The events such as land deformation, changes in some of the parameters like, sea level, tilt, strain, and crustal stress, foreshocks, anomalous seismic activity, b-value, and also changes in seismic wave velocity, water table, radon content and gas spouting are known to precede medium to large earthquakes. In the paper, Spurt of Geosignatures Signifying Possible Precursors to a Major Earthquake in Southwestern Indian Peninsula, H N Singh, D Shanker, V N Neelakandan, J Mathai, V P Singh and M Banerjee have observed several clusters of unusual natural incidents throughout the Kerala State during specific periods and tried to analyze the causative factors for these unusual deformations. After a quiescence period of about three months from March to May 2001, the incidents of collapse of several shallow open wells, draining of water, lowering of water level, land subsidence etc., were observed in various parts of the Kerala which continued up to November 2001. The sudden spurt in various unusual geological incidents including seismic events during 2001 spread over a vast area along the southwest coastal tract of India in the absence of any perceptible ground motion clearly indicates the unstable state of crustal blocks in this shield region. The temporal patterns of occurrences of such incidences have been attributed to the outcome of periodic stress release in the region. The authors of the present paper, analyzing the chain of events coupled with the existence of anomalous seismic activity using dilatancy diffusion model, infer that the region is preparing for a major earthquake.

The focal mechanism solutions give an estimate of the focal stress state of an earthquake. In the paper, Estimation of Stress Level in the Focal Region Before and After the December 26, 2004 M9.0 Sumatra Earthquake, Chen Xuezhong, despite the lingering scientific uncertainties that will probably always surround such complex phenomena, has estimated the stress levels of Sumatra earthquake. The study, based on a few highly reliable teleseismic waveform data, estimates the stress value before this large earthquake to be about 2.79 MPa and after the earthquake to be at 1.51 MPa. The paper concludes that the earthquake occurred under a relatively lower stress level.

Understanding the lateral complexity of carbonate reservoirs and their reservoir quality in both vertical and horizontal distribution is essential to find zones potential for accumulation of hydrocarbons. The paper, Petrophysical Evaluation of the Lower Cretaceous Thamama III, Northern Offshore in Abu Dhabi, UAE, Amir Gabr evaluates the reservoir quality of Thamama III in Zakum oil field, the main reservoir of the northern offshore oil fields of Abu Dhabi, United Arab Emirates. The study, through spatial distribution of the different petrophysical parameters such as pay zone thickness, shale content, porosity, permeability, fluid resistivity, water saturation and hydrocarbon saturation in the zones of hydrocarbons, reveals that the most effective diagenetic events are characterized by intra-matrix dissolution, moldic porosity and fracturing. These diagenetic events are found to follow a pattern locally by precipitation of well-crystalline rhombic dolomite partial cavity and fracture fillings. The porosities and permeabilities, and the best reservoir characteristics are observed towards northeastern direction.

Knowledge of geotechnical conditions of an area is a prerequisite to develop a modern sustainable urban area. When geotechnical status of the area is made available before planning, various environmental problems can be effectively managed and reduced remarkably. In the paper, Geotechnical Condition of Subsurface Fluvial Sediments in Pabna Town and its Adjoining Areas, Bangladesh, Md. Sultan-Ul-Islam, Md. Shamsuzzaman and Md. Badrul Islam present a detailed report on the geotechnical conditions of the Pabna Town area and correlated the subsurface lithology and geotechnical characteristics of soils. A geotechnical map, which distinctly divides the area into four major units has been prepared. The authors recommend that the geotechnical assessment of the subsurface sediments is essential before construction of civil engineering structures in the area because of the presence of plastic organic clay in several places of the Pabna town and adjoining areas.

- GRK Murty
Consulting Editor