Bedrock localization with deep imaging up to 500 ft/152m

After a drilling campaign bedrock depth was not found as probably to deep.

Sue to somme limitation by drilling the only other solution is to make a high-resolution image of the near-surface to localize the bedrock position.

Following several successes defining the subsoil characterization, S-scan solution has been deployed to confirm bedrock localization.

To secure what will be done, a deep imaging results up to 500 ft/152 m depth has been realized.

• Deployments of ultra dense accelerometers array (WiNG)
• Specific processing of low frequencies with S-scan solution

Blue Line 1 : 300 ft/91 m length ,  100 sensors, 3 ft/90 cm spacing

Green line 2 : 100 ft/30 m length, 100 sensors,  1 ft/30 cm spacing

1. Results show shear wave velocity versus depth up to 200 ft/61 m are consistent between Lines 1 and 2
2. The results show that there exists deep silt deposit, relatively uniform up to 200 ft/61 m 
3. Finally the bedrock is deeper than expected and not accessible by drilling or too expensive by this method.
4. Bedrock position is 220ft/67 m deep.