On November 16, 2020, an outstanding Russian seismologist Aleksey Illarionovich Ivashchenko passed away from the severe form of COVID-19. For 40 years of work on Sakhalin, he rose from an engineer to the head of the Seismology Laboratory and Scientific Deputy Director of the IMGG FEB RAS. A.I. Ivashchenko worked for 14 years at the Tsunami Laboratory named after the academician S.L. Soloviev at the IO RAS, Moscow. His contribution to the study of earthquakes and, in particular, tsunamigenic earthquakes, the types of their sources and the assessment of the risk of these events is invaluable. A.I. Ivashchenko was an exceptionally competent and responsible scientist, a very experienced and intelligent leader, an excellent and benevolent teacher and tutor of young people, and a reliable friend.