GFZ owns and operates a Slim Wave Borehole Geophone Chain (manufacturer Sercel, France). It has a maximum number of 17 levels with 3-component 15 Hz geophones each. The available spacing cable length between levels is 10 m. In principle also other spacings may be confectioned at additional costs. Different clamping arm lengths allow deployments in various hole sizes. For depth correlation the geophone chain can be run combined with a total natural GR and a CCL (casing collar locator). The chain is specified for 135 °C (150 °C peak) and 100 MPa. The geophone chain is available as service only, i.e. operated by experienced GFZ personnel. The seismic chain of the GFZ will be made available for projects on proposal basis. Contact points for planning campaigns are Dr. R. Giese and Jochem Kück.