Application of Gravity and Radon Studies to Delineate the Concealed Section of the Khisor Thrust
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Radon concentration, a geochemical parameter of naturally occurring noble gas and potential relative gravity field variation, has been studied in the current investigations. These investigations were carried out along and in proximity to the Khisor Thrust in the Trans Indus ranges marking the southern boundary of Bannu basin in Pakistan. The studies were aimed to demark the concealed section of the thrust fault beyond termination of its surface signature. The consistent increasing pattern of radon variation while approaching the approximate location of fault and decrease while moving farther from it suggests the existence of a fault to the subsurface, which should be verified through gravity studies. Variation of radon concentration between 2.5 and 4.1 kBq/m3 was observed on or near the fault zone in exposed and concealed segments, whereas the lower bound variation of 1.1–2 kBq/m3 was encountered on points moving away from fault zone. This variation of radon concentration promisingly supported the idea of the existence of a fault zone beyond the cessation of surface signature. The argument was further validated through the relative gravity variation studies following the radon concentration. The Bouguer anomaly was calculated along all 16 profiles cross-cutting the fault zone. The regional gravity mapped along 231 points of investigation showed a variation between − 90 and 8 mGal. The residual gravity highlighting the effects of upper crust disturbance because of under-thrusting has shown anomalous values between − 11 and 18 mGal. The results when contoured have shown a good congruence with those received from radon concentration contrasts. Conclusively, it can be perceived that these two nondestructive and less laborious techniques work in composite usefully to delineate the unseen earthquake potential source.
KeywordsGravity studies radon anomalies Khisor Thrust Trans Indus earthquake
The authors are thankful to two anonymous reviewers for their useful comments about the manuscript betterment. The authors would like to extend thanks to Mr. Haseeb Ur Rahman Hashmi (P.S.) and Mr. Razi Haider (P.S.) from AEMC, Lahore, Pakistan for their support and guidance about gravity data interpretation. Mr. Waqar Ali Zafar would like to pay special gratitude to Mr. Raees Amjad & Toseef Ahmed from Bahria University, Islamabad, Pakistan, for constructive discussion about structural evaluations. Efforts of ex and current students at CES, Asma Nabi Bakhsh, Kausar Majeed and Asad are also acknowledged thankfully.
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for profit sectors.
- AlphaGUARD portable radon monitors user manual, Instruments Germany, 1998Google Scholar
- Awais, M., Barkat, A., Ali, A., Rehman, K., Zafar, W. A., & Iqbal, T. (2017). Satellite thermal IR and atmospheric radon anomalies associated with the Haripur earthquake (Oct 2010; 5.2). Pakistan. Advances in Space Research, 60(11), 2333–2344. https://doi.org/10.1016/j.asr.2017.08.034.CrossRefGoogle Scholar
- Baixeras, C., Bach, J., Amgarou, K., Moreno, V. and Font, L. (2005). Radon levels in the volcanic region of La Garrotxa, Spain. Radiation Measurements. 40(2), 509–512. https://doi.org/10.1016/j.radmeas.2004.12.024.
- Barchi, M. (1998). The CROP 03 profile: a synthesis of results on deep structures of the Northern Apennines. Mémoires de la Société Géologique de France, 52, 383–400.Google Scholar
- Ciotoli, G., S. Lombardi, et al. (2007). “Geostatistical analysis of soil gas data in a high seismic intermontane basin: Fucino Plain, central Italy.” Journal of Geophysical Research: Solid Earth 112(B5) https://doi.org/10.1029/2005JB004044
- Hemphill, W. R., & Kidwai, A. H. (1973). Stratigraphy of the Bannu and Dera Ismail Khan areas, Pakistan (No. 716-B).Google Scholar
- Javed, F., Hainzl, S., Aoudia, A., & Qaisar, M. (2016). Modeling of Kashmir Aftershock Decay Based on Static Coulomb Stress Changes and Laboratory-Derived Rate-and-State Dependent Friction Law. Pure and Applied Geophysics, 173(5), 1559–1574. https://doi.org/10.1007/s00024-015-1192-9.CrossRefGoogle Scholar
- Kazmi, A. H., & Jan, M. Q. (1997). Geology and tectonics of Pakistan. Graphic publishers.Google Scholar
- Lillie, R. J., Johnson, G. D., Yousuf, M., Zamin, A. S. H., & Yeats, R. S. (1987). Structural development within the Himalayan foreland fold-and-thrust belt of Pakistan.Google Scholar
- Manual, C. G. (2009). CG-5 Scintrex autograv system operation manual.Google Scholar
- Murray, A. S., & Tracey, R. M. (2001). Best practice in gravity surveying. Geoscience Australia, 3, 5.Google Scholar
- Robinson, E. S. (1988). Basic exploration geophysics. New York: Wiley.Google Scholar
- Scarascia, S., Cassinis, R., et al. (1998). Gravity modelling of deep structures in the Northern-Central Apennines. Mémoires de la Société Géologique de France, 52, 231–246.Google Scholar
- Somlai, K., Tokonami, S., Ishikawa, T., Vancsura, P., Gáspár, M., Jobbágy, V., et al. (2007). 222Rn concentrations of water in the Balaton Highland and in the southern part of Hungary, and the assessment of the resulting dose. Radiation Measurements, 42(3), 491–495. https://doi.org/10.1016/j.radmeas.2006.11.005.CrossRefGoogle Scholar
- Vohat, P., Gupta, V., Bordoloi, T. K., Naswa, H., Singh, G., & Singh, M. (2013, November). Analysis of different interpolation methods for uphole data using Surfer software. In: 10th Biennial International Conference and Exposition (pp. 23–25).Google Scholar
- Yakut, H., Tabar, E., Yildirim, E., Zenginerler, Z., Ertugral, F., & Demirci, N. (2017). Soil gas radon measurement around fault lines on the western section of the North Anatolian fault zone in Turkey. Radiation Protection Dosimetry, 173(4), 405–413. https://doi.org/10.1093/rpd/ncw009.Google Scholar