page_title: Lōʻihi Seamount
section_title: Early work
hierarchical_section_title: Lōʻihi Seamount / Exploration / Early work
caption_attribution_description: English: Pisces V being launched from research vessel R/V Kaimikai-o-Kanaloa. Pisces V is a three-person, battery-powered, one-atmosphere submersible operating with one pilot and two observers. Dive duration is six to eight hours, with a depth capacity of 200 m (6300 ft). It offers scientists direct observation, photographic and video records, instrument placement, sample collecting, and environmental monitoring.
context_page_description: Lōʻihi Seamount is an active submarine volcano about 35 km off the southeast coast of the island of Hawaii. The top of the seamount is about 975 m below sea level. This seamount is on the flank of Mauna Loa, the largest shield volcano on Earth. Lōʻihi, meaning "long" in Hawaiian, is the newest volcano in the Hawaiian–Emperor seamount chain, a string of volcanoes that stretches about 6,200 km northwest of Lōʻihi. Unlike most active volcanoes in the Pacific Ocean that make up the active plate margins on the Pacific Ring of Fire, Lōʻihi and the other volcanoes of the Hawaiian–Emperor seamount chain are hotspot volcanoes and formed well away from the nearest plate boundary. Volcanoes in the Hawaiian Islands arise from the Hawaii hotspot, and as the youngest volcano in the chain, Lōʻihi is the only Hawaiian volcano in the deep submarine preshield stage of development.
  Lōʻihi began forming around 400,000 years ago and is expected to begin emerging above sea level about 10,000–100,000 years from now. At its summit, Lōʻihi Seamount stands more than 3,000 m above the seafloor, making it taller than Mount St. Helens was before its catastrophic 1980 eruption.
context_section_description: Lōʻihi Seamount's first depiction on a map was on Survey Chart 4115, a bathymetric rendering of part of Hawaiʻi compiled by the US Coast and Geodetic Survey in 1940. At the time, the seamount was non-notable, being one of many in the region. A large earthquake swarm first brought attention to it in 1952. That same year, geologist Gordon A. MacDonald hypothesized that the seamount was actually an active submarine shield volcano, similar to the two active Hawaiian volcanoes, Mauna Loa and Kīlauea. Macdonald's hypothesis placed the seamount as the newest volcano in the Hawaiian–Emperor seamount chain, created by the Hawaiʻi hotspot. However, because the earthquakes were oriented east–west (the direction of the volcanic fault) and there was no volcanic tremor in seismometers distant from the seamount, Macdonald attributed the earthquake to faulting rather than a volcanic eruption.
  Geologists suspected the seamount could be an active undersea volcano, but without evidence the idea remained speculative. The volcano was largely ignored after the 1952 event, and was often mislabeled as an "older volcanic feature" in subsequent charts. Geologist Kenneth O. Emery is credited with naming the seamount in 1955, describing the long and narrow shape of the volcano as Lōʻihi. The Hawaiian word lōʻihi means "long". In 1978, an expedition studied intense, repeated seismic activity known as earthquake swarms in and around the Lōʻihi area. Rather than finding an old, extinct seamount, data collected revealed Lōʻihi to be a young, possibly active volcano. Observations showed the volcano to be encrusted with young and old lava flows. Fluids erupting from active hydrothermal vents were also found.
  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.
  Another autonomous observatory was positioned on Lōʻihi in 1991 to track earthquake swarms.
caption: R/V (research vessel) Kaʻimikai-o-Kanaloa (KoK) launching Pisces V, a battery-powered submersible. The R/V KoK is the support ship for the Hawaiʻi Undersea Research Laboratory (HURL).
exif: {}