2-D velocity structure in Kerala-Konkan basin using traveltime inversion of seismic data     

Praveen Kumar Singh  Kalachand Sain 《Journal of the Geological Society of India》2012,79(1):53-60

The existence of gas-hydrates in marine sediments increases the seismic velocity, whereas even a small amount of underlying free-gas reduces the velocity considerably. The change in velocities against the background (without gas-hydrates and free-gas) velocity can be used for identification and assessment of gas-hydrates. Traveltime inversion of identifiable reflections from large offset multi channel seismic (MCS) experiment is an effective method to derive the 2-D velocity structure in an area. We apply this method along a seismic line in the Kerala-Konkan (KK) offshore basin for delineating the gas-hydrates and free-gas bearing sediments across a bottom simulating reflector (BSR). The result reveals a four layer 2-D shallow velocity model with the topmost sedimentary layer having velocity of 1,680–1,740 m/s and thickness of 140–190 m. The velocity of the second layer of uniform thickness (110 m) varies from 1,890 to 1,950 m/s. The third layer, exhibiting higher velocity of 2,100–2,180 m/s, is interpreted as the gas-hydrates bearing sediment, the thickness of which is estimated as 100 to 150 m. The underlying sedimentary layer shows a reduction in seismic velocity between 1,620 to 1,720 m/s. This low-velocity layer with 160–200 m thickness may be due to the presence of free-gas below the gas-hydrates layer.  相似文献   

Seismicity of Gujarat   总被引：2，自引：2，他引：0  

B. K. Rastogi  Santosh Kumar  Sandeep Kumar Aggrawal 《Natural Hazards》2013,65(2):1027-1044

Paper describes tectonics, earthquake monitoring, past and present seismicity, catalogue of earthquakes and estimated return periods of large earthquakes in Gujarat state, western India. The Gujarat region has three failed Mesozoic rifts of Kachchh, Cambay, and Narmada, with several active faults. Kachchh district of Gujarat is the only region outside Himalaya-Andaman belt that has high seismic hazard of magnitude 8 corresponding to zone V in the seismic zoning map of India. The other parts of Gujarat have seismic hazard of magnitude 6 or less. Kachchh region is considered seismically one of the most active intraplate regions of the World. It is known to have low seismicity but high hazard in view of occurrence of fewer smaller earthquakes of M????6 in a region having three devastating earthquakes that occurred during 1819 (M _w7.8), 1956 (M _w6.0) and 2001 (M _w7.7). The second in order of seismic status is Narmada rift zone that experienced a severely damaging 1970 Bharuch earthquake of M5.4 at its western end and M????6 earthquakes further east in 1927 (Son earthquake), 1938 (Satpura earthquake) and 1997 (Jabalpur earthquake). The Saurashtra Peninsula south of Kachchh has experienced seismicity of magnitude less than 6.  相似文献   

Effect of Source Energy for SASW Testing on Geological Sites     

Jyant Kumar  P. G. Rakaraddi 《Geotechnical and Geological Engineering》2013,31(1):47-66

A number of Rayleigh wave tests were performed on two geological sites by employing a cylindrical mass of 65 kg dropped from a height ranging from 1 to 4 m. For each test, the mass was dropped freely either (1) directly on ground surface, or (2) on a steel circular base plate kept on the ground. Various combinations of source to first receiver distance (S) and receiver spacing (X) were employed. It has been noted that the value of λ _max increases continuously with an increase in the source energy; where λ _max refers to the maximum wavelength up to which the shear wave velocity profile can be obtained with the usage of the spectral analysis of surface waves tests. The inclusion of the steel base plate below the dropping mass leads to a further increase in the value of λ _max . It is also observed that, for the same height of fall, a ground stratum with relatively greater stiffness tends to provide an increased value of λ _max .  相似文献   

Stress drop and its relation to tectonic and structural elements for the meizoseismal region of great 1905 Kangra earthquake of the NW Himalaya     

Kumar  Naresh  Yadav  Dilip K.  Mondal  S. K.  Roy  P. N. S. 《Natural Hazards》2013,69(3):2021-2038

Natural Hazards - Investigations of micro- and low-magnitude earthquakes in the Kangra-Chamba region of the NW Himalaya were performed to evaluate the relationship between earthquake source,...  相似文献   

Ground-motion predictions in Shillong region, northeast India   总被引：1，自引：0，他引：1  

Sankar Kumar Nath  Kiran Kumar Singh Thingbaijam  Soumya Kanti Maiti  Avinash Nayak 《Journal of Seismology》2012,16(3):475-488

We deliver ground-motion prediction equations for Shillong region, northeast India, based on a database generated by finite-fault stochastic simulations. An examination of the regional seismic source characteristics is carried out beforehand. Micro/minor earthquakes (M _W?<?5.0) nucleating at hypocentral depth <21?km in the region recorded at broadband seismic stations are observed to have Brune stress-drop ranging between 2.8 and 99.9?bars. Likewise, macroseismic intensity data for the 1897 Shillong Earthquake that nucleated at a hypocentral depth of ~35?km places the associated stress-drop at 100?200?bars. The apparent variation of the stress-drop parameter with depth is considered with two source zones namely lower-crust and upper-crust. Equations for the lower-crust predict higher ground-motion levels and exhibit affinity to those developed for stable continental region of Eastern North America. The ground-motion levels predicted by the equations for the upper-crust are relatively lower but are still higher compared with those predicted for tectonically active regions, viz., the Himalayas and Western North America.  相似文献   

Potential of Oil Palm Trunk Sap as a Novel Inexpensive Renewable Carbon Feedstock for Polyhydroxyalkanoate Biosynthesis and as a Bacterial Growth Medium     

Bhadravathi Eswara Lokesh  Zubaidah Aimi Abdul Hamid  Takamitsu Arai  Akihiko Kosugi  Yoshinori Murata  Rokiah Hashim  Othman Sulaiman  Yutaka Mori  Kumar Sudesh 《洁净——土壤、空气、水》2012,40(3):310-317

Utilization of cheap renewable carbon feedstock for polyhydroxyalkanoate (PHA) production not only brings down its production cost but also ensures sustainability. The scope of this study was to evaluate the potential of sap extracted from felled oil palm trunk (OPT) as a novel inexpensive renewable carbon source for PHA production. OPT sap was found to be nutritionally rich and contained various fermentable sugars (5.5% w/v) as its major constituent. Termite gut isolate, Bacillus megaterium MC1 grew profoundly in mineral medium with OPT sap as carbon source and a cell density of 10.9 g/L was attained after 16 h of cultivation in shake flask cultures. A maximum poly‐3‐hydroxybutyrate [P(3HB)] content (% cell dry weight; CDW) of 30 wt% and a P(3HB) concentration of 3.28 g/L was recorded. Additionally, OPT sap extracted from younger tree trunks with prolonged storage had higher sugar content (10.8% w/v) and, when used as a growth medium without the addition of any nutrients, supported bacterial growth comparable to commercially available media.  相似文献   

Effect of Shock Loads on the Process Stability and Behavior of an Anammox Hybrid Reactor          下载免费PDF全文

Swati Tomar  Sunil Kumar Gupta 《洁净——土壤、空气、水》2016,44(9):1131-1139

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Bioinoculants and Vermicompost Improve Ocimum basilicum Yield and Soil Health in a Sustainable Production System          下载免费PDF全文

Sanjeet K. Verma  Umesh Pankaj  Khushboo Khan  Rakshapal Singh  Rajesh Kumar Verma 《洁净——土壤、空气、水》2016,44(6):686-693

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Effect of Corrugation and Reinforcement on the Dispersion of SH-wave Propagation in Corrugated Poroelastic Layer Lying over a Fibre-reinforced Half-space   总被引：1，自引：1，他引：0  

Abhishek Kumar Singh  Amrita Das  Anirban Lakshman  Amares Chattopadhyay 《Acta Geophysica》2016,64(5):1340-1369

The presence of porosity and reinforcement in a medium is an important factor affecting seismic wave propagation and plays vital role in many geophysical prospects. Also, the presence of salt and ore deposits, mountains, basins, mountain roots, etc. is responsible for the existence of corrugated boundary surfaces of constituent layers. Such facts brought motivation for the present paper which deals with the propagation of SH-wave in a heterogeneous fluid-saturated poroelastic layer with corrugated boundaries lying over an initially stressed fibre-reinforced elastic halfspace. Closed form of dispersion relation has been obtained and is found in well agreement to classical Love wave equation for isotropic case. The effect of corrugation, wave number, undulation, position parameter, horizontal compressive/tensile initial stress and heterogeneity on phase velocity has been analysed through numerical computation and graphical illustration. Moreover, comparative study exploring the effect of presence and absence of reinforcement in half-space on dispersion curve is the major highlight of the current study.  相似文献   

Production of P(3HB‐co‐3HHx) with Controlled Compositions by Recombinant Cupriavidus necator Re2058/pCB113 from Renewable Resources          下载免费PDF全文

Paramasivam Murugan  Pragya Chhajer  Akihiko Kosugi  Takamitsu Arai  Christopher J. Brigham  Kumar Sudesh 《洁净——土壤、空气、水》2016,44(9):1234-1241

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