# Satellite Measured Ionospheric Magnetic Field Variations over Natural Hazards Sites
## 5 Results
### Volcanoes  
Volcanic explosions and effusions, in particular Plinian eruptions with ejections of ashes into stratospheric heights, have the potential to devastate the surrounding community and local environment, significantly disturb and alter the atmosphere for longer time spans, in specific cases even years, with a marked global temperature decrease and a shift of weather pattern. Here, we consider immediate influences in close temporal proximity to reported and impending volcanic activities and investigate magnetic field variations at LEO altitudes in a spatial box of a few degrees in latitude and longitude around the volcano location. In addition, seismic activity prior to the eruption often relates to such cataclysmic processes. [PERSON] et al. (2016) [26] and [PERSON] et al. (2006) [27] reported ionospheric variations, with regard to volcanoes, based on total electron content (TEC) ground observations, [28] made a survey via measurements of the DEMETER microsatellite, and both [29; 30] investigated case studies with the CSES HPM magnetic field package. Such conceptions and considerations can be extended beyond the Earth to the solar system [31]. Bar@arbunga Caldera Collapse and Effusive Eruptions  
Bar@arbunga is one of Iceland's most active subglacial (under the Vatnajokull glacier) basaltic volcanoes. A specific event series--interconnected with magnitude M > 5 earthquakes and caldera collapse--lasted approximately 6 month, beginning from August 2014 with a seismic swarm to the end of seismic activity in February 2015. The massive lava fissure eruptions in the Huluraun plain started on 31 August 2014, and were accompanied by huge blasts of SO\({}_{2}\) gas [32]. The geodynamic setting consists not only of a volcanic eruption and caldera collapse event, but is associated with high seismicity and caldera earthquakes over a prolonged period, hence a series of complex intertwined sequences. As a case study, _Swarm_ A/B/C satellite magnetic field measurements are used to investigate these processes in a narrow confining spatial range with a box size of only \(\pm\)1.5 deg in geographical lat/long around Baroarbunga's location, and an extended time period of \(\pm\)10 days centred around 28 August 2014. This time span is also split in a geomagnetic quiet period up to 26 August 2014 (except 19 August 2014), and, thereafter, a disturbed period \begin{table}
\begin{tabular}{c c c c} \hline
**No.** & **Category** & **Event, Object** & **Satellite and Instrument** \\ \hline
1 & Volcano & Baroarbunga, Iceland & _Swarm_ A/B/C VFM \\
2 & Earthquake & Severo-Kurilsk, Russia, M6.5 & CSES HPM (FGM1) and _Swarm_ A/B/C VFM \\
3 & & Rio Caribe, Venezuela, M7.3 & CSES HPM (FGM1 and CDSM) \\
4 & & Ndoi Island, Fiji, M8.2 & CSES HPM (FGM1 and CDSM) \\
5 & & Ridgecrest, USA, M7.1 & CSES HPM (FGM1 and CDSM) \\
6 & Explosion & Baumgarten, Austria & _Swarm_ A VFM \\
7 & & Thahuelipan, Mexico & CSES HPM (FGM1 and CDSM) \\
8 & Rocket Launch & Falcon 9, SpaceX & _Swarm_ A/B/C VFM \\
9 & & Ariane 5, Arianespace, ESA & _Swarm_ A/B/C VFM \\ \hline \end{tabular}
\end{table} 
Table 1: Investigated lithospheric and (near) ground surface events with space based magnetic field measurements from CSES and _Swarm_ satellites at LEO altitudes. caused by a geomagnetic storm. All pre-event box crossings are under quiet conditions, i.e., these segments can serve as a low disturbed baseline for post-event crossings. Basically during the magnetic storm phases external influences can have adverse effects, including unwanted spurious signals which interfere with AGW induced variations.