Gravity Surveys Services - Brochure

LandTech has performed Gravity surveys since 1998. The LandTech team has developed techniques that combine the latest Gravity meters and computing technology, to provide accurate and cost-effective surveys. Our survey operations span the globe, having successfully undertaken major contracts in many countries. Thousands of gravi-ty stations have been surveyed. LandTech’s reputation for precision field work is a direct result of the overriding commitment to survey quality by our dedicated staff of internationally experienced sur-veyors, engineers and gravity technicians. LandTech has developed GRAPAS® a joint Passive Seismic Tomography (PST) Data and Bouguer gravity residuals inver-sion. It consists of the reiteration of a set of n iterations of the seismological inversion, leading to a new velocity model and new event locations, followed by one inversion of the gravity data and the computation of a new density contrast model. This procedure is repeated until the convergent criteri-on is satisfied. Using this method, it is possible to estimate what information is brought to the model by seismic and gravity data. The flow chart illustrates the organization of thi sequential method. LandTech’s Passive Seismic Tomography inversion program calculates the 3-D V p model and new earthquake locations from the arrival times of local earthquakes. This process is stopped after n iterations. This 3-D absolute V p model is then converted into a 3-D relative density contrast model using Birch’s law. At this stage, the linear inverse gravity problem is solved leading to a new density contrast model that is transformed back to a new V p model. This completes the first loop of the sequential inversion. The following loops use the same procedure defining as input the final velocity model of the previous loop. The sequential process is stopped when the standard deviations between observed data and theoretical values calculated from the models stop decreasing significantly between two loops. LandTech’s engineers have recently developed GRAMAPAS® a joint inversion program of PST, gravity and magnetotellurics data. Joint Inversion Seismic &Gravity &MT Data Landtech Enterprises SA Head Office ,32 Kifisias Ave. ATRINA B, Marousi 151 25, Athens, GREECE. Tel: +302106826450, Fax:+302106826455, Email: info@landtechsa.com www.landtechsa.com