Underground radon gas concentrations related to earth tides

Over several years, radon concentrations have been recorded in a former gypsum mine near Walferdange (Luxembourg). Because of the exceptional quality of the site (thermal stability better than 0.01 7C/year, no running water, easy access, far enough from the oceans), today the mine hosts an underground laboratory for geodynamics and seismology with more than 25 permanent instruments that continuously record earth tides, earth quakes and meteorological parameters. One of the main interests in monitoring radon concentrations in this mine was to check the ability of earth tide effects on radon concentrations in the mine atmosphere. First results show that besides outside temperature and atmospheric air pressure, radon concentrations seem to be influenced by earth tides. Power spectra, calculated for different time series of radon concentrations, show the presence of both O1 (lunar declination) and M2 (principal lunar) tides. The increase in vertical extension and the decrease in gravity induced by earth tides in the bulk of the rocks may open supplementary pathways for radon and thus induce an increase of the radon transport through the rocks

Global Monitoring of Volcanic SO2 Degassing Using Sentinel-5 Precursor Tropomi

We present here the TROPOMI SO 2 product, which is publicly available since April 2018. We describe the capabilities and limitations of the product for the monitoring of volcanic SO 2 degassing. With several examples, we illustrate the benefit of a small satellite pixel of 3.5 x 5.5 km 2 . Owing to its improved detection limit, the data can be used to generate time series of SO 2 mass over number of volcanoes, with a large range of SO 2 emissions. We use Nyiragongo as a show case and correlate the SO 2 mass data with lava lake level estimates and local measurements of the seismicity. This paper also presents on-going developments to further improve the performance of the product for weak SO 2 loadings using a new algorithm, COBRA

About Time Variations of Gravity

Advances in gravity instrumentation have allowed for the determination of the absolute acceleration of gravity to a precision of 3–5 μGal and observations of tidally driven changes in gravity on the order of nanogals. With observations of gravity and changes in gravity at these levels of precision we are able to investigate problems such as the resonance of the Earth's liquid inner core, to discriminate between the various ocean tidal models, understand the effects of atmospheric pressure loading on gravity observations, and perhaps to measure ice mass changes in Greenland. In this paper, we report on some of our results using absolute and superconducting gravimeter data. We describe a project to establish a site for international comparisons of absolute gravimeters in Luxembourg

Identification of subsiding areas undergoing significant magmatic carbon dioxide degassing, along the northern shore of Lake Kivu, East African Rift

We processed InSAR time series of ENVISAT ASAR descending and ascending datasets and identified two new deforming areas on the northern shore of Lake Kivu, characterized by steady ground subsidence of up to ~1 cm/year over a time period of about seven years (December 2002/January 2003–March 2010). Two distinct areas can be identified: one centered on the Rumoka volcanic cone, which built up during the 1912 eruption of Nyamulagira volcano, and a broader one centered on the Bulengo area on the northern shoreline of Lake Kivu. Both areas include high density of diffuse magmatic degassing areas (“mazuku”), which are topographic depressions in which substantial amount of carbon dioxide accumulates. The steady deflation of at least two fluid reservoirs is consistent with geodetic data but the presence of weak, porous layers, possibly connected with hydrothermal and hydrogeological processes in aquifers and Lake Kivu, could also account for the observed subsidence. The subsidence could be due to pore pressure decrease in porous layers, which may also serve as preferential pathways for escaping gases percolating from the aquifers and Lake Kivu

MASTER: A FULL AUTOMATIC MULTI-SATELLITE INSAR MASS PROCESSING TOOL FOR RAPID INCREMENTAL 2D GROUND DEFORMATION TIME SERIES

peer reviewedTaking advantage of the ever-increasing amount of available SAR data requires adapted processing infrastructures. We present here the InSAR Mass processing Toolbox for Multidimensional time series (MasTer), which can combine any type of SAR data to produce unsupervised vertical and horizontal ground deformation time series. MasTer is optimized to automatically download SAR data, select the appropriate interferometric pairs, perform the interferometric mass processing, compute the geocoded deformation maps, invert and display the velocity maps and the 2D time series on a web page updated incrementally as soon as a new image is made available. MasTer also allows the production of time series of coherences or SAR amplitude images, which can be used e.g. for land use monitoring or geomorphological changes detection. The capabilities and performances of MasTer are illustrated with several examples. Software and manual are available on request to authors. To MasTer the art of InSAR mass processing

Comparative study of the tidal gravity parameters observed in Timanfaya, Jameos del agua and Cueva de los Verdes stations at Lanzarote island

The Island of Lanzarote, and the Canarian Archipielago, placed near the western African coast of Moroco has a volcanic origin, like all Canary Islands. The last eruptions in the island have taken place in the: XVII and XIX centuries. A very important eruption has ocufred between 1730 and 1736. which is one of the most prolonged volcanic manifestarion that we have information about. It has caused important cbanges in the topography of the island, affecting almost 25% of its surface. As a consequence of this eruption, Possibly due to a remaining superficial magma, there is a zone of strong geotermic anomalies. Thus, in the National Volcanic Park of Timanfaya can be measured now temperatures of 6O0º C order, only a few meters depht. Island's crust determined by gravity investigations as well as through seismic profiles, it is of 14 km order. Since 1987, the collaboration between the IAG (the Institute of Astronomy and Geodesy) and the Royal Ohservatory of Belgium (ROB) allows gravity tides observations in three different points of the island. Two of them, Cueva de los Verdes y Jameos del Agua, at the norther part. The third one it is placed at the Park of Timanfaya, just over the anomalies mentioned above. In the present paper we deal with the results which can be related with the crustal structure, geotermic anomalies, ocean effects, etc.Peer reviewe