Simulating the Gravity Signature of Underwater Ammunition Dumps

Abstract

We are investigating the underwater use of gravimeters to search for dumped munitions in the Baltic Sea. After the second world war, a lot of munition, bombs and chemical weapons were dumped into the ocean. These hazardous substances pose a danger to people, maritime life and the construction of infrastructure such as wind farms, pipelines and submarine cables. Optical sensors require clear visibility, which is quickly reduced with increasing depth and by murky water. Gravimeters may be able to identify dump sites regardless of visibility, including those covered by sediments. Additionally, gravimeters are able to determine the total mass of a found site which can otherwise be easily underestimated and thus is very helpful for salvage and disposal.

In the past, gravimeters have already been used on board of ships and remotely operated vehicles. Applications cover geophysical and oceanographic research, and the search and monitoring of natural resources. The search for sunken munitions is more difficult because the masses are smaller. We expect the magnitude of the signal to be around 10nm/s^2 depending on the objects and the distance of the sensor. This scenario is a big challenge with current gravimeters.

We are in the process of developing a realistic simulation environment in which we compare different scenarios and propose a set of requirements necessary for the successful operation of such a mission. We plan to formulate requirements for the gravimeter, the mobile platform including supporting sensors and the survey path. In practice the supporting sensors will be crucial for the success. This will allow future (quantum) gravimeters to be designed suitable for this application.

We will present an overview of our project, show the simulated signal for a real munition dump and the first evaluations of such a signal embedded into the environment observed in different scenarios.