Lord Howe Island is a small, mountainous island located in the Tasman Sea, about 600 kilometers off the coast of New South Wales, Australia. The island is of volcanic origin, and it is believed to be the remnant of a much larger volcanic island that was formed about 7 million years ago. Over time, the island has been eroded and submerged, and only a small portion of the original island remains above sea level.

In order to trace the underwater volcanic ancestry of Lord Howe Island, scientists have used a variety of methods, including:

* Bathymetric mapping: This technique uses sonar to map the depth of the ocean floor. By studying the bathymetry of the area around Lord Howe Island, scientists have been able to identify a number of underwater features that are associated with volcanic activity, such as seamounts and volcanic cones.

* Petrology: This technique involves studying the composition of rocks to determine their origin. By analyzing the rocks on Lord Howe Island, scientists have been able to identify the type of volcanic activity that formed the island.

* Geochemistry: This technique involves studying the chemical composition of rocks and minerals to determine their origin. By analyzing the geochemistry of the rocks on Lord Howe Island, scientists have been able to identify the source of the magma that formed the island.

By using these methods, scientists have been able to trace the underwater volcanic ancestry of Lord Howe Island and learn more about the geological history of the region.