U. S. Department of Interior, U. S. Geological Survey
Open-file report 00-490

Principal Facts for Gravity Data Collected in the Southern Albuquerque 
Basin Area and a regional compilation, Central New Mexico

by Cindy L. Gillespie, V. J. S. Grauch, Kim Oshetski, and G. R. Keller

ABSTRACT
Principal facts for 156 new gravity stations in the southern 
Albuquerque basin are presented.  These data fill a gap in existing 
data coverage.  The compilation of the new data and two existing data 
sets into a regional data set of 5562 stations that cover the 
Albuquerque basin and vicinity is also described.  Bouguer anomaly and 
isostatic residual gravity data for this regional compilation are 
available in the two digital files hueboug.lis and huegrv.asc, 
described briefly below.  These files, the procedures, and the data are 
explained more thoroughly in the file huereport.pdf.  This file can be 
read using Adobe Acrobat reader 4.0.  This software is available free 
of charge at http://www.adobe.com.

DIGITAL FILES
There are two digital data files containing the principal facts for the 
regional compilation of the gravity data, including the 156 new 
stations.  The file "hueboug.lis" lists the facts for the Bouguer 
anomaly in table format for readability.  The file "huegrv.asc" lists 
the facts in sequence for computer program use and includes the 
isostatic residual gravity value as well as the Bouguer anomaly value.  
Note that the values of observed gravity and station elevations are 
represented differently in the two files.  In hueboug.lis, a constant of 
900,000 has been subtracted from the observed gravity value; in 
huegrv.asc the constant subtracted is 980,000.  The difference arises 
from the different requirements of the files:  readability for the first 
file, numerical precision for the second file.  Station elevations are 
listed in feet in hueboug.lis and in meters in huegrv.asc.

The FORTRAN format to read the sequential file huegrv.asc, after 3 lines
of ASCII header information, is (a8,8x,9e16.8), an 8-character id and 9 
channels of data.  The 9 channels of data are longitude in decimal 
degrees, latitude in decimal degrees, station elevation in meters, 
observed gravity in mGals with a constant of 980000 removed, inner 
terrain correction (Hammer zones a-f) in mGals, outer terrain correction 
(Hammer zones g-o) in mGals, free-air gravity in mGals, complete Bouguer 
anomaly (density=2.67 g/cc) in mGals, and isostatic residual gravity in 
mGals.

There are 5562 stations in the file huegrv.asc, which extend somewhat 
beyond the study area in all directions.  During the compilation 
procedure, blanks in the original id's for some stations were 
substituted with 0's.  

DISCLAIMERS
This publication and online data were prepared by an agency of the 
United States Government.  Neither the United States Government nor any 
agency thereof nor any of their employees makes any warranty, expressed 
or implied, or assumes any legal liability or responsibility for the 
accuracy, completeness, or usefulness of any information, apparatus, 
product, or process disclosed in this report or represents that its use 
would not infringe privately owned rights.  Reference therein to any 
specific commercial product, process, or service by trade name, 
trademark, manufacturer, or otherwise does not constitute or imply its 
endorsement, recommendation, or favoring by the United Sates Government 
or any agency thereof. 

Although all online data have been used by the USGS, no warranty, 
expressed or implied, is made by the USGS as to the accuracy of the 
data and related materials and (or) the functioning of the software.  
The act of distribution shall not constitute any such warranty, and no 
responsibility is assumed by the USGS in the use of these data, 
software, or related materials.

The data contacts are

V. J. S. ("Tien") Grauch
U. S. Geological Survey
Box 25046, MS 964
Federal Center
Denver, CO  80225-0046
phone:  303-236-1393
email:  tien@usgs.gov

and

G. Randy Keller
Dept. of Geological Sciences
Pan American Center for Earth and Environmental Studies
University of Texas at El Paso
El Paso, TX  79968-0555
phone:  915-747-5850
email:  keller@geo.utep.edu