A Tsunami Warning System based on Offshore Bottom Pressure Gauges and
Data Assimilation for Crete Island in the Eastern Mediterranean Basin
Abstract
The Eastern Mediterranean Basin (EMB) is under the threat of tsunami
events triggered by various causes including earthquakes and landslides.
We propose a deployment of Offshore Bottom Pressure Gauges (OBPGs)
around Crete Island, which would enable tsunami early warning by data
assimilation for disaster mitigation. Our OBPG network consists of 12
gauges distributed around Crete Island. The locations of OBPGs are
confirmed by Empirical Orthogonal Function (EOF) analysis of the
pre-calculated tsunami scenarios, and most of them are placed at the
locations where the most energetic wave dynamics occur. We demonstrate
three test cases comprising a hypothetical seismogenic tsunami in east
Sicily, a hypothetical landslide tsunami in the Aegean Sea, and the real
tsunami event of the May 2020 off the Crete earthquake. Our designed
OBPG network achieves a forecasting accuracy of 88.5 % for the
hypothetical seismogenic tsunami and 85.3% for the hypothetical
landslide tsunami with warning lead times of 10-20 min for both cases.
For the real event of May 2020, it predicts the tsunami arrival at tide
gauge NOA-04 accurately; the observed and forecasted amplitudes of the
first wave are 5.0 cm and 4.5 cm, respectively. The warning lead time
for the May 2020 event was ~10 min. Therefore, our
results reveal that the assimilation of OBPG data can satisfactorily
forecast the amplitudes and arrival times for tsunamis in the EMB. We
note that further studies are necessary to examine the relation between
the performance of the system and the number of OBPGs or the tsunami
characteristics.