Interpretation Of High-resolution Satellite Images Research Articles

Landslides triggered by the 22 July 2013 Minxian–Zhangxian, China, Mw 5.9 earthquake: Inventory compiling and spatial distribution analysis

On July 22, 2013, an earthquake of Ms. 6.6 occurred at the junction area of Minxian and Zhangxian counties, Gansu Province, China. This earthquake triggered many landslides of various types, dominated by small-scale soil falls, slides, and topples on loess scarps. There were also a few deep-seated landslides, large-scale soil avalanches, and fissure-developing slopes. In this paper, an inventory of landslides triggered by this event is prepared based on field investigations and visual interpretation of high-resolution satellite images. The spatial distribution of the landslides is then analyzed. The inventory indicates that at least 2330 landslides were triggered by the earthquake. A correlation statistics of the landslides with topographic, geologic, and earthquake factors is performed based on the GIS platform. The results show that the largest number of landslides and the highest landslide density are at 2400m–2600m of absolute elevation, and 200m–300m of relative elevation, respectively. The landslide density does not always increase with slope gradient as previously suggested. The slopes most prone to landslides are in S, SW, W, and NW directions. Concave slopes register higher landslide density and larger number of landslides than convex slopes. The largest number of landslides occurs on topographic position with middle slopes, whereas the highest landslide density corresponds to valleys and lower slopes. The underlying bedrocks consisting of conglomerate and sandstone of Lower Paleogene (Eb) register both the largest number and area of landslides and the highest landslide number and area density values. Correlations of landslide number and landslide density with perpendicular- and along-strike distance from the epicenter show an obvious spatial intensifying character of the co-seismic landslides. The spatial pattern of the co-seismic landslides is strongly controlled by a branch of the Lintan-Dangchang fault, which indicates the effect of seismogenic fault on co-seismic landslides. In addition, the area affected by landslides related to the earthquake is compared to the relationship of “area affected by landslides vs. earthquake magnitude” constructed based on earthquakes worldwide, and it is shown that the area affected by landslides triggered by the Minxian–Zhangxian earthquake is larger than that of almost all other events with similar magnitudes.

Mapping of Food Agricultural Land Sustainability (LP2B) in Purworejo District

Title : Mapping of Food Agricultural Land Sustainability (LP2B) in Purworejo District. Implementation of Act 41 of 2009 on sustainable agricultural land still needs to be improved. Purworejo has a total area of 103,481.75 hectares consisting of rice, dry land and mixed garden. Increased development of a high enough lead Purworejo prone land conversion primarily agricultural to non-agricultural land. Determination of sustainable agricultural land is expected to control the pace of the transfer function. This study aims to determine the parameters for mapping LP2B and LCP2B, determine the basis for assessing inter-parameter calculation and LCP2B LP2B, determine the characteristics of the grouping criteria as LP2B agricultural land and agricultural land mapping LCP2B and sustainable food (LP2B) Purworejo. The data used in this study include spatial data and spatial data tabulated data consists of the Present landuse map the results of high-resolution satellite image interpretation purworejo district scale 1:25,000, topographic maps, maps of land suitability, administration district map boundaries, and maps of raw paddy fields. Tabulation of data consists of the need and availability of food, food balance, wetland conversion, the rate of population growth, and land area requirements. The survey results revealed that the total population, wetland production, planted area, harvested area, conversion rate and balance of food can be used as a parameter to specify the grouping criteria LP2B while land based on the irrigation system and the productivity of more than 5.5 tonnes / ha with IP is more than 1.75. Based on the analysis Purworedjo county has a total area of 38,562 ha area of agri-food consisting of 27,850.18 ha of wetlands and 10,712 ha of dry land. Of the area that became wet LP2B area of 25,826 ha and 5,243 ha of dry LP2B. Sustainable food agriculture land reserve wet (wet LCP2B) 2,024 ha and sustainable agri-food reserves dry (dry LCP2B) 5,469 ha.

Mapping of Food Agricultural Land Sustainability (LP2B) in Purworejo District

Title : Mapping of Food Agricultural Land Sustainability (LP2B) in Purworejo District. Implementation of Act 41 of 2009 on sustainable agricultural land still needs to be improved. Purworejo has a total area of 103,481.75 hectares consisting of rice, dry land and mixed garden. Increased development of a high enough lead Purworejo prone land conversion primarily agricultural to non-agricultural land. Determination of sustainable agricultural land is expected to control the pace of the transfer function. This study aims to determine the parameters for mapping LP2B and LCP2B, determine the basis for assessing inter-parameter calculation and LCP2B LP2B, determine the characteristics of the grouping criteria as LP2B agricultural land and agricultural land mapping LCP2B and sustainable food (LP2B) Purworejo. The data used in this study include spatial data and spatial data tabulated data consists of the Present landuse map the results of high-resolution satellite image interpretation purworejo district scale 1:25,000, topographic maps, maps of land suitability, administration district map boundaries, and maps of raw paddy fields. Tabulation of data consists of the need and availability of food, food balance, wetland conversion, the rate of population growth, and land area requirements. The survey results revealed that the total population, wetland production, planted area, harvested area, conversion rate and balance of food can be used as a parameter to specify the grouping criteria LP2B while land based on the irrigation system and the productivity of more than 5.5 tonnes / ha with IP is more than 1.75. Based on the analysis Purworedjo county has a total area of 38,562 ha area of agri-food consisting of 27,850.18 ha of wetlands and 10,712 ha of dry land. Of the area that became wet LP2B area of 25,826 ha and 5,243 ha of dry LP2B. Sustainable food agriculture land reserve wet (wet LCP2B) 2,024 ha and sustainable agri-food reserves dry (dry LCP2B) 5,469 ha.

Revisions of the M 8.0 Wenchuan earthquake seismic intensity map based on co-seismic landslide abundance

Hundreds of thousands of landslides were triggered by the May 12, 2008, Mw 7.9 Wenchuan earthquake in China. A detailed inventory of landslides triggered by the earthquake was prepared based on geographic information systems and remote sensing technology. Visual interpretation of high-resolution satellite images and aerial photos taken pre- and post-earthquake and selected field investigation showed that at least 197,481 co-seismic landslides related to the earthquake were triggered throughout an area of approximately 110,000 km2. These co-seismic landslides are delineated as individual solid polygons. The landslides cover a total area of approximately 1,160 km2. Most of the landslides are distributed in an approximate ellipse area with a total area of approximately 44,031 km2. In this paper, quantitative co-seismic landslide criteria for seismic intensity zonation were constructed based on the original “M 8.0 Wenchuan Earthquake Seismic Intensity Map” (MWESIM) and co-seismic landslide abundance analyses. These quantitative criteria, which correspond to landslide area percentages (LAP), indicate the percentage of the area affected by landslides in certain calculation windows and are listed as follows: Areas of LAP ≥70 % correspond to the XII intensity district; areas of 20 % ≤ LAP < 70 % correspond to the XI intensity district; areas of 1 % ≤ LAP < 5 % correspond to the IX intensity district; and areas of LAP <1 % correspond to the VIII and less-than-VIII intensity districts. The VII and greater-than-VII intensity districts of the original MWESIM, which constituted an area of approximately 123,832 km2, were corrected based on the above quantitative criteria. The degrees of fit of the original and revised MWESIMs with the co-seismic landslides were 93.8 and 95.8 %, respectively, indicating a 2.0 % improvement. The quantitative criteria of the constructed earthquake-triggered landslides for seismic intensity zonation can provide a scientific reference, standard, and basis for seismic intensity zonation in other earthquake events, especially those occurring in mountainous areas.

GIS-based bivariate statistical modelling for earthquake-triggered landslides susceptibility mapping related to the 2008 Wenchuan earthquake, China

The main purpose of this research is to evaluate the modelling capability and predictive power of a bivariate statistical method for earthquake-triggered landslide susceptibility mapping. A weight index ( W i ) model was developed for the 2008 Wenchuan earthquake region in Sichuan Province, China, using a wide range of optical remote sensing data, and carried out on the basis of a geographic information system (GIS) platform. The 2008 Wenchuan earthquake triggered 196007 landslides, with a total area of 1150.43 km 2 , in an approximately oblong area around the Yingxiu–Beichuan coseismic surface fault-rupture (the Yingxiu–Beichuan fault). The landslides of the study area were mapped using visual interpretation of high-resolution satellite images and aerial photographs, both pre- and post-earthquake, and checked in the field at various locations. As a consequence, a nearly complete inventory of landslides triggered by the Wenchuan earthquake was constructed. Topographic and geological data and earthquake-related information were collected, processed and constructed into a spatial database using GIS and image processing technologies. A total of 10 controlling parameters associated with the earthquake-triggered landslides were selected, including elevation, slope angle, slope aspect, slope curvature, slope position, lithology, seismic intensity, peak ground acceleration (PGA), distance from the Yingxiu–Beichuan fault, and distance along this fault. To assist with the development of the model, the complete dataset of 196007 landslides was randomly partitioned into two subsets; a training dataset, which contains 70% of the data (137204 landslides, with a total area of 809.96 km 2 ), and a testing dataset accounting for 30% of the data (58803 landslides, with a total area of 340.47 km 2 ). A landslide susceptibility index map was generated using the training dataset, the 10 impact factors, and the W i model. In addition, for a conditionally dependent factor analysis, seven other factor-combination cases were also used to construct landslide susceptibility index maps. Finally, these eight landslide susceptibility maps were compared with the training data and testing data to obtain model capability (success rate) and predictive power (predictive rate) information. The validation results show that the success and predictive rates of the W i modelling exceeded 90% for the approaches that include the use of seismic factors. The final landslide susceptibility map can be used to identify and delineate unstable susceptibility-prone areas, and help planners to choose favourable locations for development schemes, such as infrastructure, construction and environmental protection schemes. The generic component of this research would allow application in other regions affected by high-intensity earthquakes and unstable terrain covering very large areas.

Evidence for Holocene activity of the Yilan-Yitong fault, northeastern section of the Tan-Lu fault zone in Northeast China

The Tan-Lu fault zone (TLFZ) is the largest of the major faults in eastern China. Many strong earthquakes have occurred on its section in North China, but no quake greater than M⩾6 has been documented in history at its northeastern section, the Yilan-Yitong fault (YYF) in Northeast China. It is usually considered that this fault has been inactive since late Quaternary and incapable of generating moderate-sized quakes. This conclusion is, however, questioned by our recent work based on high-resolution satellite image interpretation and field investigation. We found a 70-km-long surface scarp near Fangzheng county in Heilongjiang province (HLJP) and a 20-km-long scarp near Shulan county in Jilin province (JLP), and both are associated with the YYF. The trenches across these two scarps reveal a 14C displacement date of 1730±40years BP at Fangzheng and of 4410±30years BP at Shulan. The dextral offsets of the Songhua River and Second Songhua River and nearly horizontal fault striations indicate that the new activity of the YYF has been dominated by dextral strike slipping with a normal component. These new data suggest that, at least for partial sections, the YYF has been active since the Holocene, implying a potential seismic hazard. However, current quake-protection standards in this region are very low due to the previous view that the YYF fault has not been active since the late Quaternary. If an M⩾7 quake takes place on this fault, it will be a devastating event. Therefore, it is necessary to conduct a detailed study on the whole YYF and to reassess its future seismic risk.

Normal- and oblique-slip of the 2008 Yutian earthquake: Evidence for eastward block motion, northern Tibetan Plateau

The 2008 Yutian Mw 7.1 earthquake occurred in a junction area of the Altyn Tagh, Karakax and Kunlun fault systems and becomes a most northerly normal faulting event in the northern Tibetan Plateau. High resolution satellite image interpretation and field investigation indicate that the surface rupture zone produced by the Yutian earthquake is ~31km long along the Yulong Kashgar fault, a NS-trending fault at the western piedmont of a snow-covered mountain at the headwater of the Yulong Kashgar River, about 20km south of the Ashikule volcanoes. The surface rupture zone along the Yulong Kashgar fault consists of four different types of surface ruptures with both normal- and oblique-slip components. The maximum left-lateral slip and vertical offset, we measured in the field, are ~3.6m and ~3.3m, respectively. This NS-trending seismogenic fault belongs to one of the boundary faults between the Qaidam–Qilian and the western Kunlun blocks. Thus, the Yutian earthquake is as a result of abrupt normal- and oblique-slip faulting, which fits the eastward escape of the Qaidam–Qilian block, relative to the western Kunlun block. This surface rupture pattern supports the eastward block-like motion model whose deformation takes place mainly along the block boundaries delineated by mega-strike-slip faults in the northern Tibetan Plateau. More important may be that the Yutian earthquake has implication on future earthquake risk along the boundary faults of the Qaidam–Qilian block.

Building Damage Estimation by Integration of Seismic Intensity Information and Satellite L-band SAR Imagery

For a quick and stable estimation of earthquake damaged buildings worldwide, using Phased Array type L-band Synthetic Aperture Radar (PALSAR) loaded on the Advanced Land Observing Satellite (ALOS) satellite, a model combining the usage of satellite synthetic aperture radar (SAR) imagery and Japan Meteorological Agency (JMA)-scale seismic intensity is proposed. In order to expand the existing C-band SAR based damage estimation model into L-band SAR, this paper rebuilds a likelihood function for severe damage ratio, on the basis of dataset from Japanese Earth Resource Satellite-1 (JERS-1)/SAR (L-band SAR) images observed during the 1995 Kobe earthquake and its detailed ground truth data. The model which integrates the fragility functions of building damage in terms of seismic intensity and the proposed likelihood function is then applied to PALSAR images taken over the areas affected by the 2007 earthquake in Pisco, Peru. The accuracy of the proposed damage estimation model is examined by comparing the results of the analyses with field investigations and/or interpretation of high-resolution satellite images.

Palaeo-ice streams in the Foxe/Baffin sector of the Laurentide Ice Sheet

In this paper, we describe mapping of palaeo-ice streams in the Foxe/Baffin sector of the Laurentide Ice Sheet by means of geomorphological interpretation of high-resolution satellite images. Our interpretations were guided by a glaciological inversion scheme, aided by digital elevation models, publicly available sonar surveys and field studies. As a result, we produced a map depicting the location, geometry and relative temporal changes of palaeo-ice streams and analysed their palaeoglaciological implications for the Foxe/Baffin sector. We conclude that in the period between the Last Glacial Maximum and approximately 7.0 kyr BP, the Foxe/Baffin sector was largely drained by topographically controlled outlet glaciers and ice streams, which were organized in a relatively stable pattern. During this time, large areas of Melville Peninsula and central Baffin Island were subject to cold-based conditions. Between 7.0 and 6.0 kyr BP, the Foxe/Baffin sector collapsed catastrophically in the Foxe Basin, after which its remnant portion became confined to Baffin Island. During this collapse, rapid successions of small transient ice streams occurred along wide, loosely defined topographical corridors in two sectors of Baffin Island. The presently available landform archive on emerged land is not sufficient to conclusively support the existence of fully scaled ice streams along the whole length of Hudson Strait. As an alternative solution, we propose that topographically controlled ice streams might have occurred along the deepest parts of Hudson Strait, with attendant cold-based ice zones on marginal areas and islands at the head of the strait.