Loss of life and property from earthquakes is extensive and continues to grow in developing societies. On the other hand culture and social change have become key concepts in studies of mitigation of both natural and human-made disasters. The primary aim of this study is to demonstrate the impact of knowledge in terms of risk information on what people have thought and done to be prepared for the next probable earthquakes in both the USA and Turkey. In this cross-cultural comparative study, similar data to those from the Mileti's Bay Area study (1995) have been collected and analyzed. The present study revealed that for risks, knowledge alone is not sufficient and societal factors - along with the urgent need for cultural change in accordance with sustainable development - should be taken into consideration.