Fractal Behaviour of the Earth System

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Fractal behavior of electrical properties in oceanic and continental crust

273-278The fractal behavior of electrical properties of oceanic and upper continental crust was examined for different lithological units encountered in boreholes of Ocean Drilling Program (ODP) and German Continental Deep Drilling Program (KTB), using wavelet transform and Welch averaged periodogram methods. Results obtained from both the sites reveal that the electrical properties in oceanic as well as upper part of continental crust are fractal in nature. The scaling exponent obtained by periodogram analysis has shown variation with lithology and for continental crust it decreases with an increase in depth, which reveals that the electrical crust is more homogeneous at deeper levels than at shallow levels

Evidence of continental crust in Laxmi Basin (Arabian Sea) using wavelet analysis

117-121The spectral analysis of bathymetry along 17°12'N latitude between the longitude ~60°E and 73°E has been done using wavelet transform. The profile covers all the major features of the region including Western Basin, Laxmi Ridge, Laxmi Basin, Panikkar Ridge, continental slope and continental shelf. The wavelet coefficients at different scales a = 1, 2, 4, 8, 16, 32 showed that the signatures are different on the left and right regions of the Laxmi Ridge. On the basis of these signatures, the profile has been divided into different sections and wavelet variance analysis for these sections has been done. The calculated exponent β has the value ~2.0771 for whole data set and ~1.9367, 2.838, 2.9911 and 2.8750 corresponding to Western Basin, Laxmi Basin, region from Laxmi Basin up to continental shelf and region covering continental slope and continental shelf respectively. The fractal dimension corresponding to these values are 1.53, 1.1, 1.0 and 1.06 respectively. The values of β and fractal dimension show that the spectral behaviour of crust of Laxmi Basin is near to continental shelf and slope, which indicates the nature of crust of Laxmi Basin as continental

Interpretation of gravity data over the 85 ºE ridge and Afanasy Nikitin

279-284The 85 ºE ridge is an enigmatic buried aseismic ridge having the peculiar negative gravity anomaly in the north and positive anomaly in the south. Different theories are proposed for the negative anomaly over the 85 ºE ridge. High-resolution two-dimensional satellite gravity data over 85 ºE ridge is interpreted using the spectral analysis method covering the area from 5ºS to 18 ºN. The area consists of the Afanasy Nikitin seamount, partially buried hills and the 85 ºE ridge. Twelve overlapping blocks of 3º3º are selected to calculate the depth of anomalous sources. The two layers of anomalous sources are observed for all blocks. The different depth values of causative sources are found for different portion of the 85 ºE ridge. The deeper depth values for each block are representing the crustal thickness. The maximum thickness of 25.6 km was found for block 10 covering the area between latitude 12 ºN to 15 ºN. The average crustal thickness decreases from north to south along 85º E ridge. The reason of negative free air gravity anomaly below the 85 ºE may be due to the depression in the Moho

Power law distribution of susceptibility and density and its relation to seismic properties: An example from the German Continental Deep Drilling Program (KTB)

We examine the nature of continental crust from the power law scaling behaviour of magnetic susceptibility and density variations. We analyze the data from the main hole of the German Continental Deep Drilling Program (KTB) using the Fast Fourier Transform (FFT) and the multitaper method. On the basis of depth-dependent behaviour of the calculated scaling exponents the KTB well can be divided into four zones of depth 0–0.8 km, 0.8–3.5 km, 3.5–7.7 km and 7.7–9.1 km which are also lithologically distinguishable. The scaling exponents for the susceptibility data correlate by 22–32% and 16–25% with the conversion log and the fracture density. In the case of density a correlation between the scaling exponent values and conversion log and the fracture density are found to be 19–45% and 44–66%, respectively. The multitaper method provides more reliable values of scaling exponents and calculated values are having higher correlation with the conversion log and fracture density than the FFT. The defined zones 3 and 4 are having lower values of scaling exponents and higher values of fractal dimension than the shallower sections. This observation indicates an increase of crustal heterogeneity in terms of fault or fracture density

Would Makran tsunami skip Mumbai, India? No it would reach 8 minutes later than Ratnagiri

620-623Tsunami from Makran subduction zone in the northern Arabian sea are seen to arrive at Ratnagiri (16°56´24.00˝N, 72°40´12.00˝E) along the west coast of India 8 minutes earlier than Mumbai (18°59´24.00˝N,71°52´12.00˝E) in spite Ratnagiri being 244 km down south of Mumbai. This can give rise to a false signal and could be interpreted as tsunami skipped Mumbai and is traveling towards south. However, this advance information at Ratnagiri could be used for quick evacuation of densely populated coastal areas of Mumbai. Reasons for later arrival of tsunami at Mumbai is mainly due to a wide shelf of greater than 250 km whilst at Ratnagiri the shelf suddenly becomes half that of Mumbai. The importance of shelf width along the west coast of India which plays a great role in the arrival of the tsunami waves and the wave heights at different locations are conferred in the present study