Quantifying capability of a local seismic network in terms of locations and focal mechanism solutions of weak earthquakes
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Extension of permanent seismic networks is usually governed by a number of technical, economic, logistic, and other factors. Planned upgrade of the network can be justified by theoretical assessment of the network capability in terms of reliable estimation of the key earthquake parameters (e.g., location and focal mechanisms). It could be useful not only for scientific purposes but also as a concrete proof during the process of acquisition of the funding needed for upgrade and operation of the network. Moreover, the theoretical assessment can also identify the configuration where no improvement can be achieved with additional stations, establishing a tradeoff between the improvement and additional expenses. This paper presents suggestion of a combination of suitable methods and their application to the Little Carpathians local seismic network (Slovakia, Central Europe) monitoring epicentral zone important from the point of seismic hazard. Three configurations of the network are considered: 13 stations existing before 2011, 3 stations already added in 2011, and 7 new planned stations. Theoretical errors of the relative location are estimated by a new method, specifically developed in this paper. The resolvability of focal mechanisms determined by waveform inversion is analyzed by a recent approach based on 6D moment-tensor error ellipsoids. We consider potential seismic events situated anywhere in the studied region, thus enabling “mapping” of the expected errors. Results clearly demonstrate that the network extension remarkably decreases the errors, mainly in the planned 23-station configuration. The already made three-station extension of the network in 2011 allowed for a few real data examples. Free software made available by the authors enables similar application in any other existing or planned networks.
KeywordsSeismic network Relative location uncertainty Focal-mechanism uncertainty Waveform inversion Uncertainty mapping Weak earthquakes Little Carpathians
Lucia Fojtíková and Jiří Málek have been supported by the Czech Science Foundation grant GACR-P210/12/2336. Jiří Zahradník has been supported by the Czech Science Foundation grant GACR-14-04372S. Miriam Kristeková, Kristian Csicsay have been supported by the Slovak Foundation Grant VEGA-2/0188/15. Miriam Kristeková has been supported as well by the project: MYGDONEMOTION APVV-0271-11, funded by the Slovak grant agency APVV. The authors thank Progseis company for providing the data from their local seismic network and Jaroslav Štrunc for cooperation in the development of new stations. The authors also thank Antonio Emolo, Ronnie Quintero, and Lucas V. Barros for constructive comments.
- Fojtíková L (2010b) Earthquake moment tensors and tectonic stress in Malé Karpaty Doctoral thesis (in Slovak) http://www.fyzikazeme.sk/mainpage/prace/2010_PhD_Fojtikova.pdf
- Herrmann RB (1979) FASTHYPO—a hypocenter location program. Earthq Notes 50(2):25–37Google Scholar
- Kárník V (1968) Seismicity of the EuropeanArea. Part 1. Academia, PrahaGoogle Scholar
- McLaren JP, Frohlich C (1985) Model calculations of regional network locations for earthquakes in subduction zones. Bull Seismol Soc Am 75:397–413Google Scholar
- Press WH, Teukolsky SA, Vetterling WT, Flannery BP (1997) Numerical Recipes in Fortran 77: The Art of Scientific Computing, Second Ed., Cambridge University Press, 992 pages.Google Scholar
- Snoke JA (2003) FOCMEC: FOcal MEChanism determinations. In: Lee WHK, Kanamori H, Jennings PC, Kisslinger C (eds) International handbook of earthquake and engineering seismology. Academic Press, San Diego, Chapter 85.12Google Scholar
- Uhrhammer RA (1980) Analysis of small seismographic station networks. Bull Seismol Soc Am 70:1369–1379Google Scholar
- Zollo A, Iannaccone G, Lancieri M, Cantore L, Convertito V, Emolo A, Festa G, Gallovič F, Vassallo M, Martino C, Satriano C, Gasparini P (2009) The earthquake early warning system in Southern Italy: methodologies and performance evaluation. Geophys Res Lett 36:L00B07. doi: 10.1029/2008GL036689 CrossRefGoogle Scholar