Resistivimeter SYSCAL PRO SWITCH 72

The earth dam of Salhab, built in 1993 and located in northern-west of Syria consists of two separated embankments. The main one extends east-west along a distance of 895m with 14.5m height, while the second embankment towards northwest-southeast over a distance of 510 m and 11 m of height.

Water flow was observed from the piezometric wells (Pz). In the current case study, the Electrical Resistivity Tomography (ERT) and Self Potential methods were used to characterize the possible zones of water leakage through mapping in detail the subsurface structures of the geological formations underneath and behind the dam body. A number of electrical resistivity tomography profiles combined with SP measurements have been carried out (ERT-P) …more

S-wave velocity measurements along levees in New Orleans using passive surface wave methods

Inspection is an important part of mitigating the hazard to those communities living within the shadow of a levee. Recently, researchers from OYO, CSU East Bay, and Louisiana State University used the Atom, a wireless seismic system manufactured by Geometrics, as part of a simple, non-destructive method for levee inspection. The researchers acquired both active and passive seismic data which is used in identifying shallow subsurface conditions that cannot be evaluated using other non-destructive techniques.

Evaluating and monitoring levee conditions is vitally important, as the human and financial costs associated with failed levees can be great. Following Hurricane Katrina, nearly 80 percent of the city of New Orleans flooded and an estimated 1,400 people lost their lives. One of the contributing causes of the failure of the Industrial Canal was due to thick layers of sand in place of the recommended clay. For the 17th Street Canal, a major factor for its failing was the presence of a layer of water-saturated peat, approximately 9 meters below the surface, and between 1.5 to 6.1 meters thick.

In both of these cases, engineers over-estimated the shear strength of these materials, resulting in a low final factor of safety. In this study, the researchers investigated three sites along levees in the New Orleans, Louisiana, USA, area: Industrial Canal, London Avenue Canal, and 17th Street Canal. These sites sustained damage from Hurricane Katrina in 2005 and have since been rebuilt.

Full 3D electrical resistivity tomography (ERT) obtained with the FullWaver system

In 1963, 270 million of m3 of rocks of Mont Toc crashed into the Vajont reservoir in Northern Italy during its initial filling. The landslide caused a tsunami in the lake in which 50 million of m3 of water overtopped the dam in a wave of 250m, leading to the complete destruction of several villages and towns, and estimated between 1,900 and 2,500 deaths.

A 10 years ongoing project led by Professor Roberto Francese by University of Parma and OGS (Italy) aimed to image below the slipping surface of this great landslide in order to prevail any other catastrophic scenario. In 2015, the team used the FullWaver system together with a high power transmitter (VIP, 5 kW, 10A), all developed by IRIS Instruments.

The FullWaver system is able to deliver a full 3D electrical resistivity tomography (ERT) of the entire landslide without any directional bias. The FW system consists on at least one I-FullWaver dedicated for current readings and several independent and autonomous V-FullWaver (receivers) specifically developed for recording full waveform time domain resistivity. For each receiver, three electrodes are settled aiming to record potential variation at two orthogonal dipoles. There is no cable between each FW boxes. Time series were recorded at 10ms sampling rate.

The Dam Safety Group brings together a group of collaborative members, ideally positioned to use proven geophysical technology, services and products for Dam site investigation and monitoring together with seismic monitoring via earthquake early warning and evaluation systems.

The range of Members Geophysical technologies can be rapidly deployed and can provide an effective means to evaluate subsurface information and contribute to continuous monitoring and condition assessment throughout a structure’s life. Reliable and non-invasive it can be cost effectively integrated with other types of ground surveys to build a visual understanding of the overall subsurface of the site.

Facility Managers and Operators may be required to take decisive action to prevent catastrophic incidents in the event of an earthquake. Earthquake monitoring systems can assist decision making by providing predictive data before an earthquake and to evaluate the structural integrity of the dam or levee immediately after an earthquake.

Click to view or download the Dam Safety Group literature.
The Dam Safety Group brings together a group of collaborative members, ideally positioned to use proven geophysical technology, services and products for Dam site investigation and monitoring together with seismic monitoring via earthquake early warning and evaluation systems.

The range of Members Geophysical technologies can be rapidly deployed and can provide an effective means to evaluate subsurface information and contribute to continuous monitoring and condition assessment throughout a structure’s life. Reliable and non-invasive it can be cost effectively integrated with other types of ground surveys to build a visual understanding of the overall subsurface of the site.

Facility Managers and Operators may be required to take decisive action to prevent catastrophic incidents in the event of an earthquake. Earthquake monitoring systems can assist decision making by providing predictive data before an earthquake and to evaluate the structural integrity of the dam or levee immediately after an earthquake.

The Dam Safety Group brings together a group of collaborative members, ideally positioned to use proven geophysical technology, services and products for Dam site investigation and monitoring together with seismic monitoring via earthquake early warning and evaluation systems.

The range of Members Geophysical technologies can be rapidly deployed and can provide an effective means to evaluate subsurface information and contribute to continuous monitoring and condition assessment throughout a structure’s life. Reliable and non-invasive it can be cost effectively integrated with other types of ground surveys to build a visual understanding of the overall subsurface of the site.

Facility Managers and Operators may be required to take decisive action to prevent catastrophic incidents in the event of an earthquake. Earthquake monitoring systems can assist decision making by providing predictive data before an earthquake and to evaluate the structural integrity of the dam or levee immediately after an earthquake.