This is an Icelandic name. The last name is a patronymic, not a family name; this person is properly referred to by the given name Haraldur. However, since he is internationally active, Sigurdsson may also be correct.Haraldur Sigurðsson (born May 31, 1939) is an Icelandic volcanologist and geochemist. Sigurðsson studied geology and geochemistry in the United Kingdom, where he obtained a Bachelor's degree from Queen's University, Belfast, followed by a Ph.D.