b'Geophysics in the surveysNewsGeological Survey of South Australia: Gravity database updatedOver the last couple of years themodule had used AHD heights - andcombinations to calculation the Bouguer geophysicists at the Geological Surveythe new module retains this - but it alsoAnomalies.of South Australia have been planningcalculates the Bouguer Anomaly as per and implementing a series of changesthe spherical cap equations using GDA94This is now viewable in SARIG (Figure 1). to the existing gravity module on oneellipsoidal heights. The Bouguer AnomalyWhen a user undertakes a spatial search of their primary geoscientific databases:fields have been labelled as BAslab andon the Gravity Stations layer, the pop-SA Geodata. Data from SA GeodataBAscap to differentiate the two. Theup table includes the usual columns of feed directly into the South Australiandatabase also calculates the Free Airdata, plus a selection of the new fields. Resources Information Gateway (SARIG),Anomaly. Specifically, the new ellipsoidal heights, an online platform where users canthe Spherical Cap Bouguer Anomaly, the access and download a variety ofAs well as these new anomalies, theGrid Flag and the Free Air Anomaly. The geoscientific information. updated module has some othernext upload to Jetstream is scheduled for features. Weve included a field titledlate November 2021 and will include an The gravity module on SA Geodata (angrid_flag. This is simply a yes or no fieldupdated gravity station layer, making it Oracle database) is the South Australianand indicates whether individual stationseasy to cookie-cut select portions of the single point of truth for gravity datahave been used in the latest state grid.gravity layer.and metadata. The database calculatesIn cases where surveys of (say) differentThe geophysicists are now continuing the Bouguer Anomaly from uploadedvintages are overlapping it often becometheir ongoing project of uploading more data: position and height information,necessary to filter out some points tosurveys onto the database. During the observed gravity and point number, asensure a coherent image. We do notdatabase development we paused this well and information pertaining to allundertake further levelling of individualwork but now the database is up and the datums used. The Bouguer Anomalygravity surveys on SA Geodata; therunning we can recommence this work.calculated is a simple Bouguer Anomaly,dataon the database are as we received assuming a slab model of the Earth. them. As always, for assistance with SARIG and accessing geophysical data, please The updated module still requires thisThe new module is also GDA2020contact Customer Services resources.basic information, but also requiresfriendly. Coordinates of any datumcustomerservices@sa.gov.au.the user to upload additional heightand projection can be uploaded onto information: ellipsoidal heights in thethe database, and the database willPhilip Heath GDA94 and GDA2020 datums. Thecalculate and store GDA94 and GDA2020Geological Survey of South Australia Bouguer Anomaly calculated in the oldcoordinates. It will then use the correctPhilip.Heath@sa.gov.auFigure 1.The updated gravity table in SARIG includes new columns of data, including the Spherical Cap Bouguer Gravity.OCTOBER 2021 PREVIEW 24'