The time frequency analysis of seismic data gives rise to many features that were hitherto difficult to visualize by the analysis of time amplitude data. The changes of seismic timing events may result from thickness variations or a strong lateral change in interval velocity. In the paper, "Seismic Sequence Analysis by Frequency Transition: A Case Study from the Himalayan-Tibet Areas", the authors, Syed Mustafizur Rahman, M Rezaul Islam, Mumnunul Keramat and Md. Sultan-Ul-Islam have proposed a seismic reflection sequence analysis that can be used to study the presence of thin strata by sequence stratifying the seismic data. The application of seismic attributes has been introduced for the seismic sequence analysis, which has been used for stratification of the subsurface in the Himalayan-Tibet areas. Reflecting interfaces of the thin layers are also distinctly observed in the enlarged portions and the analysis provides the thickness of various layers including thin beds.

The Analytic hierarchy process (AHP) is known to be a systematic procedure for representing the elements of a multicriteria decision-maker problem hierarchically. A decision-making problem is cut into numerous smaller parts by means of AHP, and then decision makers lead through a series of pairwise comparison judgments to express the relative intensity of the impact of the elements in the hierarchy. Geographic Information System (GIS) in conjunction with remote sensing, geophysical data, as well as other governmental records can be used to determine the preliminary hazard/suitability of a given site. In the paper, "Preliminary Hazard Assessment by Integrating Geophysical and Other Data Sources, NW Gulf of Suez, Egypt: A GIS Multicriteria Approach", the authors, A M Youssef and E Tarabees have highlighted a new approach using a GIS in integration with the AHP to accomplish a site hazard/suitability assessment for both surface and subsurface factors. The authors have investigated the hazard/suitability of the area, around port Ain Sokhna, east of Cairo city, Egypt, for locating different geotechnical projects in the area by integrating GIS with AHP. Multiple cartographic and geophysical themes representing the geologic, geomorphic, physiographic and geotechnical characteristics of the surface and subsurface layers of the study area—that affect the site hazard/suitability for any civil projects—were created from existing data, maps and remotely sensed images, as well as from field studies. This assessment has delineated areas with characteristics that indicate surface and subsurface problems. The study could be vital in identifying the areas most suitable for urban expansion and, thereby, in minimizing the risks and costs associated with the construction on these areas.

Water being the most vital requirement for the mankind and available surface water resources being inadequate to meet the requirement for different purposes, the search for subsurface water has been on the increase. Application of geophysical methods is very effective in the delineation of aquifer zones and their depth, water content estimation and water quality assessment. In the paper, "Estimation of Aquifer Thickness from Vertical Electrical Sounding Data (Schlumberger Method) in the Area Near Malanpur, Bhind (MP)", the authors, Vineesha Singh and M C Khare have acquired Vertical Electrical Sounding (VES) data using Schlumberger method together with borehole lithologs that were available in the region in and around Malanpur area of Bhind district, Madhya Pradesh to delineate different aquifers, depth of the rock and their thickness. The study reveals that groundwater occurs mostly in the unconsolidated sediments comprising of layers having different proportions of clay mixed with kankar, sand and silt. In sandstone, groundwater occurs in weathered and fractured zones.

In the paper, "GIS Point Scoring for Good Water Bearing Zone Identification at Sweta River, Kallar Basin, Tamil Nadu, India", the authors, Gurugnanam B, Prabaharan N, Vasudevan S, Sulochanasekhar and Lingeswara Rao S V have demarcated potential zones of water bearing zones by applying geophysical method and GIS technique using Arc GIS software. The isoresistivity contour maps of the region are prepared by contouring the apparent resistivity values which are helpful in delineating low apparent resistivity zones.

The extent of damage due to an earthquake depends on several factors such as the magnitude, the hypocenter, epicenter distance, terrain, the type of population, structural design of the buildings, weather conditions, and the time of occurrence. In the paper, "Application of Rule-Based Mamdani Type Fuzzy Modeling to Quantitative Damage Analysis of Indian Earthquakes", the authors, S Vijayachitra and A Tamilarasi have developed rule-based Mamdani Type Fuzzy Inference System (MTFIS) in order to analyze the assessment of damage of 100 earthquakes observed in India, and have applied the same successfully for the quantitative damage analysis of earthquakes. The authors have made a comparative analysis between MTFIS modeling and statistical analysis by using regression method.

Remote sensing satellite data proved to be a useful tool in the delineation of geomorphic features and lineaments. Preservation of neotectonic activities which produce landscape changes, such as river course modifications, abrupt swings in river courses, development of paleo/buried, abandoned channels and lakes, could be identified through satellite images. In the paper, "Remote Sensing for Deriving Neotectonic Evidences from Disorganized River Course and Riverine Geomorphology of Mendha River Area, Rajasthan", the authors, V S Rathore and M S Nathawat have processed the satellite images of the Mendha river catchment area, in Rajasthan. They have discussed the geomorphology, drainages and lineaments using visual interpretation as well as digital image processing techniques of IRS-1D LISS III image of 2002 and Landsat image of 1975 of the Mendha river catchment area, in Rajasthan. The study revealed the presence of two sets of lineaments trending in NE-SW and NNW-SSE direction that appear to control the Mendha river course. They have concluded that the geomorphic features, such as abandoned, paleo/buried channel and saline playas of the area, are of recent origin.

- S V Srirama Rao
Consulting Editor