Terrain mapping by reflectorless laser rangefinding systems for inner zone gravity terrain corrections

Lyman, Gregory D.; Aiken, Carlos L. V.; Cogbill, Allen H.; Balde, Mamadou; Lide, Chet

doi:10.1190/1.1885939

Cited by 9 publications

(3 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Before the availability of digital terrain data, terrain corrections were calculated graphically by laying a template resembling a dartboard over a topographic map, averaging elevations within segments of annular zones about the gravity station, and using a table to determine the terrain correction (Hammer, 1939). Inner-zone terrain corrections are still done this way, although reflectorless laser, range-finding systems are becoming more popular (Lyman et al, 1997). Bott (1959) and Kane (1960Kane ( , 1962 were the first to use digital terrain data for terrain corrections.…”

Section: Standard Data Reductionmentioning

confidence: 99%

Historical development of the gravity method in exploration

et al. 2005

View full text Add to dashboard Cite

The gravity method was the first geophysical technique to be used in oil and gas exploration. Despite being eclipsed by seismology, it has continued to be an important and sometimes crucial constraint in a number of exploration areas. In oil exploration the gravity method is particularly applicable in salt provinces, overthrust and foothills belts, underexplored basins, and targets of interest that underlie high-velocity zones. The gravity method is used frequently in mining applications to map subsurface geology and to directly calculate ore reserves for some massive sulfide orebodies. There is also a modest increase in the use of gravity techniques in specialized investigations for shallow targets. Gravimeters have undergone continuous improvement during the past 25 years, particularly in their ability to function in a dynamic environment. This and the advent of global positioning systems (GPS) have led to a marked improvement in the quality of marine gravity and have transformed airborne gravity from a regional technique to a prospect-level exploration tool that is particularly applicable in remote areas or transition zones that are otherwise inaccessible. Recently, moving-platform gravity gradiometers have become available and promise to play an important role in future exploration. Data reduction, filtering, and visualization, together with low-cost, powerful personal computers and color graphics, have transformed the interpretation of gravity data. The state of the art is illustrated with three case histories: 3D modeling of gravity data to map aquifers in the Albuquerque Basin, the use of marine gravity gradiometry combined with 3D seismic data to map salt keels in the Gulf of Mexico, and the use of airborne gravity gradiometry in exploration for kimberlites in Canada.

show abstract

Section: Standard Data Reductionmentioning

confidence: 99%

Historical development of the gravity method in exploration

et al. 2005

View full text Add to dashboard Cite

show abstract

“…The standard recommended way to evaluate innermost zone terrain correction (up to approximately 100 m) is to use in-situ geodetic measurements (e.g. LaFehr et al, 1988;Steinhauser et al, 1990;Lyman et al, 1997;Hinze et al, 2005;Schiavone et al, 2009 and others). However, this approach demands additional costs and it is time consuming.…”

Section: Introductionmentioning

confidence: 99%

“…There was a problem to obtain quasi-regularly spaced data using laser range-finder farther than about 30 m around the measurement points, because the obstructed view and inaccessible terrain as well as the frequent occurrence of fog (e.g. Lyman et al, 1997) also pointed to the problem with dense fog). Therefore the use of available digital terrain models (DTM) for terrain correction calculations is still topical, even in the inner zone.…”

Section: Introductionmentioning

confidence: 99%

Inner zone terrain correction calculation using interpolated heights

Zahorec

2015

Contributions to Geophysics and Geodesy

View full text Add to dashboard Cite

The discrepancy between real heights of gravity points and the elevation model has a significant impact on the terrain corrections calculation especially within the inner zone. The concept of interpolated heights of calculation points used instead of measured ones within the specified inner zone can considerably decrease the resulting errors. The choice of appropriate radius of the inner zone for use of interpolated heights is analysed on synthetic topography model as well as real data. The tests with synthetic models showed the appropriate radius of this zone is proportional to the deformation wavelength of the model. Simple statistical analysis of a particular elevation model can give an estimate of the appropriate radius for the calculation using interpolated heights. A concept with interpolated heights in the zone 0–250 m is used in actual practice in Slovakia. The analysis of regional gravity data from the Tatry Mountains test area indicates the searched radius should be about 100 m. Detailed gravity measurements from different areas showed the searched radius does not play so important role but the use of interpolated heights instead of measured ones is still relevant. The more reasonable method instead of using interpolated heights is also presented when calculating the topographic effect.

show abstract