Science of Tsunami Hazards (Dec 2022)
THE 326 BC EARTHQUAKE AND TSUNAMI IN THE NORTHERN ARABIAN SEA - IMPACT ON THE FLEET OF ALEXANDER THE GREAT
Abstract
Ancient Greek and Indian texts support that destructive sea waves along the Makran coast in the northern Arabian Sea were responsible for the partial destruction of Alexander the Great’s fleet in 326 BC. At that time, and after the conclusion of all its operations along the Indus River and its tributaries, the Greek fleet had reached the Indian Ocean and was waiting in an estuary of River Hab, north of the Indus River delta, for calmer seas and for the seasonal monsoon winds to subside, before beginning the long journey from India to Babylon, in what is presently known as the Persian Gulf. Since the Greek fleet had spent considerable time in the fall of that year in protective bays of the Indus delta/Kutch and the Makran regions (India in ancient times), it is very possible that the reported sustained damage to the fleet was caused from a tsunami rather than storm waves. After repairs were completed, the fleet under the command of admiral Nearchus of Crete began its long and arduous journey west in the North Indian Ocean, towards Babylon in what is now known as city of Hillah of Iraq in the Persian Gulf. In all probability, the tsunami originated along the Makran Subduction Zone – the same source area that historically has produced several earthquakes and tsunamis, the best known in recent times being one in 1945. Based on reviews of ancient Greek accounts such as those of Plutarch, Nearchus but mainly of Arrian’s of Nicomedia “Indice” and to a lesser extent on Sri Lanka and Indian records, the present study reconstructed the chronology of the impact on the fleet based on the ancient Athenianlunar calendar. By using current geophysical knowledge of recent events in this region, and the present study concluded that the 326 BC earthquake occurred in late October or early November of 326 BC (known as Pyanepsion, “Πυανεψιών” in Ancient Greek). As mentioned, at that time the Greek fleet was either at anchor at the estuary near the delta of River Hab, or had just set out to sea on its way to Babylon. The Hab River estuary is located in the easternmost end of the Makran Subduction Zone (MSZ) in the Northern segment of the Arabian Sea - a source region of large earthquakes and tsunamis, recently and in the past. The delay in the departure of the Greek fleet from this estuary caused by opposing monsoon winds, limited the possibility of its total destruction if it had begun earlier its long journey to Babylon. Earlier in August of that same year, Alexander the Great with about a third of the Greek land forces had already taken a long and difficult march back to Babylon, via a southern land route, which included the harsh Gedrosian desert, a journey which resulted in the death from starvation for most of the soldiers. The present study is an evaluation of these events as deduced, from the historical records, but also from current geophysical understanding of the seism-tectonics of the Makran Subduction Zone - a source region of large earthquakes and tsunamis, recently and in the past. The best-known recent earthquake and tsunami in the same eastern region of the Makran Subduction Zone was the Moment Magnitude 8.1 earthquake of 19 November 1945.
