This step-by-step guide will take you through the process of collecting quality seismic data to undertake Vs30 analysis. This guide is optimized for mobile devices.
NOTE: Vs30 surveys require 4.5Hz vertical geophones
With the set-up wizard on the screen of the instrument, click start, below
Settings and field procedures are based on recommendations published by Park et al.
Click for more information
Select 24 channels in the Terraloc Set-up Wizard
(use single cable option for 48 channel instruments)
Select Vs30 from the drop-down menu
Select the green “NEXT” button
On the second page of the Terraloc Set-up Wizard, select 2m geophone spacing and hammer source
Press “OK”
This is a generic layout for a Vs30
measurement with 24 geophones.
If you have a 48 channel instrument,
use only the first cable to provide 24 channels.
Geophone spacing should be 2 metres
Place a spare geophone next to the shot plate and connect to the trigger reel. The far-end of the trigger reel should be plugged into the “Analog. Trig In” trigger connection on the instrument end-panel.
It is possible to use a wireless trigger connection, see here for more information.
Place a spare geophone next to the shot plate and connect to the trigger reel. The far-end of the trigger reel should be plugged into the “Analog. Trig In” trigger connection on the instrument end-panel.
It is possible to use a wireless trigger connection, see here for more information.
Open the Layout Geometry window by pressing 6 on the front panel of the instrument
Example shot record from a -48m off-end shot:
Update shot position to -24m in Layout Geometry
(press 6 on the front panel)
Example shot record from a -24m off-end shot:
Update shot position to -12m in Layout Geometry
(press 6 on the front panel)
Example shot record from a -12m off-end shot:
Update shot position to -2m in Layout Geometry
(press 6 on the front panel)
Example shot record from a -2m off-end shot 
Place shot plate 2m from the last geophone
Enter shot position as 48m in Layout Geometry
(press 6 on the front panel)
Remember: the distance entered is from the first geophone (0m in the spread)
Example shot record from a 2m off-end (48m) shot:
Update shot position to 58m in Layout Geometry
(press 6 on the front panel)
Example shot record from a 12m off-end shot:
Update shot position to 70m in Layout Geometry
(press 6 on the front panel)
Example shot record from a 24m off-end shot:
Update shot position to 94m in Layout Geometry
(press 6 on the front panel)
Example shot record from a 48m off-end shot:
Connect your phone via USB to the Terraloc Pro 2 and allow access on your device. The Terraloc will see your device as an external storage location, use the CTRL + SHIFT + LEFT ARROW shortcut to access the file explorer and move files across.
Using ALT + TAB will take you back to the Terraloc Pro 2 software.
Connect your USB drive to the Terraloc Pro 2 and this will be used as the destination for the Quick Backup function on the instrument.
Processing requires 3rd party inversion software such as Geogiga
Contact us for more information on processing packages
The 8 shots are processed individually, each creating a velocity model, these results are correlated to generate a combined velocity model, summarised by the Vs30 value.
(after BSSC, 1997*)
*Building Seismic Safety Council (BSSC), 1997, NEHRP, recommended provisions for seismic regulations for new buildings, Part 1-Provisions (FEMA Federal emergency Management Agency 302), 290 p.