Designing the configuration of the Geodetic-Geodynamic Network in Israel Gilad Even-Tzur Department of Mapping and Geo-Information Engineering Faculty of Civil and Environmental Engineering TECHNION - Israel Institute of Technology ISGDM-2005, March, Jaén, Spain

The Geodetic-Geodynamic Network (G1) ► Includes 160 points that homogeneously cover the state of Israel (Blue circles and Red squares) ► The location of the points was determined mainly according to geological considerations ► The points were built according to very high technical specifications, to ensure their geotechnical stability

The goal of the Geodetic- Geodynamic Network ► A potential geodetic network for monitoring deformations in primary and secondary known faults ► Serves as the major geodetic control network of Israel

The First Measurement Campaign ► During 1996 the G1 network was measured for the first time ► The network was measured by four GPS receivers ► Sessions of 24 hours ► Most network points were measured in two independent sessions ► The data processing was carried out using the BERNESE

The Network Sensitivity ► Based on the first campaign, a sensitivity analysis was performed in the northern part of the network ► The analysis indicated that the sensitivity of the network was too low ► The analysis also indicated that an identical second measurement campaign will not be sufficient to detect possible movements and deformations A new network design is needed

Network Configuration of the Second Campaign ► The second campaign was held in 2002 ► Only 100 points were measured (Blue circles) ► 5 new points were fixed in the northern part of the network (Yellow circles ) ► 11 continuous permanent GPS stations were operated (Green triangles)

Vector Configuration Design of the Network ► An effective design of the GPS measurements decreases campaign costs and increases the accuracy and reliability of the network ► The goal of the design is to improve the network, so that it would enable the detection and measurements of expected movements and deformations ► A method, based on sensitivity analysis, was used for the GPS vector configuration design ► The method uses a velocity field of the network points, calculated from an assumed geological model

Geological Model ► Locked Fault model in the Dead Sea Rift the fault is locked from the surface down to depth D, and slips freely below this depth by V millimeters per year

Sensitivity Analysis ► Based on statistical test of Hypothesis Accepted if: ► If is true, the test statistic has a non-central F distribution with non-centrality parameter given by :

Sensitivity Analysis ► We define as the boundary value of λ, which will cause the null hypothesis to be rejected at probability levels α and β, the value is an implicit function ► Our aim is designing a monitoring network, which will enable the rejection of the null hypothesis and the acceptance of the alternative hypothesis  Sensitive Network

Sensitivity Analysis ► Since the first GPS campaign has already been carried out in 1996 N 1 has been defined ► We create the normal matrix N 2 which contains the sessions with the most effective contribution to the sensitivity of the network 8 sessions provide a sufficiently sensitive network

Configuration Design of the Network ► To increase the reliability of the network, each point was measured in three independent sessions ► The duration of each session was planned for 8 hours with epoch interval of 30 sec ► The network was designed for measurements using four receivers 92 sessions for 105 points

Broken lines - The eight sessions that provide sufficiently sensitive network The designed sessions of the northern part of the Geodetic-Geodynamic network

The ability of the network to sense horizontal velocity The typical precision of the network points: ► 1996: 3-4 mm for the horizontal component ► 2002: 2-3 mm for the horizontal component We can roughly estimate the ability of the network to sense horizontal velocity along the Dead Sea rift for a velocity of two millimeters per year