- Email: [email protected]
Reply to comments on “Detection of active faults using EMR-technique and cerescope at Landau area in central Upper Rhine Graben, SW Germany”
APPGEO-02910; No of Pages 3 Journal of Applied Geophysics xxx (2016) xxx–xxx
Contents lists available at ScienceDirect
Journal of Applied Geophysics journal homepage: www.elsevier.com/locate/jappgeo
Reply to comments on “Detection of active faults using EMR-technique and cerescope at Landau area in central Upper Rhine Graben, SW Germany” W. Hagag a,⁎, H. Obermeyer b a b
Benha University, Faculty of Science, Geology Department, Post Code: 13518 Benha, Egypt Company of exploration and radiolocation (GE&O), Südbeckenstraße 14-20a, D.76189 Karlsruhe, Germany
A R T IC L E
IN F O
Article history: Received 24 January 2016 Received in revised form 25 January 2016 Accepted 28 January 2016 Available online xxxx Keywords: Reply EMR-method Cerescope
Reply: The author built his comments on our paper on the results of Krumbholz (2010) and Krumbholz et al. (2012) which we have critical comments on them. As these comments have a great significance to this discussion, we will summarize them and then the inquiries of the author concerning our paper will be addressed. 1. Comments on Krumbholz (2010) 1. The first and second case-studies in this work were supporting the EMR-technique using cerescope, whereas the author disregarded their results even he did not discuss why they were successful. The first case study was in SE Sweden and its results confirmed the applicability of the EMR-method as a tool to determine the orientation of the main horizontal stress (σ H). The second case study in SE Sweden and central Germany tested the possibility to detect active faults and fault zones with the EMR-method and compared between the method and the Radon method. Here also the results were supporting the applicability of the EMRtechnique. 2. The author considered in his work the basic approach of the EMRmethod and recommended further check and development for the
⁎ Corresponding author. E-mail addresses: [email protected] (W. Hagag), [email protected] (H. Obermeyer).
method. However, in Krumbholz et al. (2012) the author worked against the origin of the EMR-method at all. 3. In the third case-study the investigated area was very large (280,000 km2) and however covered with only 52 horizontal measurements in order to determine the directions of the main horizontal stress and correlate them with the data published on the World Stress Map (WSM) of Heidbach et al. (2008). We suppose that the spatial resolution and the behavior of the EMR-properties given by the author were inaccurate because of: (a) the direction of the main horizontal stress should be changed all over this huge area with the change of the structural and tectonic setting from a region to another, beside that the change of the EMR-characters would be related to whether these regions were active. Furthermore, the stress data on the WSM are mainly acquired from the boreholes, subsurface breakouts, from the deep geophysical prospecting methods and earthquakes, whereas the stress data obtained from the EMRmethod and cerescope depend on the surface detection and measurements. Accordingly, the correlation between the two datasets is improper. That is because the principal normal stresses known to be rotated with depth and hence the stress trajectories would be not the same in the two cases. The change of direction of normal stresses from subsurface to surface settings could be easily explained in the framework of the modern concept of Brittle–Ductile Transition (BDT), which controls the seismic cycle and hence faulting activity within the upper crustal levels (Doglioni et al., 2015). Additionally, the author in chapter 5 (page 101) stated that the error in the data on the WSM ranges between ± 15° and ± 40°, while in EMRdirections the error is only between ± 5° and ± 10° which makes the correlation between them is arbitrary as they are not on the same level of accuracy. (b) Concerning the linear profiles, they were so regional and the frequency range of the device was fixed on 30–35 kHz, a very restricted band. See Fig.5.1. 4. Why the author proposed a common center near Emden (page 95) for the arc-shape like data of the main horizontal stresses as the main source of the EMR-signals, where DH035/DH038 transmitter affected the EMR-dataset? The suggested center may represent the position of an axis of rotation of the North Germany Craton or subplate. Was the author check the velocity or strain vectors derived from the GPS studies on crustal movements in North Germany? They often take the same parabolic shape. The most prominent
http://dx.doi.org/10.1016/j.jappgeo.2016.01.024 0926-9851/© 2016 Elsevier B.V. All rights reserved.
Please cite this article as: Hagag, W., Obermeyer, H., Reply to comments on “Detection of active faults using EMR-technique and cerescope at Landau area in central Upper Rhine Graben,..., Journal of Applied Geophysics (2016), http://dx.doi.org/10.1016/j.jappgeo.2016.01.024
2
W. Hagag, H. Obermeyer / Journal of Applied Geophysics xxx (2016) xxx–xxx
geomorphological and satellite lineations in northern Germany are associated with basement faults and even with crustal or lithospheric discontinuities (Reickerter et al., 2005), whereas Röckel and Lempp (2003) and Reinecker et al. (2004) realized that the compilation of stress data obtained from borehole breakouts, hydro-fractures and earthquakes inferred maximum horizontal stress fan and swing from NW direction in the west to NNE in the east in the area between Hamburg and Berlin (almost the area discussed in Krumbholz (2010)). These facts demonstrate that the stress data obtained from the EMR-technique in the study of Krumbholz (2010) correspond well with the regional stress trajectories recorded by different methods (in Fig. 5.6 the EMR stress vectors coincide in many areas with the data on the WSM), which support against the author conclusions. 5. In Table 5.2, the frequency of most of the VLF transmitters is ranging from 14.5 kHz to 29 kHz, whereas most of the EMR-measurements were recorded while the cerescope device adjusted on frequency range between 30 and 35 kHz. How the author supposed the effect of these VLF transmitters on the EMR dataset? 6. We tested the cerescope antenna in the laboratories of the G&EO Karlsruhe and the most sensitive part was at its tip, not its ‘broadside’ as stated by the author. 7. The author never cited any reference supporting or described the VLF method proposed in his work as an alternative method for the EMR-technique. 2. Comments on Krumbholz et al. (2012) This research paper was mainly depends on the studies of Krumbholz (2010), which have been commented above. Furthermore, the VLF method advocated by the authors was based mainly on two Ph.D theses; Bastani (2001) and Persson (2001), where both were carried out in Uppsala University of Sweden. However, the author did not give any known published works that describe the basic principles and the physical theory, where the VLF method was derived from. Additionally, these works were discussing the controlled source/radio magnetotelluric system or what so-called RSRMT-method and were not compared between this method and the EMR-method and even not considered the VLF-method proposed by the authors. 3. The paper of Landau, the EMR-method and EMR-technology 1. Hagag and Obermeyer (2016) did not ignore any previous works concerning EMR-method on the Landau area. Krumbholz (2010) was cited in this study as a previous study applied the EMRmethod successfully in two case-studies. However, Krumbholz et al. (2012) was mainly based on the results introduced in Krumbholz (2010) that we have a critical comment on them as discussed above. 2. VLF method was introduced in Krumbholz (2010) and Krumbholz et al. (2012) for the first time without discussing a theoretical background of the method or citing any widely accepted publications supporting the method. Furthermore, the VLF method is not wellknown as stated by the author(s). 3. The comments of the author on the EMR-method and its applicability were discussed in detail in the above discussion. 4. Concerning the author comments on the polar diagrams, Hagag and Obermeyer (2016) proposed that there are a two conjugated sets of fractures when they were analyzed an N to NNE direction of maximum horizontal stress was estimated. The complex pattern of the recorded EMR-emissions on the polar diagrams reflects the strong activity (hydro-fracturing) of the study area, where a secondary stress pattern owing to the reactivation of the old rift-related faults resulted in a newly formed system of fractures follows the old trends. 5. Concerning the EMR-linear profiles measured during our study at Landau area, the accuracy of the resulted data on the faults and
their strike interpreted from these profiles was moderate to high. The heavier the network of linear profiles, the more accurate data obtained based on their interpretation. 6. We tested the EMR-method in some areas in Germany and Egypt, and the resulted data were very convincing and easy for interpretation in the framework of the structure and tectonics of such areas. Beside Landau area in SW Germany, an area in Eiffel in northern Germany was surveyed by the cerescope device and most of the profiles were suggesting a very low activity in such area except one profile. Is there in Eiffel no VLF transmitter existed to make the EMRdataset more positive than that recorded? In northern Egypt as well the EMR-method has been checked by Wael Hagag in a most active seismogenic zone in northern Egypt (Cairo–Suez district) and the measured linear profiles and horizontal stress data were very correspond to the seismotectonic activity of this area. In the same context, in southern Egypt and along the Kalabsha fault zone which considered the most active wrench fault in southern Egypt, the measured profiles were also clear and confirming the activity along such zone. The obtained data are now the subject of two research papers currently under development. 7. As known, some fault segments of the rift shoulders of the Upper Rhine Graben still active and the entire graben is characterized by high heat flow and is a proper site for geothermal industry. Enhanced Geothermal System (EGS) at Landau area suggested in several works to have a great impact on the seismic activity of the area, where the small shocks were felt by people in Landau city. Our EMR-study at Landau was promising and considered the first attempt to detect and monitor such activity, which is mostly attributed to reactivation of the old major fractures of the URG by hydro-fracturing processes carried out in the geothermal power plant at Landau area. Our study at Landau area considered a good start for surface detection of the fault-activity and associated seismic risk in this part from the URG. The EMR-method is an easy and applied method for this task but it needs further development. 8. In China, Peking University at Beijing developed a device like the cerescope using a new passive ultra-low frequency electromagnetic detection mechanism in a Coal Bed Methan (CBM) exploration (Qiming et al., 2008). An interesting observation is that the basic principles or the origin of this mechanism and that device is the same as that of the cerescope and the EMR-method, based on rock fracturing mechanism. Furthermore, the study on technology of electromagnetic radiation as a sensitive index to forecast the coal and gas hazards by Wu and Li (2010) gave a good sign on applicability of the EMR-monitoring technology in the field of surface detection and also in underground mining forecast processes. Wang et al. (2013) considered the role of EMR-detectors like KBD5 and KBD7 in effective and accurate early warning as elementary basis for the efficient and affordable prevention and control of coal and rock dynamic disasters such as coal and gas outbursts, rock bursts, monitor roof stability and observe pressure of the surrounding rocks. All of these studies predict a good future success for the EMR-technology in the field of geophysical prospecting and exploration and as an accurate rock failure detection mechanism. Acknowledgments The authors thank Dr. Michael Krumbolz for his comments on their publication and for giving a way to this fruitful discussion about an important EMR-method and technology. Thanks are also extending to the editor Dr. Xia for his great suggestion to publish this discussion through his much respected journal (J. of Applied Geophysics). References Bastani, M., 2001. A new controlled source/radio magnetotelluric system (Ph.D. thesis) University of Uppsala, Sweden (179 pp.).
Please cite this article as: Hagag, W., Obermeyer, H., Reply to comments on “Detection of active faults using EMR-technique and cerescope at Landau area in central Upper Rhine Graben,..., Journal of Applied Geophysics (2016), http://dx.doi.org/10.1016/j.jappgeo.2016.01.024
W. Hagag, H. Obermeyer / Journal of Applied Geophysics xxx (2016) xxx–xxx Doglioni, C., Barba, S., Carminati, E., Riguzzi, F., 2015. Fault on–off versus strain rate and earthquakes energy. Geosci. Front. 6, 265–276. Hagag, W., Obermeyer, H., 2016. Detection of active faults using EMR-technique and cerescope at Landau area in central Upper Rhine Graben, SW Germany. J. Appl. Geophys. 124, 117–129. Heidbach, O., Tingay, M., Barth, A., Reinecker, J., Kurfeß, D., Müller, B., 2008. The World Stress Map Database Release 2008. http://dx.doi.org/10.1594/GFZ.WSM.Rel2008 (available online at www.world-stress-map.org). Krumbholz, M., 2010. Electromagnetic Radiation as a Tool to Determine Actual Crustal Stresses—Applications and Limitations (Ph.D. thesis) University of Göttingen, Germany (151 pp.). Krumbholz, M., Bock, M., Burchardt, S., Kelka, U., Vollbrecht, A., 2012. A critical discussion of the electromagnetic radiation (EMR) method to determine stress orientations within the crust. Solid Earth 3, 401–414. Persson, L., 2001. Plane wave electromagnetic measurements for imaging fracture zones (Ph.D. thesis) University of Uppsala, Sweden (132 pp.). Qiming, Q., Baishou, L., Peijun, L., Zexun, Z., Xia, Y., Rongbo, C., 2008. Passive ultra-low frequency electromagnetic detection technology for coal bed methane and its
3
application. Inter. Arch. of Photogr., Rem. Sens. and Spat. Inform. Sci., v. XXXVII, Part B8, Beijing, China. Reickerter, K., Kaiser, A., Stackebrandt, W., 2005. The post-glacial landscape evolution of the North German Basin: morphology, neotectonics and crustal deformation. Int. J. Earth Sci. 94, 1083–1093. Reinecker, J., Heidbach, O., Müller, B., 2004. World Stress Map Release 2004 (Worldwide web address: www.world-stress-map.org). Röckel, T., Lempp, C., 2003. Der spannungszustand im norddeutschen becken. Erdöl Erdgas Kohle 119, 73–80. Wang, E., Liu, Z., Li, Z., Liu, Z., He, Z., 2013. Application of electromagnetic radiation (EMR) technology in monitoring and warning of coal and rock dynamic disasters. Proceed. 22nd MPES Conf., Dresden, Germany, 14th–19th October 2013, pp. 561–568 http:// dx.doi.org/10.1007/978-3-319-02678-7-54. Wu, Y., Li, W., 2010. Study on technology of electromagnetic radiation of sensitive index to forecast the coal and gas hazards. Procedia Eng. 7, 327–334.
Please cite this article as: Hagag, W., Obermeyer, H., Reply to comments on “Detection of active faults using EMR-technique and cerescope at Landau area in central Upper Rhine Graben,..., Journal of Applied Geophysics (2016), http://dx.doi.org/10.1016/j.jappgeo.2016.01.024
Contents lists available at ScienceDirect
Journal of Applied Geophysics journal homepage: www.elsevier.com/locate/jappgeo
Reply to comments on “Detection of active faults using EMR-technique and cerescope at Landau area in central Upper Rhine Graben, SW Germany” W. Hagag a,⁎, H. Obermeyer b a b
Benha University, Faculty of Science, Geology Department, Post Code: 13518 Benha, Egypt Company of exploration and radiolocation (GE&O), Südbeckenstraße 14-20a, D.76189 Karlsruhe, Germany
A R T IC L E
IN F O
Article history: Received 24 January 2016 Received in revised form 25 January 2016 Accepted 28 January 2016 Available online xxxx Keywords: Reply EMR-method Cerescope
Reply: The author built his comments on our paper on the results of Krumbholz (2010) and Krumbholz et al. (2012) which we have critical comments on them. As these comments have a great significance to this discussion, we will summarize them and then the inquiries of the author concerning our paper will be addressed. 1. Comments on Krumbholz (2010) 1. The first and second case-studies in this work were supporting the EMR-technique using cerescope, whereas the author disregarded their results even he did not discuss why they were successful. The first case study was in SE Sweden and its results confirmed the applicability of the EMR-method as a tool to determine the orientation of the main horizontal stress (σ H). The second case study in SE Sweden and central Germany tested the possibility to detect active faults and fault zones with the EMR-method and compared between the method and the Radon method. Here also the results were supporting the applicability of the EMRtechnique. 2. The author considered in his work the basic approach of the EMRmethod and recommended further check and development for the
⁎ Corresponding author. E-mail addresses: [email protected] (W. Hagag), [email protected] (H. Obermeyer).
method. However, in Krumbholz et al. (2012) the author worked against the origin of the EMR-method at all. 3. In the third case-study the investigated area was very large (280,000 km2) and however covered with only 52 horizontal measurements in order to determine the directions of the main horizontal stress and correlate them with the data published on the World Stress Map (WSM) of Heidbach et al. (2008). We suppose that the spatial resolution and the behavior of the EMR-properties given by the author were inaccurate because of: (a) the direction of the main horizontal stress should be changed all over this huge area with the change of the structural and tectonic setting from a region to another, beside that the change of the EMR-characters would be related to whether these regions were active. Furthermore, the stress data on the WSM are mainly acquired from the boreholes, subsurface breakouts, from the deep geophysical prospecting methods and earthquakes, whereas the stress data obtained from the EMRmethod and cerescope depend on the surface detection and measurements. Accordingly, the correlation between the two datasets is improper. That is because the principal normal stresses known to be rotated with depth and hence the stress trajectories would be not the same in the two cases. The change of direction of normal stresses from subsurface to surface settings could be easily explained in the framework of the modern concept of Brittle–Ductile Transition (BDT), which controls the seismic cycle and hence faulting activity within the upper crustal levels (Doglioni et al., 2015). Additionally, the author in chapter 5 (page 101) stated that the error in the data on the WSM ranges between ± 15° and ± 40°, while in EMRdirections the error is only between ± 5° and ± 10° which makes the correlation between them is arbitrary as they are not on the same level of accuracy. (b) Concerning the linear profiles, they were so regional and the frequency range of the device was fixed on 30–35 kHz, a very restricted band. See Fig.5.1. 4. Why the author proposed a common center near Emden (page 95) for the arc-shape like data of the main horizontal stresses as the main source of the EMR-signals, where DH035/DH038 transmitter affected the EMR-dataset? The suggested center may represent the position of an axis of rotation of the North Germany Craton or subplate. Was the author check the velocity or strain vectors derived from the GPS studies on crustal movements in North Germany? They often take the same parabolic shape. The most prominent
http://dx.doi.org/10.1016/j.jappgeo.2016.01.024 0926-9851/© 2016 Elsevier B.V. All rights reserved.
Please cite this article as: Hagag, W., Obermeyer, H., Reply to comments on “Detection of active faults using EMR-technique and cerescope at Landau area in central Upper Rhine Graben,..., Journal of Applied Geophysics (2016), http://dx.doi.org/10.1016/j.jappgeo.2016.01.024
2
W. Hagag, H. Obermeyer / Journal of Applied Geophysics xxx (2016) xxx–xxx
geomorphological and satellite lineations in northern Germany are associated with basement faults and even with crustal or lithospheric discontinuities (Reickerter et al., 2005), whereas Röckel and Lempp (2003) and Reinecker et al. (2004) realized that the compilation of stress data obtained from borehole breakouts, hydro-fractures and earthquakes inferred maximum horizontal stress fan and swing from NW direction in the west to NNE in the east in the area between Hamburg and Berlin (almost the area discussed in Krumbholz (2010)). These facts demonstrate that the stress data obtained from the EMR-technique in the study of Krumbholz (2010) correspond well with the regional stress trajectories recorded by different methods (in Fig. 5.6 the EMR stress vectors coincide in many areas with the data on the WSM), which support against the author conclusions. 5. In Table 5.2, the frequency of most of the VLF transmitters is ranging from 14.5 kHz to 29 kHz, whereas most of the EMR-measurements were recorded while the cerescope device adjusted on frequency range between 30 and 35 kHz. How the author supposed the effect of these VLF transmitters on the EMR dataset? 6. We tested the cerescope antenna in the laboratories of the G&EO Karlsruhe and the most sensitive part was at its tip, not its ‘broadside’ as stated by the author. 7. The author never cited any reference supporting or described the VLF method proposed in his work as an alternative method for the EMR-technique. 2. Comments on Krumbholz et al. (2012) This research paper was mainly depends on the studies of Krumbholz (2010), which have been commented above. Furthermore, the VLF method advocated by the authors was based mainly on two Ph.D theses; Bastani (2001) and Persson (2001), where both were carried out in Uppsala University of Sweden. However, the author did not give any known published works that describe the basic principles and the physical theory, where the VLF method was derived from. Additionally, these works were discussing the controlled source/radio magnetotelluric system or what so-called RSRMT-method and were not compared between this method and the EMR-method and even not considered the VLF-method proposed by the authors. 3. The paper of Landau, the EMR-method and EMR-technology 1. Hagag and Obermeyer (2016) did not ignore any previous works concerning EMR-method on the Landau area. Krumbholz (2010) was cited in this study as a previous study applied the EMRmethod successfully in two case-studies. However, Krumbholz et al. (2012) was mainly based on the results introduced in Krumbholz (2010) that we have a critical comment on them as discussed above. 2. VLF method was introduced in Krumbholz (2010) and Krumbholz et al. (2012) for the first time without discussing a theoretical background of the method or citing any widely accepted publications supporting the method. Furthermore, the VLF method is not wellknown as stated by the author(s). 3. The comments of the author on the EMR-method and its applicability were discussed in detail in the above discussion. 4. Concerning the author comments on the polar diagrams, Hagag and Obermeyer (2016) proposed that there are a two conjugated sets of fractures when they were analyzed an N to NNE direction of maximum horizontal stress was estimated. The complex pattern of the recorded EMR-emissions on the polar diagrams reflects the strong activity (hydro-fracturing) of the study area, where a secondary stress pattern owing to the reactivation of the old rift-related faults resulted in a newly formed system of fractures follows the old trends. 5. Concerning the EMR-linear profiles measured during our study at Landau area, the accuracy of the resulted data on the faults and
their strike interpreted from these profiles was moderate to high. The heavier the network of linear profiles, the more accurate data obtained based on their interpretation. 6. We tested the EMR-method in some areas in Germany and Egypt, and the resulted data were very convincing and easy for interpretation in the framework of the structure and tectonics of such areas. Beside Landau area in SW Germany, an area in Eiffel in northern Germany was surveyed by the cerescope device and most of the profiles were suggesting a very low activity in such area except one profile. Is there in Eiffel no VLF transmitter existed to make the EMRdataset more positive than that recorded? In northern Egypt as well the EMR-method has been checked by Wael Hagag in a most active seismogenic zone in northern Egypt (Cairo–Suez district) and the measured linear profiles and horizontal stress data were very correspond to the seismotectonic activity of this area. In the same context, in southern Egypt and along the Kalabsha fault zone which considered the most active wrench fault in southern Egypt, the measured profiles were also clear and confirming the activity along such zone. The obtained data are now the subject of two research papers currently under development. 7. As known, some fault segments of the rift shoulders of the Upper Rhine Graben still active and the entire graben is characterized by high heat flow and is a proper site for geothermal industry. Enhanced Geothermal System (EGS) at Landau area suggested in several works to have a great impact on the seismic activity of the area, where the small shocks were felt by people in Landau city. Our EMR-study at Landau was promising and considered the first attempt to detect and monitor such activity, which is mostly attributed to reactivation of the old major fractures of the URG by hydro-fracturing processes carried out in the geothermal power plant at Landau area. Our study at Landau area considered a good start for surface detection of the fault-activity and associated seismic risk in this part from the URG. The EMR-method is an easy and applied method for this task but it needs further development. 8. In China, Peking University at Beijing developed a device like the cerescope using a new passive ultra-low frequency electromagnetic detection mechanism in a Coal Bed Methan (CBM) exploration (Qiming et al., 2008). An interesting observation is that the basic principles or the origin of this mechanism and that device is the same as that of the cerescope and the EMR-method, based on rock fracturing mechanism. Furthermore, the study on technology of electromagnetic radiation as a sensitive index to forecast the coal and gas hazards by Wu and Li (2010) gave a good sign on applicability of the EMR-monitoring technology in the field of surface detection and also in underground mining forecast processes. Wang et al. (2013) considered the role of EMR-detectors like KBD5 and KBD7 in effective and accurate early warning as elementary basis for the efficient and affordable prevention and control of coal and rock dynamic disasters such as coal and gas outbursts, rock bursts, monitor roof stability and observe pressure of the surrounding rocks. All of these studies predict a good future success for the EMR-technology in the field of geophysical prospecting and exploration and as an accurate rock failure detection mechanism. Acknowledgments The authors thank Dr. Michael Krumbolz for his comments on their publication and for giving a way to this fruitful discussion about an important EMR-method and technology. Thanks are also extending to the editor Dr. Xia for his great suggestion to publish this discussion through his much respected journal (J. of Applied Geophysics). References Bastani, M., 2001. A new controlled source/radio magnetotelluric system (Ph.D. thesis) University of Uppsala, Sweden (179 pp.).
Please cite this article as: Hagag, W., Obermeyer, H., Reply to comments on “Detection of active faults using EMR-technique and cerescope at Landau area in central Upper Rhine Graben,..., Journal of Applied Geophysics (2016), http://dx.doi.org/10.1016/j.jappgeo.2016.01.024
W. Hagag, H. Obermeyer / Journal of Applied Geophysics xxx (2016) xxx–xxx Doglioni, C., Barba, S., Carminati, E., Riguzzi, F., 2015. Fault on–off versus strain rate and earthquakes energy. Geosci. Front. 6, 265–276. Hagag, W., Obermeyer, H., 2016. Detection of active faults using EMR-technique and cerescope at Landau area in central Upper Rhine Graben, SW Germany. J. Appl. Geophys. 124, 117–129. Heidbach, O., Tingay, M., Barth, A., Reinecker, J., Kurfeß, D., Müller, B., 2008. The World Stress Map Database Release 2008. http://dx.doi.org/10.1594/GFZ.WSM.Rel2008 (available online at www.world-stress-map.org). Krumbholz, M., 2010. Electromagnetic Radiation as a Tool to Determine Actual Crustal Stresses—Applications and Limitations (Ph.D. thesis) University of Göttingen, Germany (151 pp.). Krumbholz, M., Bock, M., Burchardt, S., Kelka, U., Vollbrecht, A., 2012. A critical discussion of the electromagnetic radiation (EMR) method to determine stress orientations within the crust. Solid Earth 3, 401–414. Persson, L., 2001. Plane wave electromagnetic measurements for imaging fracture zones (Ph.D. thesis) University of Uppsala, Sweden (132 pp.). Qiming, Q., Baishou, L., Peijun, L., Zexun, Z., Xia, Y., Rongbo, C., 2008. Passive ultra-low frequency electromagnetic detection technology for coal bed methane and its
3
application. Inter. Arch. of Photogr., Rem. Sens. and Spat. Inform. Sci., v. XXXVII, Part B8, Beijing, China. Reickerter, K., Kaiser, A., Stackebrandt, W., 2005. The post-glacial landscape evolution of the North German Basin: morphology, neotectonics and crustal deformation. Int. J. Earth Sci. 94, 1083–1093. Reinecker, J., Heidbach, O., Müller, B., 2004. World Stress Map Release 2004 (Worldwide web address: www.world-stress-map.org). Röckel, T., Lempp, C., 2003. Der spannungszustand im norddeutschen becken. Erdöl Erdgas Kohle 119, 73–80. Wang, E., Liu, Z., Li, Z., Liu, Z., He, Z., 2013. Application of electromagnetic radiation (EMR) technology in monitoring and warning of coal and rock dynamic disasters. Proceed. 22nd MPES Conf., Dresden, Germany, 14th–19th October 2013, pp. 561–568 http:// dx.doi.org/10.1007/978-3-319-02678-7-54. Wu, Y., Li, W., 2010. Study on technology of electromagnetic radiation of sensitive index to forecast the coal and gas hazards. Procedia Eng. 7, 327–334.
Please cite this article as: Hagag, W., Obermeyer, H., Reply to comments on “Detection of active faults using EMR-technique and cerescope at Landau area in central Upper Rhine Graben,..., Journal of Applied Geophysics (2016), http://dx.doi.org/10.1016/j.jappgeo.2016.01.024