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1. Is Your region appropriate for Passive surveys?

Microearthquakes occur almost everywhere; in most cases, micro seismicity is not detected by existing regional networks. LandTech engineers perform a background micro seismicity feasibility study before any passive seismic tomography survey to verify seismic activity and estimate the number of required seismographs and recording period.

Below, we present an example of a feasibility study over a 400 km² area located in the Zagros Mountains, Iran. During the pre-acquisition stage, a seismicity assessment was attempted, followed by a designation of the optimum parameters for the network configuration. A checkerboard test was performed to assess the resolution of the designed seismological network.

We created an artificial model below the entire exploration block by introducing various cubes with different seismic velocities within a homogeneous velocity media (checkerboard) and tried to recover the initial model inverting arrivals from synthetic seismographs to a varying number of seismological stations.

To get a general idea of the seismicity of your country, refer to the LandTech Seismicity Map.

2. What is the cost of a passive tomography investigation?

The average cost to investigate a region 10,000 km² with rough topography is less than the cost of a conventional gravity survey and is around $2 million, depending on local conditions (e.g. topography, accessibility). This cost drops considerably if the total area is larger; for instance, it can reduce to $4-5 million for an 8,000 km² mountainous area depending on the number of stations to be installed.

3. Are the data obtained less accurate than those of a conventional seismic reflection survey?

In many cases, they are even better, especially in regions with rough topography or complicated geology, where Passive Seismic Tomography (PST) can provide excellent results.

4. Why Passive surveys should be carried out at the initial exploration stages?

The exploration costs can be reduced significantly by identifying sub-regions of interest.

5. How long does it take to conduct a 3D passive investigation?

Typically, it takes around 6 months, depending on background seismicity. LandTech conducts free pre-feasibility desk research for optimal station number and project timeframe.

6. How can we be sure about the accuracy of the results?

PST results are crosschecked with VSP results and differ less than 5%. LandTech implements Quality Control Tests incorporating synthetic and inverse modeling.

7. What kind of equipment do you use?

LandTech designs and manufactures seismic recording instruments specifically for passive seismic tomography.

8. How many earthquakes are needed to be recorded for sufficient resolution?

With average background seismicity, surveys last between 5-8 months for optimal resolution.

9. How do you manage so many waveforms?

LandTech has developed algorithms for processing continuous seismological recordings, isolating microseismic events, and determining arrival times for seismic phase inversion.

10. What about the case where microearthquakes originate from active faults?

Seismographs can be relocated after a few months for complete ray coverage.

11. Do all microearthquakes need to originate within the area of interest?

Some seismographs are deployed outside the area to better locate nearby events to enhance resolution.

12. How long can a seismograph be operated in areas without electricity?

LandTech’s LTSR-24 digitizer can operate on a car battery for almost a month, with additional power options like solar panels and micro wind generators.

13. Can you apply this methodology in areas with rough topography?

PST methodology easily adapts to rough terrains without extensive equipment layout.

14. What about environmentally protected areas, swamps, tropical forests, etc.?

PST methodology is environmentally friendly and has been implemented successfully in sensitive regions.

15. Can you operate offshore?

LandTech has designed an Ocean Bottom Seismograph for offshore passive seismic tomography services.

16. Can PST methodology be applied where we have existing seismic data of poor quality?

PST results can improve the resolution of existing seismic sections.

17. Can we apply PST methodology to high noise areas?

Yes, with special installation procedures and noise filtering techniques.

18. Can you combine PST results with Gravity and MT surveys?

LandTech’s joint inversion methodologies combining PST, Gravity, and MT data have improved geological model resolution.

19. Can PST methodology differentiate oil and gas reservoirs?

Vp/Vs ratio is sensitive to pore fluid types, distinguishing gas saturation from liquid saturation.

20. Can PST methodology be used for shale fracking and reservoir monitoring?

LandTech has developed instrumentation for advanced monitoring without expensive boreholes.

21. Can we perform passive seismic tomography surveys over a very restricted area?

It's generally inadvisable to focus surveys on restricted areas due to inadequate recording.

22. How easy is it to interpret PST results?

Interpreting PST results is straightforward with Vp and Vp/Vs data.

23. How sure can LandTech be that the technology works?

Results have consistently been verified with multiple datasets across different basins.

24. Is there any relation between Low Frequency Passive Seismic method and LandTech’s PST method?

There is no relation; LandTech's PST method is evidence-based and proven effective.

25. Can PST be used to pinpoint hydrocarbon reservoir and drilling sites?

PST can identify sub regions high in probability for successful wells based on structural information.

26. What are your guarantees?

LandTech can provide letters of recommendation from satisfied clients.

27. How can you maintain a seismological network in a 100% recording state?

LandTech designs its own equipment ensuring prompt repairs for any faulty stations.