Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

The 30 October 2020 Samos Island, Greece Earthquake: Focal Mechanism of the Mainshock andTsunami Simulation
Zhiguo Xu, Zongchen Wang, Jianyu Shi, Hongwei Li
National Marine Environmental Forecasting Center, Ministry of Natural Resources.
Beijing, China

Papadimitriou et al. 2020). The distance between the USGS’s initial
epicenter and GCMT’s centroid location is ~19 km (Fig. 1), indicating
the the seismogenic zone is not considered to be single point source, themain rupture slip is located to west of the epicenter. The two major slip
patches derived from the regional finite fault modeling. Hence, weemployed the multiple-point source modeling to explore the focal
mechanism characteristics, and further unveiling the temporal andspatial characteristics of the rupture.
The coseismic deformation observation showing obvious subsidence atthe northern part of Samos Island and mainly uplift on western part(Sakkas, 2021). The large earthquake dislocation caused by normal
faulting movement might be the main cause of tsunami generation.
Therefore, the preliminary simulation of tsunami from Samos MW7.0
earthquake was carried out to detail describe its generation andpropagation, and to promote understanding and predicting future
tsunamis in this region.

ABSTRACTMultiple-point source solution of 2020 Samos MW7.0 earthquake inGreek was inverted using iterative deconvolution method from nearfield seismic records. The retrieving results have revealed that SamosMW7.0 earthquake consisted of at least two subevent with similar
normal fault-typing, the smaller subevent corresponds to ~3 s rupture
time close to mainshock epicenter, the larger one has its position
approximately 25 km west of the original rupture point with 8 s later
moment release. We inferred that Samos earthquake occurred on anormal fault along the nearly EW trending, and two subevents
successively ruptured separated by ~5 s. Furthermore, numericalsimulation of the tsunami generated by Samos normal faulting
earthquake was conducted from the uniform slip source model,
indicating the Samos earthquake occurred as subsidence of normal fault
hanging wall, and led to a large sudden coseismic vertical deformation
surrounding the focal region, thus displacing the overlying water andproduced a small scale local tsunami.

KEY WORDS: Samos earthquake; Focal mechanism; Normal
faulting earthquake; Tsunami

INTRODUCTION
A massive MW = 7.0 earthquake that occurred ~10 km to the north andoffshore of Samos Island, Greece (37.897°N 26.784°E) On 30 October
2020 11:51 UTC, at a shallow depth of ~21 km. This earthquake caused
extensive damage on its surrounding areas, resulted in the collapse ofbuildings, numerous fatalities, and missing people, at least ~117 people
were killed by earthquake. Most notably, the mainshock also triggereda powerful local tsunami that flooded into the island of Samos Island,
Greece and the Aegean coast of the Izmir region, Turkey, and caused
severely damage to building and structure, one person killed bydrowning.
After the Samos mainshock, the researchers from various earthquake
agencies have made great progresses in understand this earthquake. The
analysis of the mainshock and aftershock sequence reveals that it
occurred on a nearly EW striking dip-slip normal fault located off thenorthern shore of Samos Island (Onder-Cetin et al., 2020;

Fig. 1. The epicenter of Samos MW7.0 earthquake and mapping ofmajor faults in the Samos Island and surrounding areas.

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