Inaugural Lecture – Significance of Terrestrial Impact Structures: A Case Study of the Lake Bosumtwi Impact Crater, Ghana – Prof Sylvester Danuor_22 June 2023

The main aim of the Inaugural Lecture is to educate and inform the general public about the importance of Planetary Sciences and the existence of planetary objects that can hit the Earth with catastrophic environmental consequences; a clear example is the Lake Bosumtwi crater near Kumasi, which was formed by the impact of a meteorite about 1 million years ago.

The crater has a diameter of 10.5 km and is occupied by the 8 km diameter Lake Bosumtwi, which has a maximum depth of 75 m. It is located in the Bosumtwi District of the Ashanti Region. It is now an established fact that a meteorite impact caused the extinction of the dinosaurs and other species about 65 million years ago, popularly known as the Cretaceous-Tertiary (or K/T) boundary event. Meteorite impacts are, therefore, possible destroyers of civilization. For the Bosumtwi meteorite, it has been estimated that the energy released during the impact is several thousand times bigger than the Hiroshima atomic bomb. One can therefore imagine the environmental consequences at the time. The formation process of impact craters gives rise to scientific questions that need to be answered to confirm an impact origin for the crater and obtain information on its deeper structure. The impact leads to changes in the physical and lithological properties of the rocks by the shock waves, and the very high pressures and temperatures generated. The Lecture will therefore dwell on the geophysical investigations that have been carried out to determine the subsurface structure of the crater, the impact process and the tectonic disturbance of the area which poses some environmental concerns.

Further, the Lecture will present the criteria for the identification and confirmation of impact structures including the geophysical characteristics or anomalies. The Lecture will also touch on the economic potential of impact craters, the scientific importance of the Bosumtwi impact crater and the promotion of its immense educational and eco-tourism potential. Lake Bosomtwe has been designated by UNESCO as a World Heritage Site. It has also been recognised by the international scientific community as a World Geological Site. Lake Bosomtwe is a unique meteorite crater heritage site in West Africa. It has therefore been proposed to establish a Meteorite Crater and Cultural Heritage Centre at the site.

In conclusion, it will be emphasized that understanding impact structures, their formation processes, and their consequences should be of interest not only to earth and planetary scientists but also to society in general. The biological evolution of planets is punctuated by mass extinction events, the well-known one being the impact event 65 million years ago at the Cretaceous-Tertiary boundary. Attempts will be made to answer questions such as “When do we expect a large impact that may disrupt our civilization?” and “How can we reduce the impact hazard?”