Tsunamis - the most deadly natural disaster - have been part of the world's history for thousands of years. Much of the world witnessed historical tsunamis that devastated the coast with great losses of life and property. Over the latter decade of the 20th century, the development of tsunami sciences has seen rapid growth as an interdisciplinary field that brings together scientists, engineers and researchers from all over the world. As a sequel to the first two editions - Tsunamis: Economic Impact, Disaster Management and Future Challenges in 2013 and Tsunamis: Detection, Risk Assessment and Crisis Management in 2018, the current edition of Tsunamis: Detection Technologies, Response Efforts and Harmful Effects serves as a collection of tsunami research that showcases on how the evolving technologies and innovative efforts in foreseeing the harmful effects of tsunamis. This current edition consists of five chapters authored by tsunami experts in their respective fields, from Malaysia, Indonesia, India, and Germany. These chapters are written with hopes of contributing towards continued progress in the future.