Crustal Velocities from Marine Common Depth Point Reflection Data

2013 ◽  
pp. 271-288
Author(s):  
Joel S. Watkins ◽  
Richard T. Buffler ◽  
Mark H. Houston ◽  
John W. Ladd ◽  
Thomas H. Shipley ◽  
...  
Keyword(s):  
Reflection Data ◽  
Common Depth Point ◽  
Point Reflection

A comparison of legacy and recently acquired multichannel seismic data on 95 Ma Pacific oceanic crust south of the Hawaiian Islands

2020 ◽  
Author(s):  
Phil Cilli ◽  
Tony Watts ◽  
Brian Boston ◽  
Donna Shillington
Keyword(s):  
Oceanic Crust ◽  
Hawaiian Islands ◽  
Separation Distance ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Common Depth Point ◽  
The Pacific ◽  
Original Field ◽  
Multichannel Seismic Reflection Data ◽  
Multichannel Seismic Data

<p>The oceanic crust in the vicinity of the Hawaiian Islands is of tectonic interest because it formed at a fast spreading mid-oceanic ridge during the Late Cretaceous (Turonian) and has been deformed since the Late Miocene by volcanic loads generated at a deep mantle hotspot. We have used legacy and recently acquired multichannel seismic reflection data to determine the character of oceanic crust and the Moho in a region south of the Hawaiian Islands where the Pacific plate has been flexed upwards partly by volcano loading and partly by the dynamics of the hotspot. The legacy data is based on Common Depth Point (CDP) and Constant Offset Profile (COP) data acquired onboard R/V <em>Robert D. Conrad</em> and R/V <em>Kana Keoki</em> during August/September 1982. <em>Conrad</em> was equipped with a 3.6 km long streamer and a 1864 cu. in. airgun array and <em>Kana Keoki</em> was equipped with a 1864 cu. in. array. During the COP experiment the two ships steamed on a similar heading and a separation distance of 3.6 km, yielding an effective offset for reflection data of 7.2 km. Original field data have been re-processed with ‘state-of-the-art’ seismic processing work flows using Shearwater REVEAL software. The recently acquired data was acquired during October 2018 with R/V <em>Marcus G. Langseth</em>, equipped with a 15 km long streamer and a 6600 cu. in. airgun array. Comparisons between the legacy and recently acquired reflection data have been informative, revealing new methods to process <em>Conrad’s</em> legacy of multichannel data acquired on 31 cruises during 1975 to 1989 and new insights on the structure and nature of the Moho in 95 Ma oceanic crust.</p>

To: “High‐resolution common‐depth‐point reflection profiling: Field acquisition parameter design,” by R. W. Knapp and D. W. Steeples, which appeared in February 1986, GEOPHYSICS, p. 283–294

Geophysics ◽  
1986 ◽  
Vol 51 (7) ◽  
pp. 1519-1519
Keyword(s):  
High Resolution ◽  
Parameter Design ◽  
Maximum Frequency ◽  
Common Depth Point ◽  
Point Reflection

The following errors have been detected. p. 288, left column, 3rd paragraph: Change (Figure 4, Knapp and Steeples, 1986, this issue) to (Figure 3, Knapp and Steeples, 1986, this issue). p. 288, right column, 3rd complete paragraph, 3rd sentence: Change “…when the length of the array is equal to about one‐fourth the apparent surface wavelength…” to “…when the length of the array is equal to about one‐half the apparent surface wavelength…”. Next line, change “ [Formula: see text]” to “[Formula: see text]”. Next line, change “[Formula: see text].” to “[Formula: see text]”. Next line, change “one‐fourth” to “one‐half”. Next 2 equations, change “L ⩽ .25…” to “L ⩽ .5…” and [Formula: see text]…” to “[Formula: see text]…”. p. 289, left column: Change [Formula: see text] to [Formula: see text] Following paragraph, 4th line: Change “.75 m.” to “1.4 m.”; and change “When the maximum frequency value approaches and exceeds 100 Hz (apparent frequency equal to about 70 Hz),…” to “When the maximum frequency value approaches and exceeds 200 Hz (apparent frequency equal to about 140 Hz),…”.

Imaging discontinuities on seismic sections

Geophysics ◽  
1988 ◽  
Vol 53 (3) ◽  
pp. 334-345 ◽  
Author(s):  
Ernest R. Kanasewich ◽  
Suhas M. Phadke
Keyword(s):  
Fault Location ◽  
Synthetic Data ◽  
Velocity Model ◽  
Data Set ◽  
Amplitude Correction ◽  
Reflection Data ◽  
Common Depth Point ◽  
Diffraction Patterns ◽  
A New Technique ◽  
Seismic Sections

In routine seismic processing, normal moveout (NMO) corrections are performed to enhance the reflected signals on common‐depth‐point or common‐midpoint stacked sections. However, when faults are present, reflection interference from the two blocks and the diffractions from their edges hinder fault location determination. Destruction of diffraction patterns by poststack migration further inhibits proper imaging of diffracting centers. This paper presents a new technique which helps in the interpretation of diffracting edges by concentrating the signal amplitudes from discontinuous diffracting points on seismic sections. It involves application to the data of moveout and amplitude corrections appropriate to an assumed diffractor location. The maximum diffraction amplitude occurs at the location of the receiver for which the diffracting discontinuity is beneath the source‐receiver midpoint. Since the amplitudes of these diffracted signals drop very rapidly on either side of the midpoint, an appropriate amplitude correction must be applied. Also, because the diffracted signals are present on all traces, one can use all of them to obtain a stacked trace for one possible diffractor location. Repetition of this procedure for diffractors assumed to be located beneath each surface point results in the common‐fault‐ point (CFP) stacked section, which shows diffractor locations by high amplitudes. The method was tested for synthetic data with and without noise. It proves to be quite effective, but is sensitive to the velocity model used for moveout corrections. Therefore, the velocity model obtained from NMO stacking is generally used for enhancing diffractor locations by stacking. Finally, the technique was applied to a field reflection data set from an area south of Princess well in Alberta.

Deep reflection experiments in northeastern Australia, 1976–1978

Geophysics ◽  
1983 ◽  
Vol 48 (12) ◽  
pp. 1588-1597 ◽  
Author(s):  
S. P. Mathur
Keyword(s):  
Sedimentary Basin ◽  
Mineral Resources ◽  
Crust And Upper Mantle ◽  
Recording Time ◽  
Northern Margin ◽  
Free Zone ◽  
Extra Effort ◽  
Reflection Data ◽  
Common Depth Point ◽  
Crustal Reflection

Between 1976 and 1978 the Australian Bureau of Mineral Resources (BMR) recorded deep crustal reflection data at seven sites in northeastern Australia over continuous profiles up to 15 km long by simply extending the recording time to 16 sec during normal sedimentary basin surveys. The record sections show many events with variable strength, continuity, dip, and spatial distribution. By comparing the sections from the longer and the shorter perpendicular traverses, it is possible to discriminate between primary reflections and diffractions, multiples, and other noise events. Based on their character the reflections can be grouped into zones which are interpreted in terms of the nature and structure of the crust. Most of the reflection sections show, below the sedimentary reflections, a thin (2–3 sec) reflection‐free zone underlain by a thick (9 sec or more) zone of numerous reflection segments which varies in thickness and the distribution of reflection segments. The data thus suggest that the upper crust under the sediments is similar in seismic character throughout northeastern Australia. On the other hand, the deeper crust under the Georgina and Drummond basins is significantly different in seismic signature and thickness from that under the Bowen basin and the northern margin of the Galilee basin. It is concluded that good quality deep reflections can be recorded with little extra effort during sedimentary basin surveys using modern multiple‐fold common‐depth‐point (CDP) techniques, and that the data recorded on long traverses, cross‐spreads, and expanded spreads provide information on the structure and composition of the crust and upper mantle with a resolution greater than has been possible before. Such information is valuable in studying the evolution of mineral and petroleum provinces and the lithosphere in general.

Three‐dimensional seismic monitoring of an enhanced oil recovery process

Geophysics ◽  
1987 ◽  
Vol 52 (9) ◽  
pp. 1175-1187 ◽  
Author(s):  
Robert J. Greaves ◽  
Terrance J. Fulp
Keyword(s):  
Enhanced Oil Recovery ◽  
Oil Recovery ◽  
Seismic Data ◽  
Seismic Reflection ◽  
Three Dimensional ◽  
Recovery Process ◽  
Bright Spot ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Common Depth Point

Seismic reflection data were used to monitor the progress of an in‐situ combustion, enhanced oil recovery process. Three sets of three‐dimensional (3-D) data were collected during a one‐year period in order to map the extent and directions of propagation in time. Acquisition and processing parameters were identical for each survey so that direct one‐to‐one comparison of traces could be made. Seismic attributes were calculated for each common‐depth‐point data set, and in a unique application of seismic reflection data, the preburn attributes were subtracted from the midburn and postburn attributes. The resulting “difference volumes” of 3-D seismic data showed anomalies which were the basis for the interpretation shown in this case study. Profiles and horizon slices from the data sets clearly show the initiation and development of a bright spot in the reflection from the top of the reservoir and a dim spot in the reflection from a limestone below it. Interpretation of these anomalies is supported by information from postburn coring. The bright spot was caused by increased gas saturation along the top‐of‐reservoir boundary. From postburn core data, a map of burn volume distribution was made. In comparison, the bright spot covered a greater area, and it was concluded that combustion and injection gases had propagated ahead of the actual combustion zone. The dim spot anomaly shows good correlation with the burn volume in distribution and direction. Evidence from postburn logs supports the conclusion that the burn substantially decreased seismic velocity and increased seismic attenuation in the reservoir. Net burn thicknesses measured in the cores were used to calibrate the dim‐spot amplitude. With this calibration, the dim‐spot amplitude at each common depth point was inverted to net burn thickness and a map of estimated burn thickness was made from the seismic data.

ESTIMATION AND CORRECTION OF NEAR‐SURFACE TIME ANOMALIES

Geophysics ◽  
1974 ◽  
Vol 39 (4) ◽  
pp. 441-463 ◽  
Author(s):  
M. Turhan Taner ◽  
F. Koehler ◽  
K. A. Alhilali
Keyword(s):  
Real Data ◽  
Least Square ◽  
Seismic Reflection Data ◽  
Near Surface ◽  
Reflection Data ◽  
Common Depth Point ◽  
Surface Time ◽  
Before And After ◽  
Nmo Correction ◽  
Static Corrections

The problem of computing static corrections for CDP seismic reflection data is discussed. A new approach is presented and it is related to various existing approaches. The approach consists of using crosscorrelation computations to find time shifts which appear to align the traces of each common‐depth‐point. These shifts are expressed in terms of surface corrections, one for each source and receiver position; a residual NMO correction for each common‐depth‐point; and a fixed correction for each common‐depth‐point. These simultaneous equations form an overdetermined set which can be solved for the unknown static and NMO corrections. The least‐square‐error solution to these equations has an important indeterminancy which is discussed. Methods for its resolution are proposed. Application of the technique to real data is illustrated by several examples. Validity of the corrections is demonstrated by velocity analyses before and after correction of the traces.

Low-energy point-reflection EM

1995 ◽  
Vol 53 ◽  
pp. 610-611
Author(s):  
J. C. H. Spence ◽  
X. Zhang ◽  
J. M. Zuo ◽  
U. Weierstall ◽  
E. Munro ◽  
...  
Keyword(s):  
Low Voltage ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Experimental Point ◽  
Crystalline Substrate ◽  
Point Reflection ◽  
Reflection Geometry ◽  
Optical Analog ◽  
Point Projection ◽  
Atomically Flat

The limited penetration of the low-voltage point-projection microscope (PPM) may be avoided by using the reflection geometry to image clean surfaces in ultra-high vacuum. Figure 1 shows the geometry we are using for experimental point-reflection (PRM) imaging. A nanotip field-emitter at about 100 - 1000 volts is placed above a grounded atomically flat crystalline substrate, which acts as a mirror and anode. Since most of the potential is dropped very close to the tip, trajectories are reasonably straight if the sample is in the far-field of the tip. A resolution of 10 nm is sought initially. The specular divergent RHEED beam then defines a virtual source S' below the surface, resulting in an equivalent arrangement to PPM (or defocused CBED). Shadow images of surface asperities are then expected on the distant detector, out of focus by the tip-to-sample distance. These images can be interpreted as in-line electron holograms and so reconstructed (see X. Zhang et al, these proceedings). Optical analog experiments confirm the absence of foreshortening when the detector is parallel to the surface.

UPAYA PENINGKATAN HASIL BELAJAR PASING BAWAH BOLA VOLI DENGAN PENDEKATAN BERMAIN PADA SISWA KELAS X MAN DEMAK

2020 ◽  
Vol 13 (2) ◽  
pp. 41-55
Author(s):  
Indrianto Arif Ramadhana ◽  
Jeff Agung Perdana
Keyword(s):  
Data Analysis ◽  
Learning Outcomes ◽  
Action Observation ◽  
Student Learning Outcomes ◽  
Affective Domain ◽  
Cognitive Domain ◽  
Reflection Data ◽  
Normalized Gain ◽  
Improve Student Learning ◽  
Planning Action

Forearm pass is one of the materials that must be mastered by students of class X Senior High School. In fact, many students do not yet master and know forearm pass techniques. This research is a classroom action research (CAR) with two cycles. Each cycle consists of 4 stages, namely: planning, action, observation and reflection. Data collection was carried out using observations and questionnaires. Data were analyzed using Hake's Normalized Gain formula. From the results of the study it is known that the psychomotor domain of students increased by 0.42 with average criteria from cycle 1 to cycle 2. The affective domain increased by 0.37 with average criteria. The cognitive domain increased by 0.39 with average criteria. Based on the results of the data analysis, it can be concluded that learning forearm pass techniques with games method can improve student learning outcomes.

Sign in / Sign up

Export Citation Format

Share Document