He is considered a pioneer in the field of tephrochronology, and he made significant contributions in many areas of geology, especially volcanology and glaciology, both in Iceland and abroad.

According to his obituary in The Geographical Journal, "He was something of a polymath who contrived to take geology, geomorphology, glaciology, climatology, and archaeology in his stride."

Subsequently, the International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) decided to name its highest award the Thorarinsson Medal in his honor.

Eldur er í Norðri is a collection of papers, published by his colleague when Sigurður turned 70 years old.

[3] He was the first to receive the award of Steno Medal in 1969 by the Geological Society of Denmark for his work with volcanology and tephrochronology.