Passive Acoustic Monitoring: A New Tool in Marine Archaeology
Marine archaeology, the study of underwater cultural heritage like shipwrecks and ancient submerged settlements, has traditionally relied on visual surveys and physical exploration. However, with advancements in technology, a new tool is making waves in this field — Passive Acoustic Monitoring (PAM).
How Does PAM Work in Archaeology?
PAM is a method of listening to and recording the sounds in the ocean to monitor marine life and environmental conditions. This technology involves underwater microphones, known as hydrophones, that capture the natural and human-made sounds beneath the sea. While PAM has been primarily used for studying marine mammals like whales and dolphins, its application is expanding into the field of archaeology.
Underwater archaeological sites, such as shipwrecks or ancient coastal settlements, are often fragile and difficult to locate. Traditional methods can be invasive, sometimes disturbing the very sites researchers aim to protect. PAM offers a non-invasive alternative. By capturing the sounds of the ocean floor, PAM can help identify areas where artifacts or structures may be located without the need for direct contact.
For instance, the sounds of water moving through shipwrecks or over submerged structures can be distinct. These acoustic signatures can help researchers map the seabed and locate potential archaeological sites. Additionally, PAM can be used to monitor these sites over time, ensuring they are not disturbed by natural events or human activities like offshore drilling.
How PAM Helps Discover and Explore Cultural Heritage
PAM has been used to detect the presence of shipwrecks and submerged archaeological sites by monitoring the unique acoustic signatures these structures emit or reflect. Researchers can successfully identify historical shipwrecks by analyzing the acoustic reflections and sounds generated by currents moving around these submerged objects. For instance, in the eastern Mediterranean, PAM has helped archaeologists locate and study the remains of ancient warships, providing insights into historical naval strategies and shipbuilding techniques.
Here are just a few interesting examples of ancient warships that have been discovered and studied with the help of PAM.
The Antikythera Shipwreck
Discovered off the coast of Antikythera, Greece, this ancient shipwreck dates to around 60-50 BC. It is famous for the Antikythera mechanism, an ancient analog computer used to predict astronomical positions and eclipses. PAM has helped locate and map the remains of this ship, providing insights into ancient Greek naval technology and trade routes.
The Battle of Actium Wrecks
The Battle of Actium (31 BCE) was a decisive naval battle between Octavian and Mark Antony. Several shipwrecks associated with this battle have been discovered, and PAM has played a role in locating these wrecks and studying the remains of Roman warships, shedding light on Roman naval strategies and shipbuilding techniques.
The Uluburun Shipwreck
This Bronze Age shipwreck was discovered off the coast of Uluburun, Turkey, and dates back to around 1300 BC. The shipwreck has provided valuable information about ancient trade networks and maritime technology. PAM has been used to survey and study the remains of this ship and its cargo.
The Kyrenia Shipwreck
Discovered off the coast of Cyprus, this Greek merchant ship dates to around 300-250 BC. While not a warship, its study through PAM has contributed to understanding ancient maritime practices and the construction of ancient ships.
How PAM Helps Protect Underwater Archaeological Sites
PAM technology can help protect underwater archaeological sites from illegal activities, such as looting or unauthorized diving. By detecting the sounds of boat engines or diving equipment, authorities can intervene promptly to prevent damage to these valuable sites.
Before initiating underwater excavations, PAM can assess the impact of such activities on the surrounding marine environment. This is crucial in preserving not only the local marine life that may be affected by excavation noise or disturbances but also the archaeological sites.
In some cases, marine life interacts with or inhabits underwater archaeological sites. PAM helps archaeologists understand these interactions by tracking the presence and behaviour of marine species around such sites. This information can be vital for both archaeological research and conservation efforts.
These examples highlight how PAM is revolutionizing the field of marine archaeology by providing new ways to explore, protect, and understand our underwater cultural heritage.
BOEM's New Regulations and PAM
The Bureau of Ocean Energy Management (BOEM) recently introduced new regulations to protect marine archaeological resources from potential harm caused by offshore oil and gas activities. Under these regulations, companies must submit an archaeological report before beginning any work on the U.S. Outer Continental Shelf. This report must include procedures for identifying and protecting underwater cultural sites.
PAM technology can play a crucial role in creating these reports. By using PAM to survey areas before any disturbance occurs, companies can ensure they are not inadvertently damaging archaeological sites. This aligns with BOEM’s goals of protecting cultural heritage and promoting responsible development of offshore resources.
Why is this Important? The ocean is vast, and much of it remains unexplored. As we push further into offshore energy development, the risk of disturbing unknown archaeological sites increases. PAM offers a way to explore these areas responsibly, helping to balance the needs of energy development with the preservation of our cultural heritage.