Abstract
A major left-lateral strike-slip Mw7.7 earthquake occurred in the vicinity of the Caribbean Sea on January 28, 2020. As a result, a small-scale tsunami was generated. The properties of the seismogenic source were described using observational data gathered for the earthquake and tsunami, as well as information on the regional tectonic setting. The tsunami was simulated with the COMCOT model and Okada’s dislocation model from finite fault solutions for MW7.7 Caribbean Sea earthquakes published by the United States Geological Survey. The simulation results were compared to tide gauge records to validate whether the seafloor’s vertical displacement generated by the strike-slip fault caused a small-scale tsunami. We conducted a spectral analysis of the tsunami to better understand the characteristics of tsunami records. The tsunami simulation results showed that the co-seismic vertical displacement caused by a strike-slip MW7.7 earthquake could have contributed to the small-scale tsunami, but the anomalously large high-frequency tsunami waves recorded by the George Town tide gauge 11 min after the earthquake were unrelated to the earthquake-generated tsunami. According to the spectrum analysis, the predominant period of noticeable high-frequency tsunami waves recorded by the George Town tide gauge occurred only two minutes after the earthquake. This indicates that the source of the small-scale tsunami was close to the George Town station and the possible tsunami source was 150 km away from George Town station. These facts suggest that a submarine landslide was caused by the strike-slip earthquake. The comprehensive analysis showed that the small-scale tsunami was not caused solely by co-seismic seafloor deformation from the strike-slip event but that an earthquake-triggered submarine landslide was the primary cause. Therefore, the combined impact of two sources led to the small-scale tsunami.
Highlights
At 19:10 on January 28, 2020 (UTC), a large earthquake measuring MW7.7 (Harvard CMT) struck the Caribbean Sea region (19.421° N, 78.763° W) between Jamaica, the Cayman Islands and Cuba, with a focal depth of 14.8 km
Tsunami simulation results show that the coseismic vertical displacement caused by a strike-slip MW7.7 earthquake can contribute to the small tsunami, and the anomalously large high-frequency tsunami waves recorded by the George tide gauge in 11 minutes after the earthquake were unrelated to the earthquake-generated tsunami
This indicates that the source of small tsunami was close to the George station and travelled a distance of ~ 150 km, indicating a submarine landslide caused by the strike-slip earthquake
Summary
At 19:10 on January 28, 2020 (UTC), a large earthquake measuring MW7.7 (Harvard CMT) struck the Caribbean Sea region (19.421° N, 78.763° W) between Jamaica, the Cayman Islands and Cuba, with a focal depth of 14.8 km. Historical tsunamis associated with major strike-slip earthquakes, such as the 1929 MW7.2 Grand Banks earthquake, the 1976 MW7.1 Mindanao, Philippine earthquake, the 1989 MW6.9 Loma Prieta earthquake, the 1994 MW7.1 Mindoro, Philippines earthquake, the 1999 MW7.4 Izmit, Turkey earthquake, the 2010 MW7.0 Haiti earthquake, and the 2018 MW7.5 Sulawesi, Indonesia earthquake had been observed resulting to destructive local tsunami (Hasegawa & Kanamori, 1987; Stewart & Cohn, 1979; Ma et al 1991; Imamura et al 1995; Altinok et al 2001; Hornbach et al 2010; Heidarzadeh et al 2019) This study provides a better understanding of tsunami-generated sources in the Caribbean Sea, and has important implications for the tsunami risk assessment in the Caribbean Sea and surrounding areas
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