Potassium concentration was determined using NaI T1 gamma ray spectrometry. This relates to the build-up of stress es and their release. Multiplicative factors computed for grains of various thicknesses by Wintle and Aitken15 were used in the present studies.
The concept of locked segments has been developed to assess the seismogenic potential of a region. The Naini Peak was uplifted along the Nainital Figure 3.
Rock strength decreases with increasing depth and temperature. Tables 3 and 4 represent the illite Hbrel values and chlorite peak area ratios for the various samples. School of Geosciences, University of Geosciences, Wollongong University, New South Wales, Australia Results of a study to date neotectonic movements and past seismic events in Himalaya using the thermoluminescence technique are described.
A brief description of these sites along with a general geological framework is given below. The deepest strata in this zone can store the maximum amount of strain energy, and are therefore the focal point of most earthquakes.
So, it is likely that TL signals of smaller grains will be reduced to a greater extent compared to those of larger grains. It is, however, yet to be established if the accumulation of such stresses and their release as neotectonic movements along faults have any definite periodicity.
In the dislocation annihilation model, annihilation of dislocations of opposite sign may produce a high temperature locally, which results in luminescence emission as in thermoluminescence The sample was placed on a transparent lucite plate inside a sample holder below the guiding cylinder. Present experimental data indicates that grains smaller than a certain threshold size have their TL signals completely reset during faulting.
The strength of the upper crustal rocks is also of the same order7. Frictional resistance is thus easily overcome compared to dry rocks and aseismic deformation may be prevalent in such a situation.
This method, termed as the initial-rise method, can be applied to overlapping peaks using the fractional glow technique The results suggest that TL ages attain a constant value within errors below a certain critical grain size RC.
This was done because of possible exposure to sunlight of the outer surface. For ML measurements, the sample was wrapped in thin aluminium foil and fixed on lucite plate with an adhesive tape. Further, there is a case to study the dependence of ML growth and effect of impacts on TL of the samples and these aspects will be pursued in future.
Figure 7 provides IRSL growth curve and shine plateau for a fault gouge.
Experimental techniques The fault gouges were taken from spots approximately 0. Experiments by Hase28 on TL of samples from fault zones suggest that the crushed material had significantly lower luminescence compared to that from the parent rock. More research on this aspect is necessary and may be rewarding. Thus, in order to find the luminescence age of faulting, estimation of paleodose and annual dose is needed.
This implies a higher probability of zeroing. Historical records are also limited to scattered descriptions spanning only the past few centuries. The suggested peak ratios based on estimation of chlorite peaks for a minimum of 4 aliquots and repeated calculation of peak areas are 1. The Sleepy Hollow Fault is antithetic to the Nainital Fault and is defined by vertical scarps and a straight steep slope demarcating Sleepy Hollow We are grateful to Prof.
Such stresses are released periodically and induce earthquakes and neotectonic activity along the faults.