In 1978, a US Geological Survey research ship collected dredge samples and photographed Lōʻihi's summit with the goal of studying whether Lōʻihi is active. Analysis of the photos and testing of pillow lava rock samples appeared to show that the material was "fresh", yielding more evidence that Lōʻihi is still active. An expedition from October 1980 to January 1981 collected further dredge samples and photographs, providing additional confirmation. Studies indicated that the eruptions came from the southern part of the rift crater. This area is closest to the Hawaiʻi hotspot, which supplies Lōʻihi with magma. Following a 1986 seismic event, a network of five ocean bottom observatories (OBOs) were deployed on Lōʻihi for a month. Lōʻihi's frequent seismicity makes it an ideal candidate for seismic study through OBOs. In 1987, the submersible DSV Alvin was used to survey Lōʻihi.