**Appendix**

We present the necessary formula to calculate the Apollonius circle centers und radii. Please read [10] for a detailed description.

HI, LO...position vectors of the higher and lower PGV station PGV\_HI, PGV\_LO...PGV/SA at the HI and LO stations P...position vector of unknown source locations From Eq. 1 follows:

$$\text{ratio} = |\text{HI-P}|/|\text{LO-P}| = (\text{PGV\\_HI/PGV\\_LO})^{1/n}$$

**Author details**

2 Private, Vienna, Austria

\*, Peter Carniel<sup>2</sup>

3 Mertl Research GmbH, Vienna, Austria

provided the original work is properly cited.

1 Technische Universität Wien, Vienna, Austria

4 Zentralanstalt für Meteorologie und Geodynamik, Vienna, Austria

*Seismological Data Acquisition and Analysis within the Scope of Citizen Science*

*DOI: http://dx.doi.org/10.5772/intechopen.95273*

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

\*Address all correspondence to: ewald.brueckl@geo.tuwien.ac.at

, Stefan Mertl<sup>3</sup> and Rita Meurers<sup>4</sup>

Ewald Brückl<sup>1</sup>

**55**

Please note that n is negative.

$$\mathbf{P1} = (\mathbf{HI} + \mathbf{ratio} \* \mathbf{LO})/(\mathbf{1} + \mathbf{ratio})$$

$$\mathbf{P2} = (\mathbf{HI} - \mathbf{ratio} \* \mathbf{LO})/(\mathbf{1} - \mathbf{ratio})$$

P1, P2...position vectors of possible source locations at the straight line connecting the HI and LO stations

R = |P2 – P1| / 2...radius of the Apollonius circle or sphere C = (P1 + P2) / 2...center of the Apollonius circle or sphere *Seismological Data Acquisition and Analysis within the Scope of Citizen Science DOI: http://dx.doi.org/10.5772/intechopen.95273*
