Aplikasi Metode Seismik Refraksi dalam Menentukan Lapisan dan Tingkat Kekerasan Batuan di Bawah Permukaan Desa Medana Lombok Utara

The seismic refraction method is one of the geophysical methods which is based on measuring the response of seismic waves in the soil that are fractured along the soil and rock layers. One of the seismic refraction method application is to determine the layers and rocks types below the surface. This study uses a geophone as a catcher for seismic waves that are emitted below the surface. The waves caught on the geophone are converted into seismic data which can be read in a seismograph. Seismic data read by seismographs are already in digital form and stored in the central unit PASI 16S24-P. The results of the data analysis concluded that below the land surface of the village of Medana, there were 3 rock layers with a thickness of the first layer 3-4 meters, the second layer 2-5 meters and the third layer 10-17 meters. The first and second layers are still in the form of soil (less compact), while the third layer is in the form of rock (compact). The level of hardness (density) will be more compact in linear to the depth, the more the depth will be the more compact the rock. The depth in the form of hard rock starts from 16 meters to 23 meters from the ground level of the village of Medana, Central Lombok.

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A comparative study for structural bedrock delineation by using conventional geophysical methods

Bulletin of the Geological Society of Greece ◽

10.12681/bgsg.17217 ◽

2001 ◽

Vol 34 (4) ◽

pp. 1301

Author(s):

Τ. Δ. ΠΑΠΑΔΟΠΟΥΛΟΣ ◽

I. A. ΑΛΕΞΟΠΟΥΛΟΣ ◽

Π. Ι. ΚΑΜΠΟΥΡΗΣ

Keyword(s):

Seismic Refraction ◽

Geophysical Methods ◽

Clear Distinction ◽

The Past ◽

Tectonic Processes ◽

Refraction Method ◽

Limestone Bedrock ◽

Modern Analysis ◽

Seismic Refraction Method ◽

Effective Design

In this paper is examined the potential and effectiveness of two conventional geophysical methods in geotechnical research. The seismic refraction method that has been successfully used in the past for subsurface bedrock delineation in foundation projects, failed to indicate clear distinction between flysch and limestone bedrock material in the area under investigation. This failure is due to the macro-anisotropy structure of the limestone that resulted from joints, tectonic processes or/and karstic phenomena and later fillings of the voids with argillaceous material. The geoelectrical method of vertical sounding, on the other hand, although provided a clear distinction for the bedrock characterization, failed to distinguish the overburden cover from the underlain flysch formation. Finally, in this paper it is shown that for a successful application of geophysical work in geotechnical research, it is required effective design, utilization of modern analysis methods and handling more than geophysical methods.

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SEISMIC REFRACTION METHOD IN THE DETERMINATION OF SITE CHARACTERISTICS

Iraqi Geological Journal ◽

10.46717/igj.53.2d.4ms-2020-10-26 ◽

2020 ◽

Vol 53 (2D) ◽

pp. 53-63

Author(s):

Mundher Alsamarraie

Keyword(s):

Seismic Velocity ◽

Seismic Refraction ◽

Geophysical Methods ◽

Shallow Subsurface ◽

Site Characteristics ◽

Refraction Method ◽

First Arrival ◽

Seismic Refraction Method ◽

Profile Characteristics

Preliminary site properties need geophysical methods to determine it, the same as the large use of the seismic refraction method to detect the layers of soil and the depth reaching the bedrock. This study was conducted to find out the subsurface profile characteristics of a backyard field in UTM, Skudai following the principles of this method. The analysis of seismic data processed using ZondST2D software by determining the first arrival time until we get a block model of 2D shape based on the primary propagation of seismic velocity wave’s in soil layers. It was found that the investigated subsurface profile consists of four layers showing the level of weathering grade ranges from 600–4000 m/s based on the classification of rock mass in Malaysia. It was found that weathering rates decreased at higher depth, with the increase of density for the material and dampness reduction of seismic velocity. It was concluded that the survey of seismic refraction in development can be used only for shallow subsurface profiles and far from noise and disturbance.

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OUTLINING OF SHALE MASSES BY GEOPHYSICAL METHODS

Geophysics ◽

10.1190/1.1439805 ◽

1966 ◽

Vol 31 (4) ◽

pp. 711-725 ◽

Cited By ~ 29

Author(s):

A. W. Musgrave ◽

W. G. Hicks

Keyword(s):

Cross Sections ◽

Seismic Refraction ◽

Geophysical Methods ◽

High Porosity ◽

Reflection Method ◽

Overburden Pressure ◽

Refraction Method ◽

Seismic Reflection Method ◽

High Fluid ◽

Seismic Refraction Method

Shale masses are here defined as large bodies of shale at least several hundred feet in thickness. These may be formed either as diapiric masses or as depositional masses. The shale masses are like salt masses and the two are many times combined to form domal masses; they both may form the updip seal for stratigraphic accumulation of oil. The shale masses exhibit the following properties by comparison to the normal section: (1) low velocities—in the range of 6,500 to 8,500 ft/sec with very little increase of velocity with depth, (2) low densities—estimated to be in the range [Formula: see text] to [Formula: see text], (3) low resistivities—approximately 0.5 ohm‐m, and (4) high fluid pressures—about 0.9 overburden pressure. These properties all seem to be caused by the high porosity and low permeability of these large shale masses. Maps and cross sections of an example area block 113, Ship Shoal Area are shown. The low shale velocities were measured by acoustic logs and verified by refraction shooting. The low densities were deduced from gravity maps. The low resistivities are shown on electric logs, and high pressure is evidenced by the drilling difficulties with heaving shales. These physical properties allow the outlining of the shale mass by one or more of the following ways: the gravity method is used to outline the low density material, the seismic reflection method is used to outline the lack of reflection contrast and in some cases map the velocity configuration, the seismic refraction method is used to indicate the velocity of the anomalous mass, thereby differentiating between shale and salt.

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Applications of Geophysical Methods in Tunnel and Oil Exploration

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/889/1/012015 ◽

2021 ◽

Vol 889 (1) ◽

pp. 012015

Author(s):

Shivam Sharma ◽

Shalini Thakur ◽

Tarun Sharma

Keyword(s):

Seismic Refraction ◽

Geophysical Methods ◽

Oil Sand ◽

Resistivity Method ◽

Refraction Method ◽

Gravity And Magnetic ◽

Different Types ◽

Electrical Resistivity Method ◽

Seismic Refraction Method

Abstract Geophysical studies can be utilized adequately to decide the land, hydro geographical and geotechnical properties of the ground mass in which the designing development is occurring. The investigation must be given to the contractor to ensure the information related to soil or to predict the type of equipment to be used and to estimate productivity and cost. This article examined how integrated geophysical methods were carried out for the determination of the degree of fracturing and rigidity of rock mass. Data were collected from different case studies in which comparison is there between different types of methods suited for different type of evaluations. In this paper, methods involved for the explorations are seismic refraction method, electrical resistivity method, magnetic and gravity method for oil explorations. The authors found that gravity and magnetic are best suited methods for the oil sand exploration and because of the high acceptance of designing a lot latest applications expected in future. The techniques used in these methods are relatively cheap and fast finding in comparison to other methods.

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