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Relationship between seismicity and active faults in Thanh Hoa province detected by local seismic network

Duong T. N., Lai Hop Phong, Pham D. N., Chen C. H., Dinh V. T.

Abstract


Thanh Hoa province belongs to the southwest part of Northwest Vietnam, which is considered a tectonically active region. In the area of Thanh Hoa province, there are three deep-seated tectonic faults, namely Son La-Bim Son, Song Ma, and Sop Cop. As predicted by scientists, these faults are capable of producing credible earthquakes that might be the strongest in the territory of Vietnam. Besides the three main seismogenic sources, in the province, there are other smaller active faults such as Thuong Xuan-Ba Thuoc and Thuong Xuan-Vinh Loc but the relationship of these faults with seismic activity is still rather blurred. This may due to the sparseness of the Vietnamese National Seismic Network which can not record adequately small earthquakes in the area. This paper presents new results of additional monitoring from a local seismic network using 12 Guralp - 6TD broadband seismometers that have been deployed in Thanh Hoa province since November 2009. We found that the Thanh Hoa area is not seismically quiet. The average number of earthquakes recorded by the network has reached 80 - 90 events per year and some of them have magnitude from ML 3.0 to 4.0.

By integration of the earthquake epicenters derived from the local network and distribution of active faults, we can detect several earthquakes locating near the three active faults, not only along the main faults but also along its subsidiary faults. We focused on the active faults of Thuong Xuan-Ba Thuoc and Thuong Xuan-Vinh Loc by using the recent results of the gravity, seismic, and magnetotelluric data analyses. Several recorded earthquakes distribute along the two small faults and some of them reach magnitude 3.0 or greater on the ML scale. In this study, the Thuong Xuan-Vinh Loc is recognized as a seismogenic source. To identify seismic hazard potential caused by earthquakes generated from the active faults, segmentation of the Thuong Xuan - Ba Thuoc fault had been done based on geological and geomorphological indications and seismic activity, and then the peak ground acceleration was determined for each fault segment. Besides, a large number of earthquake epicenters do not have a good correlation with a specific fault, especially in the area of Thanh Hoa coastal plain, which is covered by thick layers of Neogene - Quaternary sediment. This shows that there may be hidden active faults in the area which are needed to study further.


Keywords


Seismic activity, active fault, local seismic network, Thanh Hoa

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References


Bui V.T., Nguyen V.H., Oneta S., Samsanith D., Soutthiphong V., Bounpaphan M., 2014. Active characteristics of Sam Nua fault zone during Neotectonic stage. Vietnam J. Earth Sci., 36(2), 97-107 (in Vietnamese).

Campbell K.W., 1997. Empirical near-source attenuation relationships for horizontal and vertical components of peak ground acceleration, peak ground velocity, and pseudo-absolute acceleration response spectra, Seism. Res. Lett., 68, 154-179.

Dinh V.T. et al., 2010. Study of the earth crustal structures of Northern Vietnam by using the deep seismic, magnetotelluric investigations and gravity data. Vietnam National project: KC08.06/06-10: Outcome report - 8/2010 (in Vietnamese).

Dinh V.T. et al., 2012. Study in detail of the seismic activity of the Song Ma fault zone (Along the Thanh Hoa - Nghe An Section) and characteristics of several soil dynamic parameters in the social-economic important locations of the study area. Vienam Academy of Science and Technology project (2010-2011), Outcome report - 5/2012 (in Vietnamese).

Dinh V.T., Chen C.H., Wen S., Lai H.P., Tran A.V., Nguyen T.H.Q., Duong T.N., 2013. The preliminary results of earthquake observation by deployment of the local seismic network Guralp - 6TD in the region of Thanh Hoa province. Vietnam J. Earth Sci., 35(1), 36-46 (in Vietnamese).

Dinh V.T., Harder S., Huang B.S., Trinh V.B., Doan V.T., Lai H.P., Tran A.V., Nguyen T.H.Q., Nguyen V.D., 2018. An overview of northern Vietnam deep crustal structures from integrated geophysical observations. Terr.Atmos.Ocean. Sci., 29, 1-16.

Douglas J., 2011. Ground-motion prediction equations 1964-2010. Final Report BRGM/RP-59356-FR. Geoscience for a sustainable Earth.

Lai H.P., 2016. The crustal structural model of Northern Vietnam based on seismic and gravity data. PhD. Dissertation, Institute of Geological Sciences, VAST (in Vietnamese).

Lai H.P. et al., 2018. The detailed characteristics of seismic activity in the Thuong Xuan-Ba Thuoc fault zone and related geological hazards. Vietnam Academy of Science and Technology project VAST05.01/15-16, Outcome report-6/2018 (in Vietnamese).

Langston C.A., 1979. Structure under Mount Rainier, Washington, inferred from teleseismic body waves. Journal of Geophysical Research, 84, 4749–4762.

Lee W.H.K., J.C. Larh, 1972. HYPO71: a computer program for determining hypocenter, magnitude, and the first motion pattern of local earthquakes, USGS, Open-File report, 29pp.

Lee W.H.K., C.M. Valdes, 1985. HYPO71PC: a personal computer version of the HYPO71 earthquake location program, USGS, Open-File report, 85-749, 43pp.

Lee S.K., Kim H.J., Song Y., Lee C.K., 2009. MT2DinvMatlab - A program in MATLAB and FORTRAN for two-dimensiona magnetotelluric inversion, Computers and Geosciences, 35(8), 1722-1734.

Mark R.K., 1977. Application of linear statistical model of earthquake magnitude versus fault length in estimating maximum expectable earthquakes. Geology, 5, 464-466.

Nguyen D.X. et al., 2004. Earthquake and ground motion prediction in the territory of Vietnam. Vietnam National project (in Vietnamese).

Nguyen D.X., 2009. Earthquakes in the territory of Vietnam. In the book: Cenozoic dynamics of Northen Vietnam for celebrating 10 years of the Vietnam-Poland cooperation (1999-2009), 165-177 (in Vietnamese).

Nguyen H.P., Pham T.T., 2015. Probabilistic seismic hazard maps of Vietnam and the East Vietnam sea. Vietnam J. of Marine Science and Technology, 15(1), 77-90 (in Vietnamese).

Nguyen N.T. et al., 2006. Detailed earthquake zonation of the Northwest Region. Vietnam National project: 2007-48-129 (in Vietnamese).

Nguyen T.Y. et al., 1998. Study of the land cracking hazard of the Vietnam territory. Vietnam National project: DL-94, Outcome report (in Vietnamese).

Nguyen T.Y. et al., 2014. Investigation and establishing Natural Hazard Maps of Lao DPR. Outcome Report of Vietnam-Laos cooperation research in framework of Vietnam-Laos Protocol Agreement 2011-2014, Institute of Geological Sciences, VAST, Hanoi (in Vietnamese).

Nguyen V.D., Huang B.S., Le T.S., Dinh V.T., Zhu L., Wen K.L, 2013. Constrains on the crustal structure of northern Vietnam based on analysis of teleseismic converted waves. Tectonophysics, 601, 87- 97.

Nguyen V.H., Nguyen N.T., Hoang Q.V., 1996. Some characteristics of the young NW - SE trending fault systems in the Vietnam Northwest Region. In the book: Geology and Resources, Hanoi. Science and Technique Pub. House, 1, 47-58 (in Vietnamese).

Nguyen V.H., 2002. Characteristics of the neotectonic faults in the Northwest Region of Vietnam. Ph.D. Dissertation-Institute of Geological Sciences, VAST (in Vietnamese).

Nguyen V.H., Hoang Q.V., 2004. About activity of the neotectonic fault zones in Northwest Region of Vietnam. Vietnam J. of Geology, 285, 38-48 (in Vietnamese).

Nguyen V.H., Hoang Q.V., 2006. The main characteristics of the Son La - Bim Son fault zone in the Neotectinic stage. Journal of Natural Science and Technology, Hanoi National University, XXII(2A), 21-39 (in Vietnamese).

Nguyen V.H., Hoang Q.V., 2009. The main characteristics of the Song Ma fault zone in the Neotectonic stage. Vietnam J. of Geology, 7, 21-39 (in Vietnamese).

Pham N.D., Pham N.K., Lai H.P., Dinh V.T., Tran A.V., Duong T.N., Ngo T.L., 2018. The effectiveness of data analysis by using the differential magnetotelluric curves in the study of deep structures. Journal of Geological and Minning Engineering Science, 59(2), 18-26 (in Vietnamese).

Phung V.P., Vu V.C., 2002. The dynamic characteristics of the Ninh Binh-Thanh Hoa region. The proceedings of the Workshop on Earthquakes and several other natural hazards in the Northwest Region of Vietnam. Pub. of Hanoi National University, 155-165 (in Vietnamese).

Shuka J., Choudhury D., 2012. Estimation of seismic ground motions using deterministic approach for major cities og Gujarat. Nat. Hazards Earth Syst. Sci., 12, 2019-2037.

Su C.M., Wen S., Tang C.C., Yu L.Y., Chen C.H., 2018. The variation of crustal structure along the Song Ma Shear Zone, Northern Vietnam. Tectonophysics, 734-735, 119-129.

Thorne L., Terry C.W., 1995. Modern global Seismology. Academic Press. Inc., San Diego, California, 521pp.

Tran T.H. et al., 2002. Study and assess all types of geohazards in the Vietnam territory and measures of prevention (First Stage for Northern part of Central Region ). Vietnam National project (2000-2001), Outcome Report-2002, Institute of Geological Sciences, VAST (in Vietnamese).

Tran T.H. et al., 2004: Study and assess different types of geohazards in the mountainous provinces of Northern Vietnam and solutions of prevention, Vietnam National project (2002-2003), Outcome Report-2004, Institute of Geological Sciences, VAST (in Vietnamese).

Tran V.T. et al., 2011. Study the relationship between different types of geohazards and modern activity of the sub meridian fracture zones in the Northwest region of Vietnam. Vietnam Academy of Science and Technology project (2009-2010), outcome report-2011, Institute of Geological Sciences (in Vietnamese).

Wells D.L., Kevin J.C., 1994. New empirical relations among magnitude, rupture length, ruture width, rupture area, and surface displacement. Bulletin of the Seismological Society of America, 84(4),

-1002.

Wen S., Tang C.C., Yu L.Y., Lai H.P., Dinh V.T., Chang W.Y., Chen C.H., 2015. The Tectonic Structures of the Song Ma Fault Zone, Vietnam. J. of Asian Earth Sciences, 107, 26-34.

Wu W.J., Wen S., Tang C.C., Yu L.Y., Lai H.P., Dinh V.T., Chen C.H., 2018. Seismogenic structures in the Ma River Fault Zone, Vietnam: Insights from Focal Mechanisms of Microearthquakes and local stress state. Bulletin of the Seismological Society of America, 108(6), 3260-3269.




DOI: https://doi.org/10.15625/0866-7187/15931 Display counter: Abstract : 70 views. PDF : 6 views.

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Vietnam Journal of Earth Sciences, ISSN: 0866-7187; 2615-9783

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