000004849 001__ 4849
000004849 005__ 20241203103805.0
000004849 0247_ $$2DOI$$a10.1785/0220190276
000004849 037__ $$aSCART-2020-0101
000004849 100__ $$aLecocq, T.
000004849 245__ $$aOn the Extraction of Microseismic Ground Motion from Analog Seismograms for the Validation of Oceanic-Climatic Models
000004849 260__ $$c2020
000004849 520__ $$aWe report on a pilot demonstration of the usefulness of analog seismograms to improve the database of ocean storms before the 1980s by providing additional data for the quantitative validation of ocean wave modeling, in particular for extreme events. We present a method for automatic digitization of paper seismograms to extract microseismic ground‐motion periods and amplitudes. Each minute of the original paper records is scanned and vectorized. The amplitudes are calibrated based on the original metadata taken from official bulletins. The digitized time series is processed to extract power spectral densities, which are compared with modeled microseisms levels computed using a numerical ocean wave model. As a case study, we focus on one month of data recorded at the Royal Observatory of Belgium (ROB) from January to February 1953, around the “Big Flood” event, a tragic storm surge that flooded the lowlands of England, the Netherlands, and Belgium on 1 February 1953. The reconstructed spectrograms for the three components of ground motion show clear storm signatures that we relate to specific sources in the North Atlantic Ocean. However, our models of the Big Flood event based on these data do not result in the expected amplitudes as modeled compared to the observational data when the storm reached its maximum in the southern North Sea. We suggest that the source of microseisms recorded at ROB is related to the primary microseism generated in the North Sea, at periods of 7–8 s. Other discrepancies identified suggest small modifications of the source locations or energy. Reconstructed horizontal and vertical ground motions are coherent. This is a good news for the purpose of present‐day analyses of constructing twentieth century ocean‐climate models, especially as during much of that time only horizontal seismographs were installed at observatories.
000004849 594__ $$aNO
000004849 700__ $$aArdhuin, F.
000004849 700__ $$aCollin, F.
000004849 700__ $$aCamelbeeck, T.
000004849 773__ $$pSeismological Research Letters$$y2020
000004849 8560_ $$fthomas.lecocq@observatoire.be
000004849 85642 $$ahttps://github.com/ThomasLecocq/SRL_2020_Historical
000004849 8564_ $$s1706908$$uhttps://publi2-as.oma.be/record/4849/files/0220190276fig3.png$$y15 January–15 February 1953 displacement power spectral density (PSD) spectrograms based on the automatically extracted time series for the (a) vertical, (b) east–west, (c) north–south components, and (d) the result of the modeling using WAVEWATCH III and coastal reflections (REF102040). The thin white contours that highlight the   and   levels are indicated for illustration purposes only. The thick dashed white line indicates the time of occurrence of the Big Flood. The arrows indicate the five periods of significant microseismic activity; labeled E1–E5 in the Microseismic Activity in January–February 1953 section and the following figures.
000004849 8564_ $$s15120$$uhttps://publi2-as.oma.be/record/4849/files/0220190276fig3.jpg?subformat=icon-180$$xicon-180$$y15 January–15 February 1953 displacement power spectral density (PSD) spectrograms based on the automatically extracted time series for the (a) vertical, (b) east–west, (c) north–south components, and (d) the result of the modeling using WAVEWATCH III and coastal reflections (REF102040). The thin white contours that highlight the   and   levels are indicated for illustration purposes only. The thick dashed white line indicates the time of occurrence of the Big Flood. The arrows indicate the five periods of significant microseismic activity; labeled E1–E5 in the Microseismic Activity in January–February 1953 section and the following figures.
000004849 8564_ $$s18998$$uhttps://publi2-as.oma.be/record/4849/files/0220190276fig3.gif?subformat=icon$$xicon$$y15 January–15 February 1953 displacement power spectral density (PSD) spectrograms based on the automatically extracted time series for the (a) vertical, (b) east–west, (c) north–south components, and (d) the result of the modeling using WAVEWATCH III and coastal reflections (REF102040). The thin white contours that highlight the   and   levels are indicated for illustration purposes only. The thick dashed white line indicates the time of occurrence of the Big Flood. The arrows indicate the five periods of significant microseismic activity; labeled E1–E5 in the Microseismic Activity in January–February 1953 section and the following figures.
000004849 905__ $$apublished in
000004849 980__ $$aREFERD