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Poster De Conférence Année : 2021

Influence of the ambient noise level of Raspberry Shake seismographs on the performance of the Ayiti-séismes platform

Sylvert Paul
Tony Monfret
Françoise Courboulex
Eric Calais
  • Fonction : Auteur
  • PersonId : 1083512
Sadrac St Fleur
  • Fonction : Auteur
Steeve Julien Symithe
  • Fonction : Auteur
Anne Deschamps
Jérôme Chèze
Fabrice Peix

Résumé

The development of low-cost Raspberry Shake (RS) seismological stations capable of providing scientifically relevant seismological information in near-real time has enabled a Haitian citizen network to be set up as part of a participatory seismology experiment that Started in July 2019. This network currently operates 12 RS instruments. These are associated with broadband stations (BB) of the Bureau of Mines and Energy of Haiti (BME) and the Canadian National Seismograph Network (CNSN) for the continuous monitoring of seismicity in Haiti. All these stations are combined with other stations in the region for the detection and automatic location of earthquakes in Haiti, with an open broadcast from the Ayiti-Séismes (https://ayiti.unice.fr/ayiti-seismes/) platform. While the BB sensors are placed in relatively quiet places and benefit from a professional installation, the RS stations are placed in private homes, sometimes in their living room or garden. Due to the variability of the quality of their internet communication and power, the percentage of available RS recordings varies considerably from one site to another. Moreover, these recordings are only available in a reduced range of frequencies and are a priori of lower quality, as they are attenuated by local ambient noise. We propose here to quantify the effect of this noise and the impact of the environment on the quality of the recorded seismic signals. To do so, we analyzed a set of data sets, from a period of one month with a minimum availability of 84.8%, from ten RS and one SDDR broadband station located in the Dominican Republic. To quantify the noise, we estimate the Power Spectral Density (PSD) of the noise at 1/8 octave bands that we accumulate in 1 dB bands. Then, we perform a static analysis of the set of PSD curves computed at each of the study stations to present the final result as a probability density function (PDF). For the final evaluation of the ambient noise variation around each station, we retain the highest probability noise level which is the statistical mode of the noise levels from the PDFs. The results thus obtained show overall that the environment of the stations is very noisy. However, RS R50D4, located 21 km from the epicenter of the August 14, 2021 earthquake, has an acceptable noise level compared to the SDDR station, taken as the reference station in this study. Based on the appreciable noise level of this station, we conclude that a favorable path to detect and locate low magnitude and ultimately decrease the magnitude of completeness would be to multiply the RS while following the installation protocol of R50D4. Despite a high ambient noise level for the majority of RS stations, a large number of seismic events could be detected and located in Haiti and near its borders. In the near future, we plan to install 30 additional RS stations in Haiti to improve the detection and characterization of events of magnitude lower than 2.5.
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Dates et versions

hal-03538773 , version 1 (21-01-2022)

Identifiants

  • HAL Id : hal-03538773 , version 1

Citer

Sylvert Paul, Tony Monfret, Françoise Courboulex, Eric Calais, Sadrac St Fleur, et al.. Influence of the ambient noise level of Raspberry Shake seismographs on the performance of the Ayiti-séismes platform. American Geophysical Union, AGU Fall Meeting, Dec 2021, New Orleans, United States. pp.S25E-0293. ⟨hal-03538773⟩
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