Long-term activity of earthquake-induced landslides: A case study from Qionghai Lake Basin,Southwest of China

Earthquake-triggered landslides are a major geological hazard in the eastern Tibetan Plateau, and have prolonged impact on earth surface processes and fluvial system. To determine how long co-seismic landslides affect basins, a massive number of landslides existing in Qionghai Lake Basin were investigated for landslide distribution characteristics and geomorphological evidences, with further comparison and analysis using historic seismic analog method. The landslides found in Qionghai Lake Basin showed clear features of seismic triggering with strongly controlled by Zemuhe fault. These landslides are still active at present. Some new slides generally occur in ancient slope failure zones causing serious secondary hazards in recent years. In this study we strengthen the idea that the landslides triggered by the 185o Xichang earthquake （Ms7.5） have long term activity and prolonged impact on the mountain disasters with a period of more than 16o years. Our results support growing evidence that coseismic landslides have a prolonged effect on secondary disasters in a basin, and invite more careful consideration of the relationship between current basin condition and landslide history for a longer period.     

Measuring temperature variability of five major cities of Pakistan

Changes in surface air temperature during the last century are widely discussed among researches in the field of climate change. This paper measures the variability of annual surface air temperature of five major cities of Pakistan (Lahore, Peshawar, Quetta, Hyderabad and Karachi) for the period from 1882 to 2003. We perform an exploratory analysis which shows that the annual landmass air temperature series of five relatively more important climate stations of Pakistan obey the normal distribution. A subsequent trend analysis shows that the temperature has been increasing in the twentieth century for the five (major) cities of Pakistan, the increase being 0.3°C to 1.0°C. We computations based on Bayesian analysis for two samples (e.g., for Lahore, we use data for the period from 1882 to 1960 and 1961–2000 for first sample and second sample, respectively) of temperature data of five cites shows that the average of annual mean temperature for the second period is higher than the average of first period. Thus, Bayesian inferencing shows that the general pattern of evolution of temperature over Pakistan is pretty similar to the current global warming configuration.     

Influence of Azores High pressure on Middle Eastern rainfall

Several studies demonstrate that North Atlantic Oscillation influences variability of climate over Middle East. We use the centers of action approach for the study of winter rainfall variability over Middle East, taking into account variations in the components of the North Atlantic Oscillation, the Azores High and the Icelandic Low pressure systems. The results show there is a negative relation between the interannual variations of winter rainfall over Middle East and Azores High pressure. The east–west shifts of Indian Ocean high pressure has also impact on precipitation over Middle East, there being more precipitation when the Indian Ocean High shifts eastward versus when it is westward. We present a regression model for Middle East precipitation in which the Azores High pressure and the Indian Ocean High longitude are independent variables and it explains 40 % of the variance of precipitation during 1952–2002. Furthermore, the ongoing decrease in winter precipitation over the Middle East is attributed to the increasing pressure of the Azores High over the same period.     

P-wave minimum 1D velocity model for central and northern Pakistan

Journal of Seismology - We present a P-wave minimum 1D velocity model for central and northern Pakistan along with station delays. The velocity model and appropriate station delays are obtained...     

Potentially harmful metals,and health risk evaluation in groundwater of Mardan,Pakistan: Application of geostatistical approach and geographic information system

This study investigates the values of pH, total dissolved solids (TDS), elevation, oxidative reduction potential (ORP), temperature, and depth, while the concentrations of Br, and potentially harmful metals (PHMs) such as Cr, Ni, Cd, Mn, Cu, Pb, Co, Zn, and Fe in the groundwater samples. Moreover, geographic information system (GIS), XLSTAT, and IBM SPSS Statistics 20 software were used for spatial distribution modeling, principal component analysis (PCA), cluster analysis (CA), and Quantile-Quantile (Q-Q) plotting to determine groundwater pollution sources, similarity index, and normal distribution reference line for the selected parameters. The mean values of pH, TDS, elevation, ORP, temperature, depth, and Br were 7.2, 322 mg/L, 364 m, 188 mV, 29.6 °C, 70 m, 0.20 mg/L, and PHMs like Cr, Ni, Cd, Mn, Cu, Pb, Co, Zn, and Fe were 0.38, 0.26, 0.08, 0.27, 0.36, 0.22, 0.04, 0.43 and 0.86 mg/L, respectively. PHMs including Cr (89%), Cd (43%), Mn (23%), Pb (79%), Co (20%), and Fe (91%) exceeded the guideline values set by the world health organization (WHO). The significant R² values of PCA for selected parameters were also determined (0.62, 0.67, 0.78, 0.73, 0.60, 0.87, ?0.50, 0.69, 0.70, 0.74, ?0.50, 0.70, 0.67, 0.79, 0.59, and ?0.55, respectively). PCA revealed three geochemical processes such as geogenic, anthropogenic, and reducing conditions. The mineral phases of Cd(OH)_2, Fe(OH)_3, FeOOH, Mn₃O_4, Fe₂O_3, MnOOH, Pb(OH)_2, Mn(OH)_2, MnO_2, and Zn(OH)₂ (?3.7, 3.75, 9.7, ?5.8, 8.9, ?3.6, 2.2, ?4.6, ?7.7, ?0.9, and 0.003, respectively) showed super-saturation and under-saturation conditions. Health risk assessment (HRA) values for PHMs were also calculated and the values of hazard quotient (HQ), and hazard indices (HI) for the entire study area were increased in the following order: Cd>Ni>Cu>Pb>Mn>Zn>Cr. Relatively higher HQ and HI values of Ni, Cd, Pb, and Cu were greater than one showing unsuitability of groundwater for domestic, agriculture, and drinking purposes. The long-term ingestion of groundwater could also cause severe health concerns such as kidney, brain dysfunction, liver, stomach problems, and even cancer.     

Analysis of a progressive slope failure in the Xiangjiaba reservoir area,Southwest China

The rehabilitation construction in the reservoir area of Xiangjiaba hydropower station in Southwest China has caused many landslides. A shallow progressive failure that occurred on the resettlement site of Xin’an Town of Pingshan County in Sichuan Province was selected as a case study. This landslide occurred in a long and gently inclined area by slope excavation under rainfall conditions. It is about 3.0 m deep with a total length of 35 m and is composed of some subfailures. Undisturbed samples were retrieved, on which the basic properties, shear strength, expansive potential, mineral compositions, and microstructures were tested and analyzed. The results show (1) the landsliding materials belong to medium expansive soil, consisting of the clay minerals of illite–smectite (I/S) and chlorite–smectite (C/S); (2) shear strength of the soil is sensitive to water, which greatly decreases once saturated; and (3) many fractures and relatively large pores are developed in the soils. Back analysis of the landslide shows that the shear strength at failure is less than the residual shear strength obtained from lab tests, indicating that some processes contributing to the slope failure could not be reflected by the shear box test. Based on the above analysis, the progressive process of the slope failure was interpreted, and it is inferred that the rainfall entered into the slope mainly through fractures and relatively large pores in the soil. It caused not only the great decrease in soil strength but also the swelling trend. The latter one would lead to growth, interaction, and coalescence of the fractures. Soon after, these fractures formed the shear planes (zones), which further decreased the resistance of the landslide. Under these favorable conditions, the slope excavation directly triggered the failure.     

Spatial Distribution of Shear Wave Velocity for Late Quaternary Alluvial Soil of Kanpur City,Northern India

Empirical correlation between standard penetration resistance (SPT-N) and shear wave velocity measured by seismic downhole techniques are prepared of the alluvial soil of quaternary age for the Kanpur city. The Kanpur city is having seismic threat from Himalaya and it falls in seismic zone III according to seismic zones of India. Standard penetration test as well seismic downhole test has been carried out up to 30 m at twelve different locations of Kanpur city. The measured SPT-N values and shear wave velocity values are used to develop empirical correlation between SPT-N and shear wave velocity. The proposed correlations have been compared with the existing regression equations by various other investigators. It is found that the proposed correlation exhibit good performance (10 % error bar). Also the measured shear wave velocity has been used to prepare spatially distributed contour map of 50, 75 and 100 m/s using ArcGIS-9 software. It is observed that the shear wave velocity values for the northern part of Kanpur city vary from 125 to 825 m/s. In southern part, it is varying from 125 to 500 m/s where as in the central part of the city the shear wave velocity varies from 125 to 375 m/s. The eastern part of the city also shows some variation in shear wave velocity which ranges from 250 to 625 m/s. The western part of the city shows the variation of shear wave velocity from ≤125 to 500 m/s. The soil type of the study area are classified as per NEHRP and new Italian O.P.M.C classification system as B, C and D type soil with having site period of 0.1–0.9 s and Poisson’s ratio varying from 0.1 to 0.4.     

Influence of Icelandic Low pressure on winter precipitation variability over northern part of Indo-Pak Region

Several studies demonstrate that North Atlantic Oscillation (NAO) has dominant influence on the variability of climate over Southwest Asia. We deconstruct the NAO into its two components, the Azores High and the Icelandic Low. Regional circulations are influenced by changes not only in the pressure but also the positions of the Azores High and the Icelandic Low. The results presented in this paper exhibit that significantly great portions of interannual variance of winter precipitation over Indo-Pak Region (consists of Northeast Pakistan and Northwest India) can be explained by including the contributions of the Icelandic Low pressure in addition to ENSO and AO. This contribution also explains the physical mechanisms to establish the relationships between the COA and regional climate by examining composite maps of large-scale circulation fields using NCEP/NCAR reanalysis data.     

A probabilistic approach for estimating return period of extreme annual rainfall in different cities of Punjab

Multi-day rainfall events are an important cause of recent severe flooding in Pakistan, and any change in the magnitude of such events may have severe impact upon urban structures such as dams, urban drainage systems, and flood. This article uses statistical distributions to define extremes of annual rainfall of different cities of Punjab (Lahore, Murree, Sialkot, and Jhelum) with given return periods. Our calculations suggest that general extreme value is the best-fitted distribution for the extreme annual rainfall of different cities of Punjab. Our calculations show that different cities of Punjab have 5 years return period for receiving more than 100 mm daily rainfall. While they have 30 years return period for receiving more than 200 mm daily rainfall. This asks for construction of new dams in Pakistan.     

Multi-temporal annual soil loss risk mapping employing Revised Universal Soil Loss Equation (RUSLE) model in Nun Nadi Watershed, Uttrakhand (India)

The present comparative study is multi-temporal in nature. The Revised Universal Soil Loss Equation (RUSLE), remote sensing, and GIS were used to model the soil loss estimation for soil conservation and vegetation rehabilitation in Nun Nadi watershed for the years 2000 and 2009. The estimated mean soil loss for the year 2000 and 2009 is 3,283.11 and 1,419.39 Mg?ha^?1 year^?1, respectively. The study finds that about 80 % area has low or least risk of erosion and about 7 % is exposed to high or very high risk which indicates the improvement in terms of soil loss if we compare the data of both the time periods. The findings show that the rainfall, LULC change, and elevation are the main responsible factors for the soil loss in Nun Nadi watershed. Conservation measures have been adopted; however, the problem still remains serious and demands urgent attention.