**Author details**

initiative to supply volunteers with equipment to install and maintain a MSSstation, to perform their own data analysis aided by our computer programs, and to share "their" results with the community. We gladly support such initiatives.

The development of the MacroSeismic Sensor (MSS) in cooperation with teachers and students of the polytechnic TGM Wien was funded by the Federal Ministry of Education, Science and Research, Austria, the Austrian Academy of Sciences, and the Natural History Museum Vienna. Funds of the Federal State Government of Lower Austria allowed for the buildup of the MSS network in cooperation with teachers and students of the polytechnic HTBLuVA Wiener Neustadt. Additional sponsoring granted the Baumit GmbH (operator of a large quarry). Funding of the new MSS data visualizations is granted by netidee (https:// www.netidee.at/) for MSS Outreach. Map images in this publication have been

created using data from OpenStreetMap (www.openstreetmap.org, ©

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

OpenStreetMap-Contributors), OE3D (www.oe3d.at, © Rechenraum e.U.) and BEV (www.bev.gv.at, © BEV 2020). We express our thanks to mayors, officials, and private persons who supported the installation of the MSS stations in their communities. Furthermore we thank Wolfgang Lenhardt for critically reading and

We present the necessary formula to calculate the Apollonius circle centers und

ratio <sup>¼</sup> <sup>∣</sup>HI–P∣*=*∣LO–P<sup>∣</sup> <sup>¼</sup> ð Þ PGV\_HI*=*PGV\_LO <sup>1</sup>*=*<sup>n</sup>

P1 ¼ ð Þ HI þ ratio ∗ LO *=*ð Þ 1 þ ratio P2 ¼ ð Þ HI � ratio ∗ LO *=*ð Þ 1 � ratio

P1, P2...position vectors of possible source locations at the straight line

R = |P2 – P1| / 2...radius of the Apollonius circle or sphere C = (P1 + P2) / 2...center of the Apollonius circle or sphere

**Acknowledgements**

*Earthquakes - From Tectonics to Buildings*

commenting the manuscript.

From Eq. 1 follows:

Please note that n is negative.

connecting the HI and LO stations

radii. Please read [10] for a detailed description.

**Appendix**

**54**

Ewald Brückl<sup>1</sup> \*, Peter Carniel<sup>2</sup> , Stefan Mertl<sup>3</sup> and Rita Meurers<sup>4</sup>


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

© 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, provided the original work is properly cited.
