Seismic Research Papers - Academia.edu (original) (raw)

Estimating the shapes, sizes and positioning of subsurface- geological structures are the aims of a geophysical survey. The structural characteristics are important at hydrocarbon exploration because of the relation between this natural... more

Estimating the shapes, sizes and positioning of subsurface- geological structures are the aims of a geophysical survey. The structural characteristics are important at hydrocarbon exploration because of the relation between this natural source with these structures and specifically anticlines. Seismic prospecting is remarkably better than other geophysical methods such as Gravity surveying, geo-electrical surveying, magnetic surveying and radiometric surveying due to various items like good accuracy and resolution or high penetration. The main usage of seismic survey is at hydrocarbon prospecting, but it is utilized in groundwater exploration and civil projects like determining bed rocks at great projects. It seems fossil fuel will have been the significant energy consumption at the end of 21 century, although, there is a lot of studies in order to provide other alternative economical energy sources.

During December 2003, three seismic stations were installed close to the hornitos of the hydrothermal system at Dallol, complemented by radiometer and infrasonic measurements. A combined geophysical data set was collected for about three... more

During December 2003, three seismic stations were installed close to the hornitos of the hydrothermal system at Dallol, complemented by radiometer and infrasonic measurements. A combined geophysical data set was collected for about three days. During this period thermal, seismic and acoustic records indicate the presence of two regimes characterized by a different energy distribution in frequency. Few volcano-tectonic events appear superimposed to the continuous hydrothermal tremor. The continuous data indicate variable shallow processes most likely related with variations in temperature and degassing processes within the shallow geothermal system. This alternation of low and high regimes shows significant similarities with other volcanic systems of different nature, although at Dallol the transition is more evident in the thermal than in the seismic and acoustic data.

This paper is intended to measure the attenuation effects of seismic reflection data derived from spectral decomposition based on Continuous Wavelet Transform (CWT) algorithm. This is a continuation from previous publication which was... more

This paper is intended to measure the attenuation effects of seismic reflection data derived from spectral decomposition based on Continuous Wavelet Transform (CWT) algorithm. This is a continuation from previous publication which was emphasized to carbonate reservoir. In this paper the method is applied in deltaic reservoir which is much thinner and below seismic resolution in most areas. In robust development drilling of channel reservoirs, the AVO method used to identify hydrocarbon zones has been successful with more than 80% success ratio. Ambiguity arose when the magnitude of far stack sections have approximately the same bright anomaly in gas and water reservoirs. It triggered the failure of few wells. The bright anomalies were suspected caused by effects of thin coals or carbonate streaks lying above water wet sand. This caused tuning thickness effect and misinterpreted the response. The frequency gradient methodology was expected to resolve this issue and has proven able to differentiate the response caused by gas and water zones. We performed spectral ratio computations to analyze low and high frequency of pre-stack seismic data and came-up with preliminary conclusion that the low frequency of far stack data can differentiate the response of hydrocarbon and non-hydrocarbon zone. Based on the data, we continue the analysis using frequency attenuation of seismic reflections, derived from the slope of frequency gradient. The slope of frequency gradient was then applied to predict the fluid content. It shows that there is different frequency gradient in gas and dry wells of which then enable us to identify the response of the reservoir caused by gas and water zones. The frequency gradient is exploiting attenuation measurements of seismic reflection, which is believed to be closely related to the saturating fluid. Evidences suggest that hydrocarbon zones are associated with abnormally high values of seismic attenuation.

The purpose of this activity is to inform students about earthquakes and their movements and to give students an idea of how a seismograph works. Even though students may not experience an actual earthquake, the hands-on activity of... more

The purpose of this activity is to inform students about earthquakes and their movements and to give students an idea of how a seismograph works. Even though students may not experience an actual earthquake, the hands-on activity of creating a seismograph will give students an opportunity to visually explore concepts related to earthquakes.

Configuration of building is very much important for good seismic performance of the building. The important aspects affecting seismic configuration of a building are overall geometry, structural system and load part. Those parameters are... more

Configuration of building is very much important for good seismic performance of the building. The important aspects affecting seismic configuration of a building are overall geometry, structural system and load part. Those parameters are behaving different way in flat slab structure and conventional slab structure. Research on the design of structure has started not only India but in other developed countries also. The building still damages due to some or other reasons due to earthquake. In spite of all the weakness in the structure either code imperfection or error in analysis and design, the structure configuration system has played a vital role in Calamity. In general normal frame construction utilize column, slab and beam .however it may be possible undertake construction without providing beams, in such a case the frame system would consist a slab and column without beam. In our study it has been planned to analyses a building having flat slab and conventional slab under the effect of various loading conditions. The focus of our project is to compare the behavior of building having flat slab and having conventional slab using software aid.

A probabilistic seismic hazard assessment using an open source MATLAB software has been accomplished for Ermita, Manila. An Earthquake catalogue with earthquake events within latitudes 13° and 16° N, and the longitudes 119° and 123° E,... more

A probabilistic seismic hazard assessment using an open source MATLAB software has been accomplished for Ermita, Manila. An Earthquake catalogue with earthquake events within latitudes 13° and 16° N, and the longitudes 119° and 123° E, and the active seismic sources were considered in this study. Active seismic sources that contributed to the hazard within the study area include 8 shallow crustal seismic source zones, the Manila Trench Plate in the west, the Philippine Fault Zone in the east and the East Luzon Trench in the northeastern part of Luzon. Other seismic sources are the Lubang Fault and the Casiguran Fault. Earthquake events were sorted to their corresponding seismic sources by their depth and location. The attenuation relationships used are Boore, et.al.(1997) for shallow crustal earthquakes, modified Youngs, et.al(1997) or Petersen, et. al. (2004) and Crouse (1991) for earthquakes developed from subduction zones. The peak ground acceleration (PGA) of the study was calculated and presented based on 2%, 5% and 10% probability of exceedance in 50 years (equivalent to 2500, 1000 and 500 years return period). The probability of exceedance of any given PGA was obtained and plotted to generate the hazard curve for the study area.

Underplatingwas originally proposed as the process of magma ponding at the base of the crust andwas inferred from petrologic considerations. This process not only may add high density material to the deep crust, but also may contribute... more

Underplatingwas originally proposed as the process of magma ponding at the base of the crust andwas inferred from petrologic considerations. This process not only may add high density material to the deep crust, but also may contribute low density material to the upper parts of the crust by magma fractionation during cooling
and solidification in the lower crust. Separation of the low density material from the high-density residue may
be a main process of formation of continental crust with its characteristic low average density, also during the
early evolution of the Earth. Despite the assumed importance of underplating processes and associated fractionation, the available geophysical images of underplated material remain relatively sparse and confined to specific tectonic environments. Direct ponding of magma at the Moho is only observed in very few locations, probably because magma usually interacts with the surrounding crustal rocks which leads to smearing of geophysical signals from the underplated material. In terms of processes, there is no direct discriminator between the traditional concept of underplated material and lower crustal magmatic intrusions in the form of batholiths and sill-like features, and in the current review we consider both these phenomena as underplating. In this broad sense, underplating is observed in a variety of tectonic settings, including island arcs,wide extensional continental areas, rift zones, continental margins and palaeo-suture zones in Precambrian crust. Wereview the structural styles of magma underplating as observed by seismic imaging and discuss these first order observations in relation to the Moho.

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will... more

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

A pre-requisite in slope stability analyses is that the internal structure and the mechanical properties of the soil or rock mass of the slope, are known or can be estimated with a reasonable degree of certainty. Geophysical methods to... more

A pre-requisite in slope stability analyses is that the internal structure and the mechanical properties of the soil or rock mass of the slope, are known or can be estimated with a reasonable degree of certainty. Geophysical methods to determine the internal structure of a soil or rock mass may be used for this purpose. Various geophysical methods and their merits for slope stability analyses are discussed. Seismic methods are often the most suitable because the measurements depend on the mechanical properties that are also important in the mechanical calculation of slope stability
analyses. Other geophysical methods, such as electromagnetic, electric resistivity, self-potential, and gravity methods, may be useful to determine the internal structure, but require a correlation of found boundaries with mechanical properties.

Kajian arkeologi di Lembah Mansuli, Lahad Datu, Sabah Ielah menemukan dua tapak Paleolitik, iaitu Gua Samang Buat dan tapak terbuka Mansuli. Isu utama di Gua Samang Buat ialah berapakah kedalaman sedimen di dalamgua ini selepas... more

Kajian arkeologi di Lembah Mansuli, Lahad Datu, Sabah Ielah menemukan
dua tapak Paleolitik, iaitu Gua Samang Buat dan tapak terbuka Mansuli. Isu utama
di Gua Samang Buat ialah berapakah kedalaman sedimen di dalamgua ini selepas
ekskavasi empat meter masih belum menemui lantai gua. Manakala isu utama di
tapak terbuka Mansuli ialah interpretasi paleoalamnya yang dikatakan bersekitaran
tasik kuno. Maka, kaedah geoftzik telah digunakan untuk cuba menjawab isu ini.
Penggunaan kaedah geofizik di Lembah Mansuli telah berjaya membantu
mengenalpasti ketebalan sedimen di Gua Samang Buat dan membantu membina
paleoalam untuk Lembah Mammli. Ketebalan sedimen gua di Gua Samang Buat
yang boleh di' ekskavasi ialah 12 m di Gua 1 dan 5 m di Gua 2. Data ini
mencadangkan secara relatifberkemungkinan kita boleh menemui lapisan berusia
138,000 tahun dahulu di Gua Samang Buat berdq~rkan usia 46,000 untuk
kedalaman 4 m. Kajian gwifizik di Lembah Mansuli pula mendedahkan wujud
tasik kuno dan sa/iran sungai kuno di Lembah Mansuli. Malah daripada survei
tersebut, ianya juga mendedahkan kemungkinan wujud dua teres tasik kuno. Modelanomali graviti dan magnet juga turut menghasilkan hentuk tasik.

Eight wells (Sapphire Deep-1, Sapphire-1, Sapphire-4, Sapphire-Dd, Saphire-Dh, Scarab-2, Saffron-Df and NDOA-1) were interpreted using the composite well logs and seismic sections in order to our understanding of the stratigraphy of the... more

Eight wells (Sapphire Deep-1, Sapphire-1, Sapphire-4, Sapphire-Dd, Saphire-Dh, Scarab-2, Saffron-Df and NDOA-1) were interpreted using the composite well logs and seismic sections in order to our understanding of the stratigraphy of the offshore, Nile Delta, Egypt. Lithostratigraphic studies aided recognition of the following Miocene-Pliocene rock formations (from base to top); Sidi Salim Formation, Rosetta Formation, Abu Madi Formation, Kafr El Sheikh Formation, El Wastani Formation and Mit Ghamr/Bilqas Formation (Sea Bed). Present study, therefore, is to examine in detail the sequence stratigraphy in the NW Nile Delta area and the hydrocarbon occurrences in the study area (Fig.1). For this purpose, a stratigraphic analysis of the recorded formations was carried out in the NW part of the Nile Delta area.

The standards usually reflect with a certain delay the advances of technology in product manufacturing and the growing requisites of the users. In this paper, national, regional and international standards on steel reinforcing bar are... more

The standards usually reflect with a certain delay the advances of technology in product manufacturing and the growing requisites of the users. In this paper, national, regional and international standards on steel reinforcing bar are analyzed. This is a product for which the standards have a low degree of globalization: the penetration of the corresponding ISO standard is low, and national standards are still dominant. The review includes mechanical properties, bending and re-bending, and chemical analysis; other aspects like traceability, fatigue and adherence are briefly addressed. The aim is to verify trends in the quality constraints that may affect the commercialization and application of rebar. Specifically, the requisites related with seismic behavior and the influence of manufacturing processes (natural hardness, online quenching and tempering, micro-alloying). First, the standards to be analyzed are listed, then each of the researched properties are discussed. Previous papers by the authors on related subjects are used as background [1-3].

Knjiga donosi uvid u stradanja građevina i obnovu grada Zagreba i drugih okolnih mjesta nakon potresa 1880. i 2020. godine.

Concrete structures are very vulnerable to seismic hazard. Damages to these structures could be caused by the poor quality of materials used that do not meet the specifications, or due to excessive overloading, lack of planning criteria... more

Concrete structures are very vulnerable to seismic hazard. Damages to these
structures could be caused by the poor quality of materials used that do not meet the
specifications, or due to excessive overloading, lack of planning criteria which do not
conform with the standards, changes in the function of the building, besides due to the
natural disasters such as earthquake. One of the efforts made to improve the
capability of a reinforced concrete structure is to increase the strength and ductility
of the members using Glass Fiber Reinforced Polymer (GFRP) jacketing. The fullwrapped
GFRP jacketing is a method of retrofitting which is frequently implemented
to the concrete columns to improve their strength and ductility. The aim of this study
is to investigate the axial compressive behavior of square columns retrofitted with
GFRP straps with various spacing of the straps. The results of the experimental study
showed that the spacing of the straps affects significantly the strength and strain
ductility of the concrete columns. The closer the spacing of the straps, the higher the
strength and ductility of the columns.