Kalo Fault in the northern part. These Pliocene (and still active) structures developed during the late-most stages of thrusting in the Hellenides, strike obliquely to the KTF and appear to abut against it.</p><p>We suggest that these thrusts control not only the deformation within the upper plate, but also the earthquake segmentation of the KTF. This suggestion is corroborated by the spatio-temporal distribution and source parameters of the recent, well-documented earthquake events and by the macroseismic effects of these earthquakes. The abutment of the Ionian thrust against the KTF marks the southern termination of the Lefkada earthquake segment, which ruptured in the 2003 earthquake, while the Aenos, (or the Kalo) thrust mark the southern end of the Fiskardo segment. The spatial distribution of the Earthquake Environmental Effects related to the four significant events in the last 20 years displays a good correlation with our interpretation: most of the 2003 macroseismic effects are located in the northern part of Lefkada, which belongs to the upper block of the Ionian thrust; similarly, the effects of the 2014 earthquakes of Kefalonia are distributed mainly in the Paliki Peninsula and the southern part of the island that belong to the footwall of the Aenos thrust and the 2015 effects are found in SW Lefkada, which is part of the footwall of the Ionian thrust.</p><p>We suggest that correlation between upper-plate structure and plate boundary faulting can provide insights in the understanding of faulting pattern in convergent settings, therefore contributing to earthquake management plans.</p>

scholarly journals Debris-flow activity in abandoned channels of the Manival torrent reconstructed with LiDAR and tree-ring data

2011 ◽  
Vol 11 (5) ◽  
pp. 1247-1257 ◽  
Author(s):  
J. Lopez Saez ◽  
C. Corona ◽  
M. Stoffel ◽  
A. Gotteland ◽  
F. Berger ◽  
...  
Keyword(s):  
Debris Flow ◽  
Tree Ring ◽  
Debris Flows ◽  
Temporal Distribution ◽  
Alluvial Fan ◽  
Tree Ring Data ◽  
Pine Trees ◽  
Spatio Temporal ◽  
Flow Activity ◽  
Abandoned Channels

Abstract. Hydrogeomorphic processes are a major threat in many parts of the Alps, where they periodically damage infrastructure, disrupt transportation corridors or even cause loss of life. Nonetheless, past torrential activity and the analysis of areas affected during particular events remain often imprecise. It was therefore the purpose of this study to reconstruct spatio-temporal patterns of past debris-flow activity in abandoned channels on the forested cone of the Manival torrent (Massif de la Chartreuse, French Prealps). A Light Detecting and Ranging (LiDAR) generated Digital Elevation Model (DEM) was used to identify five abandoned channels and related depositional forms (lobes, lateral levees) in the proximal alluvial fan of the torrent. A total of 156 Scots pine trees (Pinus sylvestris L.) with clear signs of debris flow events was analyzed and growth disturbances (GD) assessed, such as callus tissue, the onset of compression wood or abrupt growth suppression. In total, 375 GD were identified in the tree-ring samples, pointing to 13 debris-flow events for the period 1931–2008. While debris flows appear to be very common at Manival, they have only rarely propagated outside the main channel over the past 80 years. Furthermore, analysis of the spatial distribution of disturbed trees contributed to the identification of four patterns of debris-flow routing and led to the determination of three preferential breakout locations. Finally, the results of this study demonstrate that the temporal distribution of debris flows did not exhibit significant variations since the beginning of the 20th century.

Analisys of mud inrush water sources into underground working of the Sokolovskoe ore deposit

2020 ◽  
pp. 56-67
Author(s):  
E. Yu. Efremov
Keyword(s):  
Hydraulic Conductivity ◽  
Large Scale ◽  
Underground Mining ◽  
Temporal Distribution ◽  
High Water ◽  
The North ◽  
Initial Block ◽  
Groundwater Supply ◽  
Spatio Temporal ◽  
Inrush Water

There is a serious threat of groundwater inrush from overlying sedimentary layers for underground mining. When ore is extracted using block caving method, the area of overburden collapse over ore zone disrupts the natural structure of high hydraulic-conductivity and low hydraulic-conductivity layers. This process creates conditions for the accumulation and transfer of groundwater to mine workings, which lead to accidents, up to disastrous proportions. The research aim is to determine the spatio-temporal distribution of mud inrushes, and to identify groundwater supply sources of inrushes to reduce the geotechnical risks of underground mining in Sokolovskaya mine. Research methods include localization, classification, and analysis of monitoring data, comparison of mud inrushes distribution with geostatistical parameters of the main aquifers.The majority of large-scale accidents caused by mud inrushes are confined to the central and northern area of caved rock zone. The most risky stage of the ore body extraction is the initial block at the lower extraction level. The sources of water supply for the majority of the mud inrushes are high water level areas of the Cretaceous aquifer to the north and west of the mine. Rational targeted drainage aimed at draining the identified areas of the aquifer is the best way to reduce the risk of accidents.

scholarly journals Research experiment on infiltration and runoff in Jujube land of northern Shaanxi Province

2015 ◽  
Vol 368 ◽  
pp. 174-179
Author(s):  
X. Song ◽  
P. Bai
Keyword(s):  
Relative Error ◽  
Mean Squared Error ◽  
Shaanxi Province ◽  
Richards Equation ◽  
Mean Relative Error ◽  
The North ◽  
Cumulative Infiltration ◽  
Northern Shaanxi ◽  
The Mean ◽  
Research Experiment

Abstract. To provide guidance for the efficient use of rainwater in Jujube forests of the northern Shaanxi Province, research on the processes of infiltration and runoff under field simulated rainfall were conducted. The process of infiltration and runoff-yield on sloping land was simulated with Richards equation and the water balance equation under different rainfall intensities and soil water content, in the north of Shaanxi province. It reached results via comparing with observation results: the mean relative error of the period cumulative infiltration was less than 3%, with a root mean squared error (RSME) less than 0.3. The mean relative error of the period cumulative runoff was less than 12.5%, RSME < 0.4. The simulation results were reasonable; however, the simulation ponding time generally lagged behind measured ponding time probably because of spatial variation of saturated hydraulic conductivity and uneven rainfall.

scholarly journals The 13 August 2010 catastrophic debris flows after the 2008 Wenchuan earthquake, China

2012 ◽  
Vol 12 (1) ◽  
pp. 201-216 ◽  
Author(s):  
Q. Xu ◽  
S. Zhang ◽  
W. L. Li ◽  
Th. W. J. van Asch
Keyword(s):  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Drainage System ◽  
Preventive Measure ◽  
Simultaneous Occurrence ◽  
2008 Wenchuan Earthquake ◽  
The 2008 Wenchuan Earthquake ◽  
Seismic Fault ◽  
Loose Deposits

Abstract. From 12 to 14 August 2010, heavy rainstorms occurred in the Sichuan province in SW China in areas which were affected by the 2008 Wenchuan Earthquake, inducing catastrophic debris flows. This disaster is named as "the 8.13 debris flows". The results of the research presented in this paper show that the 8.13 debris flows are characterized by a simultaneous occurrence, rapid-onsets, destructive impacts, and disaster chain effects. They are located along the seismic fault, because the source materials mainly originate from loose deposits of landslides which were triggered by the Wenchuan Earthquake. The presence of large amounts of these loose materials on the slopes and the development of high intensity rainfall events are the main causes for the formation of these debris flows. The study of the 8.13 debris flows can provide a benchmark for the analysis of the long-term evolution of these debris flows in order to make proper engineering decisions. A flexible drainage system is proposed in this paper as a preventive measure to mitigate the increasing activity of these debris flows in the earthquake-affected area.

scholarly journals Using Google Earth Engine to monitor co-seismic landslide recovery after the 2008 Wenchuan earthquake

2020 ◽  
Author(s):  
Wentao Yang ◽  
Wenwen Qi ◽  
Jian Fang
Keyword(s):  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Google Earth ◽  
Mean Annual Precipitation ◽  
2008 Wenchuan Earthquake ◽  
Computing Platform ◽  
Seismic Landslides ◽  
The 2008 Wenchuan Earthquake ◽  
Vegetation Condition ◽  
Google Earth Engine

Abstract. Earthquake-triggered landslides can pose serious threats to mountain communities by remobilizing and providing loose materials for debris flows in post-seismic years. However, how long co-seismic landslides recover remains elusive due to limited observations. Using vegetation dynamics, we studied surface recovery of co-seismic landslides induced by the 2008 Wenchuan earthquake from May 2008 to July 2019 for over 20,000 km2. Landsat derived vegetation recovery on all co-seismic landslides has been assessed based on the Google Earth Engine, a cloud-based computing platform. We found most co-seismic landslides have been recovering after the earthquake but the spatial pattern is heterogeneous. The epicentre region with low elevations along the bottom of the Min River valley has the best landslide recovery, whereas many landslides on the high Longmen Mountain are poorly recovered ten years after the earthquake. These unrecovered hillslopes and gullies together with widespread loose debris indicate that surface processes on high mountains may still active and may provide source materials for debris flows, threatening communities at low elevations. To decipher possible mechanisms, we further analysed the relations between landslide recovery and twelve influencing factors, including slope, pre-seismic vegetation condition, landslide depth, landslide area, elevation, ground peak acceleration of the earthquake, aspect, slope curvatures, topographic positions, mean annual precipitation, ground cohesion strength and vegetation types. We found elevation, topographic position and pre-seismic vegetation condition are the most important factors that influence landslide recovery over all others. This work also demonstrates the efficiency of the Google Earth Engine for continuously monitoring landslide dynamics over large areas.

scholarly journals Arabian Sea Tropical Cyclones: A Spatio-Temporal Analysis in Support of Natural Hazard Risk Appraisal in Oman

2021 ◽  
Author(s):  
Suad Al-Manji ◽  
Gordon Mitchell ◽  
Amna Al Ruheili
Keyword(s):  
High Risk ◽  
Tropical Cyclones ◽  
Natural Hazard ◽  
Temporal Distribution ◽  
Storm Surges ◽  
Temporal Analysis ◽  
The North ◽  
Risk Areas ◽  
Spatio Temporal ◽  
Extreme Winds

Tropical cyclones [TCs] are a common natural hazard that have significantly impacted Oman. Over the period 1881–2019, 41 TC systems made landfall in Oman, each associated with extreme winds, storm surges and significant flash floods, often resulting in loss of life and substantial damage to infrastructure. TCs affect Omani coastal areas from Muscat in the north to Salalah in the south. However, developing a better understanding of the high-risk regions is needed, and is of particular interest in disaster risk reduction institutions in Oman. This study aims to find and map TC tracks and their spatio-temporal distribution to landfall in Oman to identify the high-risk areas. The analysis uses Kernel Density Estimation [KDE] and Linear Direction Mean [LDM] methods to better identify the spatio-temporal distribution of TC tracks and their landfall in Oman. The study reveals clear seasonal and monthly patterns. This knowledge will help to improve disaster planning for the high-risk areas.

scholarly journals Two multi-temporal datasets that track the enhanced landsliding after the 2008 Wenchuan earthquake

2019 ◽  
Vol 11 (1) ◽  
pp. 35-55 ◽  
Author(s):  
Xuanmei Fan ◽  
Gianvito Scaringi ◽  
Guillem Domènech ◽  
Fan Yang ◽  
Xiaojun Guo ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Debris Flows ◽  
Temporal Evolution ◽  
The Tibetan Plateau ◽  
Mass Wasting ◽  
Epicentral Area ◽  
2008 Wenchuan Earthquake ◽  
Rain Gauges ◽  
Multi Temporal ◽  
Coseismic Landslide

Abstract. We release two datasets that track the enhanced landsliding induced by the 2008 Mw 7.9 Wenchuan earthquake over a portion of the Longmen Mountains, at the eastern margin of the Tibetan Plateau (Sichuan, China). The first dataset is a geo-referenced multi-temporal polygon-based inventory of pre- and coseismic landslides, post-seismic remobilisations of coseismic landslide debris and post-seismic landslides (new failures). It covers 471 km2 in the earthquake's epicentral area, from 2005 to 2018. The second dataset records the debris flows that occurred from 2008 to 2017 in a larger area (∼17 000 km2), together with information on their triggering rainfall as recorded by a network of rain gauges. For some well-monitored events, we provide more detailed data on rainfall, discharge, flow depth and density. The datasets can be used to analyse, on various scales, the patterns of landsliding caused by the earthquake. They can be compared to inventories of landslides triggered by past or new earthquakes or by other triggers to reveal common or distinctive controlling factors. To our knowledge, no other inventories that track the temporal evolution of earthquake-induced mass wasting have been made freely available thus far. Our datasets can be accessed from https://doi.org/10.5281/zenodo.1405489. We also encourage other researchers to share their datasets to facilitate research on post-seismic geological hazards.

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