scholarly journals SINGLE CHANNEL SEISMIC APPLICATION FOR GAS CHARGED SEDIMENT RECONNAISSANCE IN GEOHAZARD STUDY OF PORT CONSTRUCTION AT WETLAND AREA

2016 ◽  
Vol 9 (1) ◽  
pp. 20
Author(s):  
Taufan Wiguna ◽  
Omar Moefti ◽  
Rahadian Rahadian ◽  
Muhamad Irfan

<p class="abstrak">Gas charged sediment as a one of parameter for geohazard study in infrastructure especially in swamp area. Instability of sediment layer for exampel subsidence and landslide result in geohazard potention that caused by gas charged sediment. Seismic single channel can be used to identufy gas charged sediment location. Seabed morphology is collected from bathymetry and tidal survey. From seismic profile interpretation shows gas charged sediment indication in Line A and Line B. That indication emerged by presence of acoustic turbid zone and acoustic blanking. Line A and Line B location will be spotlight in next geotechnic port construction study.</p><p> </p>

2021 ◽  
Vol 9 (1) ◽  
pp. 70
Author(s):  
Pareng Rengi ◽  
Ulil Amri ◽  
Tomi Ramadona ◽  
Ediar Usman ◽  
Bustari Bustari

<p>Aruah Islands is located on an international shipping line adjacent to Malaysia. The important aspect in borderline management is the maritime resource potential, one of which is sea minerals. In order to dig the information about marine mineral resources in Aruah Islands, a high-resolution seismic reflection with low frequency was applied, which capable to detect the depth and identify the sedimentary layers clearly and accurately. The depth of water and sediment layers were detected using an echosounder, reason Navi sound type 210 with a tow fish 100 kHz and shallow seismic boomer with a single channel type and wave energy 200 Joules. Gravity core and grab sampler were used to collect the sediment sample. There were three stages on seismic interpretation: sequence analysis, facies analysis, and reflection character identification. Furthermore, sediments containing coarse sand-sized minerals were observed using a microscope. The measurement result of Aruah Islands water depth was ranging from 0-80 m, the deepest part is on the Northern of Batu Mandi island which was 80 m depth. Seismic profiles indicated that the upper layer of tertiary sedimentary as the youngest rocks. Based on sediment thickness, the thickest area was found on the Western (approx. 50 m) and the Northern (approx. 32 m). In line with the island’s Southern part condition, which was plain or shallow sea exposure, the Southeastern island sediment thickness ranged only about 10-18 m. Generally, based on the analyzed sediment sample, quartz was the main mineral found, which was 60-80% of the composition. Other minerals were zircon, tin, hematite, magnetite, limonite, biotite, and dolomite.</p>


2011 ◽  
Vol 217-218 ◽  
pp. 1430-1437
Author(s):  
Shou Jun Li ◽  
Feng You Chu ◽  
Yin Xia Fang ◽  
Zi Yin Wu

Abstract:The study area of this paper is the slope of Shenhu Area in the northern South China Sea. We interpreted both sub-bottom and single-channel seismic profiles to describe the acoustic characteristic of gas hydrate sediment and to discuss the cause of its formation. We distinguished some abnormal physiognomy and geologic objects that are relative to gas hydrate in profiles. Protuberance, shallow fault, acoustic blank patch, partial enhanced reflection and acoustic blank zone were discovered in the legible sub-bottom profile. The shallow gassy belt locates under the seabed from 34 to 82 m. Contrasting the sub-bottom profile with the data of Chinese first gas hydrate expedition, we believed that the gas in the shallow gassy belt came from the decompounding of gas hydrate in deep stratum. Pockmark, seepage, fold and Bottom Simulating Reflector (BSR) were recognized in the single-channel seismic profile. The depth of BSR is slightly deeper than that of the samples of Chinese first gas hydrate expedition in the study area. We think the BSR in the seismic profile may be the bottom of gas hydrate. Based on the time-depth conversion, we plotted out Oligocene, early Miocene, middle Miocene and Pliocene in the seismic profile according to the sedimentary thickness, sedimentary rate and age of ODP site 1148 and set up the chronology of the gas hydrate sediment.


Geophysics ◽  
2012 ◽  
Vol 77 (5) ◽  
pp. R217-R225 ◽  
Author(s):  
Luiz Alberto Santos ◽  
Webe Joao Mansur ◽  
George A. McMechan

Diffractions carry the same kinematic information provided by common focus point operators (CFPOs). Thus CFPO and diffraction time trajectories may be used separately, or combined into a single unified tomography for velocity analysis. Velocity estimation by tomography of CFPOs reduces the depth-velocity ambiguity compared to two-way time tomography. CFPO estimation is complicated where there are event discontinuities and diffractions. This problem is overcome by using the kinematic information in diffractions in near-offset common-offset gathers. The procedure is illustrated using synthetic data, and a single-channel field seismic profile from the Blake Ridge (off the east coast of the United States). The results show the effectiveness of the proposed method for estimation of velocity from single channel seismic data, and for refinement of the velocity field from multichannel data. Both applications are cost-competitive.


Author(s):  
P. Trebbia ◽  
P. Ballongue ◽  
C. Colliex

An effective use of electron energy loss spectroscopy for chemical characterization of selected areas in the electron microscope can only be achieved with the development of quantitative measurements capabilities.The experimental assembly, which is sketched in Fig.l, has therefore been carried out. It comprises four main elements.The analytical transmission electron microscope is a conventional microscope fitted with a Castaing and Henry dispersive unit (magnetic prism and electrostatic mirror). Recent modifications include the improvement of the vacuum in the specimen chamber (below 10-6 torr) and the adaptation of a new electrostatic mirror.The detection system, similar to the one described by Hermann et al (1), is located in a separate chamber below the fluorescent screen which visualizes the energy loss spectrum. Variable apertures select the electrons, which have lost an energy AE within an energy window smaller than 1 eV, in front of a surface barrier solid state detector RTC BPY 52 100 S.Q. The saw tooth signal delivered by a charge sensitive preamplifier (decay time of 5.10-5 S) is amplified, shaped into a gaussian profile through an active filter and counted by a single channel analyser.


1968 ◽  
Vol 11 (1) ◽  
pp. 189-193 ◽  
Author(s):  
Lois Joan Sanders

A tongue pressure unit for measurement of lingual strength and patterns of tongue pressure is described. It consists of a force displacement transducer, a single channel, direct writing recording system, and a specially designed tongue pressure disk, head stabilizer, and pressure unit holder. Calibration with known weights indicated an essentially linear and consistent response. An evaluation of subject reliability in which 17 young adults were tested on two occasions revealed no significant difference in maximum pressure exerted during the two test trials. Suggestions for clinical and research use of the instrumentation are noted.


2008 ◽  
Vol 1 (2) ◽  
pp. 139-155 ◽  
Author(s):  
YAEL DARR

This article describes a crucial and fundamental stage in the transformation of Hebrew children's literature, during the late 1930s and 1940s, from a single channel of expression to a multi-layered polyphony of models and voices. It claims that for the first time in the history of Hebrew children's literature there took place a doctrinal confrontation between two groups of taste-makers. The article outlines the pedagogical and ideological designs of traditionalist Zionist educators, and suggests how these were challenged by a group of prominent writers of adult poetry, members of the Modernist movement. These writers, it is argued, advocated autonomous literary creation, and insisted on a high level of literary quality. Their intervention not only dramatically changed the repertoire of Hebrew children's literature, but also the rules of literary discourse. The article suggests that, through the Modernists’ polemical efforts, Hebrew children's literature was able to free itself from its position as an apparatus controlled by the political-educational system and to become a dynamic and multi-layered field.


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