Seismic Imaging with a Hammer Drilling Source: SIHDS

Purpose and goal

The goal of the feasibility study was to test if the signals from the Wassara hammer could be used for seismic imaging of the surrounding rock. The hammer hits during drilling should generate strong seismic signals in the rock. A test next to the Wassara factory with drilling down to 270 m shows that it is possible to use the hammer hits as a seismic source. Seismograms generated by correlation with the pilot signal from the hammer have a higher signal to noise ratio than those using a surface sensor. One problem is the exact timing of the hammer hits.

Expected results and effects

The test measurements show that it is possible to use the hammer hits as a seismic source. Further testing needs to be done over an area where there exists know structures that reflect seismic waves. Furthermore, the time synchronization of the pilot signal with the recording system needs to be improved.

Planned approach and implementation

At a meeting with Wassara the test measurements were using their drilling rig. The measurements were performed in early October just outside the back of the Wassara factory. The unit for registering the pilot signal from the hammer hits was connected to the drilling rig. Uppsala installed 84 stations for measuring ground velocity while drilling. Data from these stations were processed and correlated with the pilot signal and some selected surface stations.