When the Acquisition Conditions and Processing Procedures of Seismic Data Increase the Ground Motion Model Uncertainties: Example of the Impact of Obspy and of the Sensor Installation Choices
Description:
Understanding and reducing the epistemic uncertainties in earthquake ground motions models is currently one of the main challenges in probabilistic seismic hazard assessment. It is generally done by improving the earthquake source models, the seismic wave propagation representation or by relaxing the ergodic assumption by accounting for site effect. The quality of the data acquisition condition and the data processing are generally not questioned. The data-driven ground motion models implicitly assume that the ground motion used to derive the models have been measured at the free surface of the earth, that the sensor installation conditions and the seasonal effects can be neglected, and that open access instrumental correction tools such as Obspy can be used blindly.
In practice, many seismic stations are posthole station or are installed in tunnel. The soil-structure interaction effects of the station are generally underestimated. The existence of very short wavelength topographic features (such as scarps of a few meters in height) should also be considered. In some cases, seasonal variations in soil moisture can make the site response variable over time. We show here some examples of effects that have been observed on the stations of the French RESIF network and on temporary arrays deployed on the island of Cephalonia (Greece). These effects can lead to de-amplifications of a factor more than 10 at certain frequencies (in the case of deep stations) or to amplifications of the same order of magnitude (in the case of sensors on pillar). We also present an issue on the way the instrumental correction is performed on Obspy. The main objective here is to inform the ground motion modeler on the potential impact of these effects. The next step will be to quantify the epistemic uncertainties related to the acquisition and processing of the seismic data.
Session: Understanding and Modeling the Uncertainties in Earthquake Ground Motions [Poster]
Type: Poster
Date: 4/20/2023
Presentation Time: 08:00 AM (local time)
Presenting Author: Vincent Perron
Student Presenter: No
Invited Presentation:
Authors
Pauline Rischette pauline.rischette@cea.fr Atomic Energy and Alternative Energies Commission, centre d'étude de Cadarache |
Fabrice Hollender fabrice.hollender@cea.fr Atomic Energy and Alternative Energies Commission, centre d'étude de Cadarache, University Grenoble Alpes, ISTerre |
Vincent Perron Presenting Author Corresponding Author vincent.perron@cea.fr Atomic Energy and Alternative Energies Commission, centre d'étude de Cadarache |
Margaux Buscetti margaux.buscetti@cea.fr Atomic Energy and Alternative Energies Commission, centre d'étude de Cadarache |
|
|
|
|
|
When the Acquisition Conditions and Processing Procedures of Seismic Data Increase the Ground Motion Model Uncertainties: Example of the Impact of Obspy and of the Sensor Installation Choices
Category
Understanding and Modeling the Uncertainties in Earthquake Ground Motions