Potential deployment of offshore bottom pressure gauges and adoption of data assimilation for tsunami warning system in the western Mediterranean Sea

Abstract

Western Mediterranean Basin (WMB) is among tsunamigenic zones with numerous historical records of tsunami damage and deaths. Most recently, a moderate tsunami on 21 May 2003 offshore Algeria, North Africa, was a fresh call for strengthening tsunami warning capabilities in this enclosed water basin. Here, we propose to deploy offshore bottom pressure gauges (OBPGs) and to adopt the framework of a tsunami data assimilation (TDA) approach for providing timely tsunami forecasts. We demonstrate the potential enhancement of the tsunami warning system through the case study of the 2003 Algeria tsunami. Four scenarios of OBPG arrangements involving 10, 5, 3 and 2 gauges are considered. The offshore gauges are located at distances of 120-300 km from the North African coast. The warning lead times are 20, 30, 48 and 55 min for four points of interest considered in this study: Ibiza, Palma, Sant Antoni and Barcelona, respectively. The forecast accuracies are in the range of 69-85% for the four OBPG scenarios revealing acceptable accuracies for tsunami warnings. We conclude that installation of OBPGs in the WMB can be helpful for providing successful and timely tsunami forecasts. We note that the OBPG scenarios proposed in this study are applicable only for the case of the 2003 Algeria tsunami. Further studies including sensitivity analyses (e.g., number of OBPG stations; earthquake magnitude, strike, epicenter) are required in order to determine OBPG arrangements that could be useful for various earthquake scenarios in the WMB.

Long Tsunami Oscillations Following the 30 October 2020 Mw 7.0 Aegean Sea Earthquake: Observations and Modelling

“…For Greece, the maximum runup was 3.4 m, measured on the north coast of Samos Island (Triantafyllou et al, 2021). The October 2020 tsunami was an important event and gained high media attention as it was a fresh call for strengthening tsunami preparation, mitigation, and awareness in the highly seismic zone of the Eastern Mediterranean and the Aegean Sea regions (Heidarzadeh & Gusman, 2021;Heidarzadeh et al, 2017Heidarzadeh et al, , 2019Ozel et al, 2011;Papadopoulos et al, 2020;Triantafyllou et al, 2021).…”

Probabilistic tsunami forecasting for early warning

“…For sufficiently distant earthquakes, tsunami forecasts can be constrained with moment tensors 5 , yet these forecasts are still characterized by significant uncertainty. Deep-sea sensors, where available, can further help constraining the tsunami through inversion and data assimilation techniques 4,[6][7][8][9][10] . However, locally, the tsunami may inundate after minutes 11 and initial tsunami forecast must be performed solely from basic earthquake parameters.…”

Toward Near‐Field Tsunami Forecasting Along the Cascadia Subduction Zone Using Rapid GNSS Source Models

“…However, it is important to note that for larger events as are tested here, the typical range for GNSS noise (between 2 and 5 cm) is much lower than the expected signal (Melgar et al, 2020). In addition to traditional on‐land GNSS, fully submarine data sets, such as pressure data from cabled networks, can provide key real‐time and direct tsunami information for earthquakes (Gusman et al, 2014; Heidarzadeh et al, 2019; Howe et al, 2019; Kanazawa et al, 2016; Maeda et al, 2015). This data can then be incorporated into geodetic and seismic assessments, providing high‐resolution models from trench to coastline, reducing some of the uncertainties common with geodetic models and highlighted above (Tsushima et al, 2014).…”