Equipment for vertical displacements
A promising research perspective for vertical displacements is the measurement of the sea bottom pressure using absolute pressure gauges (APG) during transient deformation events (e.g. see the results of Wallace et al [2016], from the Hikurangi subduction zone).
The principle is simple: APGs deployed on the seafloor continuously record changes in pressure by the overlying water column. Vertical seafloor rise (e.g. decreasing depth) in response to tectonic deformation will be recorded as a pressure decrease (decreasing water depth). Vertical downward movement will induce a pressure increase (increasing water depth). To detect vertical deformations on the order of cm’s, the MARMOR project will acquire:
- Four (at least) non-drifting Absolute Pressure Gauges of the latest generation equipped with A-0-A devices allowing drifts of less than 1mm/year for long duration (> 3 years) , monitoring experiments (e.g. APG developed by Paroscientific);
- Five (at least) Abosolute Pressure Gauges for rapid intervention and short duration (of less than a few months), monitoring experiments
- Acoustic sonar systems to separate the absolute pressure variations due the changes of the properties of the water column from those due to the real (tectonic) vertical movements.
