Raphael S.M. De Plaen

Royal Observatory of Belgium · Section of Seismology

Archived seismograms recorded in the 20th century present a valuable source of information for monitoring earthquake activity. However, old data, which are only available as scanned paper-based images should be digitised and converted from raster to vector format prior to reuse for geophysical modelling. Seismograms have special characteristics and...

The raw seismic data is band-pass filtered between 1.0-2.0 Hz, down-sampled from 100 to 20 Hz, and de-trended. Daily traces is segmented into 1-hr windows, winsorizing (clipping) at 3 Root Mean Square (RMS), and spectral whitening in the 1.0–2.0 Hz frequency band is applied before cross-correlation (Bensen et al., 2007; Lecocq et al., 2014). The re...

Microseism is the continuous background seismic signal caused by the interaction between the atmosphere, the hydrosphere and the solid Earth. Several studies have dealt with the relationship between microseisms and the tropical cyclones, but none focused on the small-scale tropical cyclones that occur in the Mediterranean Sea, called Medicanes. In...

This work analyzes temporal variations of seismic velocities at Mt. Etna from August 2018 to February 2019. During this time period, a strong flank eruption accompanied by intense seismicity and ground deformation took place along a fracture that opened on 24 December 2018 at the base of the New South-East summit crater. Furthermore, two moderate e...

A large fraction of volcanic eruptions does not expel magma at the surface. Such an eruption occurred at Mt Ontake in 2014, claiming the life of at least 58 hikers in what became the worst volcanic disaster in Japan in almost a century. Tens of scientific studies attempted to identify a precursor and to unravel the processes at work but overall rem...

Before digital recordings became available in the 1970s, the ground motion was recorded using ink on white paper, scratching black-smoked paper, or light on photographic paper. While those analog seismic records offer unique continuous observations from the last century, most of them are now stacked and archived in boxes and potentially exposed to...

Volcán de Colima is one of the most active volcanoes in North America. Even so, it has a poorly constrained upper crustal structure. Here, we present the highest-resolution three-dimensional shear-wave velocity tomography to date of the volcano. We measured group velocity dispersion curves of Rayleigh and Love waves extracted from ambient seismic n...

Ambient noise seismic interferometry is a powerful tool to monitor the variations of seismic wave velocities due to volcanic and seismic activities. This work analyzes the temporal variations of seismic velocities at Mt. Etna from January 2018 to March 2019. During this time period, a violent eruption accompanied by intense seismicity and ground de...

The world experienced the beginning of the COVID-19 pandemic by the end of 2019 to the beginning of 2020. Governments implemented strategies to contain it, most based on lockdowns. Mexico was no exception. The lockdown was initiated in March 2020, and with it, a reduction in the seismic noise level was witnessed by the seismic stations of the natio...

Seismometers have detected the social response to lockdown measures implemented following the onset of the COVID-19 pandemic in cities around the world. This long-lasting pandemic has been a particular challenge in countries such as Mexico, where the informal economy constitutes most of the working population. This context motivated the monitoring...

During the COVID-19 pandemic, most countries put in place social interventions, restricting the mobility of citizens, to slow the spread of the epidemic. Italy, the first European country severely impacted by the COVID-19 outbreak, applied a sequence of progressive restrictions to reduce human mobility from the end of February to mid-March 2020. He...

The world experienced the beginning of the COVID-19 pandemic by the end of 2019, beginning of 2020. Governments implemented strategies to contain it, most based on lockdowns. Mexico was not the exception. The lockdown was initiated in March 2020 and with it, a reduction on the seismic noise level was witnessed by the seismic stations of the nationa...

Seismometers have detected the social response to lockdown measures implemented following the onset of the COVID-19 pandemic in cities around the world. This long-lasting lockdown has been a particular challenge in countries such as Mexico, where the informal economy constitutes most of the working population. This context motivated the monitoring...

During the COVID-19 pandemic, most countries worldwide put in place social interventions, consisting of restricting the mobility of citizens, aimed at slowing and mitigating the spread of the epidemic. In particular, Italy, as the first European country violently struck by the COVID-19 outbreak, applied a sequence of progressive restrictions to red...

Human activity causes vibrations that propagate into the ground as high-frequency seismic waves. Measures to mitigate the COVID-19 pandemic caused widespread changes in human activity, leading to a months-long reduction in seismic noise of up to 50%. The 2020 seismic noise quiet period is the longest and most prominent global anthropogenic seismic...

On active volcanoes, ambient noise-based seismic interferometry can be a very useful monitoring tool as it allows to detect very slight variations in seismic velocity associated with magma transported toward the surface. However, the classical cross-station approach occasionally fails to detect seismic velocity changes related to eruptive activity,...

In the framework of the regional EURAMET.M.G-K2 comparison of absolute gravimeters, 17 gravimeters were compared in November 2015. Four gravimeters were from different NMIs and DIs, they were used to link the regional comparison to the CCM.G.K2 by means of linking converter. Combined least-squares adjustments with weighted constraint was used to de...

Seismic ambient noise cross correlation is increasingly used to monitor volcanic activity. However, this method is usually limited to volcanoes equipped with large and dense networks of broadband stations. The single station approach may provide a powerful and reliable alternative to the classical “cross-stations” approach when measuring variation...

Release 1.4 of MSNoise, the Python Package for Monitoring Seismic Velocity Changes using Ambient Seismic Noise. Release Notes: http://msnoise.org/doc/releasenotes/msnoise-1.4.html Contributors: http://msnoise.org/doc/contributors.html

Abstract: The magmatic – hydrothermal system of Kawah Ijen volcano is one of the most exotic on Earth, featuring the largest acidic lake on the planet, a hyper-acidic river and a passively degassing silicic dome. While previous studies have mostly described this unique system from a geochemical perspective, to date there has been no comprehensive g...

In November 2013 an International Key Comparison, CCM.G-K2, was organized in the Underground Laboratory for Geodynamics in Walferdange. The comparison has assembled 25 participants coming from 19 countries and four different continents. The comparison was divided into two parts: the key comparison that included 10 NMIs or DIs, and the pilot study i...

The Cameroon Volcanic Line (CVL) straddles the continent-ocean boundary in west Africa, but exhibits no clear age progression. This renders it difficult to explain by traditional plume/plate-motion hypotheses; thus there remains no consensus on the processes responsible for its development. To understand better the nature of astheno-spheric flow be...

The Cameroon Volcanic Line (CVL) straddles the continent-ocean boundary in west Africa, but exhibits no clear age progression. This renders it difficult to explain by traditional plume/plate-motion hypotheses; thus there remains no consensus on the processes responsible for its development. To understand better the nature of asthenospheric flow ben...

The Cameroon geological record spans more than 3 billion years, from Congo Craton basement formation during the Archean, to Cenozoic volcanism along the Cameroon Volcanic Line (CVL). Intriguingly, the CVL, which straddles the continent-ocean boundary in central West Africa, displays no age-progression along its length. Analogies with other hotspot...