Kamaʻehuakanaloa Seamount: Difference between revisions
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{{Infobox Seamount |
{{Infobox Seamount |
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| Name=Lō{{okina}}ihi Seamount |
| Name=Lō{{okina}}ihi Seamount |
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| Map=[[File:Hawaii Island topographic map-en-loihi.svg|300px]] |
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| Map= |
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| Depth= {{convert|969|m|ft|0}}<ref name="USGS">{{cite web |url=http://hvo.wr.usgs.gov/volcanoes/loihi/ |title=Lo`ihi Seamount Hawai`i's Youngest Submarine Volcano |date=26 March 2000 |work=Hawaiian Volcano Observatory |publisher= [[United States Geological Survey]] (USGS) |accessdate=2009-03-01}}</ref> |
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| Depth= 975 m (3,200 ft) |
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| Height= |
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| Height= {{convert|3000|m|ft|0}}<ref name="Scholastic Atlas">{{cite book |last=Rubel|first=David |others=Proofreader: Laura Mattue |title=Scholastic Atlas of the United States |editor=Ron Boudreau |publisher=Scholastic |date=2001 |edition=First |pages=144 |accessdate=2009-01-02}}</ref> |
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| Summit = |
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| Summit = Volume-660 km3 (160 mi3)<ref name="USGS" /> |
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| Location= Southeast of [[Island of Hawaii]] |
| Location= Southeast of [[Island of Hawaii]] |
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| Group= |
| Group= |
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| Coordinates ={{coord|18.92|N|155.27|W|type: |
| Coordinates ={{coord|18.92|N|155.27|W |type:mountain_region:US-HI |display=inline,title}}<ref name="Smithsonian" >[http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-00- Smithsonian Institution Global Volcanism Program: Loihi Seamount] Accessed 2009-03-01</ref> |
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| Country = |
| Country = [[Hawaii]], [[USA]] |
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| Type=[[Submarine volcano]] |
| Type=[[Submarine volcano]] |
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| Volcanic group=[[Hawaiian-Emperor seamount chain]] |
| Volcanic group=[[Hawaiian-Emperor seamount chain]] |
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| Age= |
| Age= |
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| Last eruption=1996 (active) <ref |
| Last eruption=1996 (active) <ref name="USGS" /> |
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| Discovered= |
| Discovered= |
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| Discovered_by= |
| Discovered_by= |
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| First_visit= |
| First_visit= |
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| Language= [[Hawaiian language|Hawaiian]] |
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| Translation= |
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| Translation= The name ''Lo`ihi'' means "long" in Hawaiian and was introduced in 1955 to describe the elongate shape of the seamount.<ref name="USGS" /> |
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| Pronunciation= |
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| Pronunciation=Lō{{okina}}ihi |
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| Photo=Loihiflank.jpg |
| Photo=Loihiflank.jpg |
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| Photo caption= Yellow iron oxide covered lava rock on the flank of Lō{{okina}}ihi. |
| Photo caption= Yellow iron oxide covered lava rock on the flank of Lō{{okina}}ihi. |
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'''Lō{{okina}}ihi''' ("Long" in Hawaiian) is an active undersea [[volcano]]. Loihi lies approximately 30 miles southeast of Hawaii, on the flank of the gigantic [[Shield volcano|shield volcano]] [[Mauna Loa]]. Loihi's activity level is expected to increase as the underwater volcano builds up height, and it will eventually breach sea level and become the newest Hawaiian island. Loihi is home to a diverse [[Loihi_Seamount#Ecology|microbial community]] around its many [[Hydrothermal vent|hydrothermal vents]]. Loihi is taller then [[St. Helens|Mount Saint Helens]] was in spite of being {{convert|975|m|ft|0}} underwater. |
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'''Lō{{okina}}ihi''' is a [[seamount]] and undersea [[volcano]] in the [[Hawaiian Islands|Hawaiian archipelago]], located at 18.92° N, 155.27° W — roughly 30 km (19 mi) south of the southeast coast of the [[Hawaii Island|Island of Hawai{{okina}}i]]. It is one of three active volcanoes (the other two are [[Mauna Loa]] and [[Kilauea|Kīlauea]]) thought to presently sit over the [[Hawaii hotspot]]. The greatest distance between the summits of these volcanoes is about 80 km (50 mi), approximately the diameter of the hot spot. Lō{{okina}}ihi has yet to build to the [[sea level|surface of the ocean]], although it is now over 3,000 m (10,000 ft) high (taller than [[Mount St. Helens]]). The top of Lō{{okina}}ihi lies 975 m (3,200 ft) below the surface.<ref>[http://www.volcano.si.edu/world/volcano.cfm?vnum=1302-00- Smithsonian Institution Global Volcanism Program: Loihi Seamount]</ref> If the rate of upward building is about the same as nearby Kīlauea, Lō{{okina}}ihi should appear at the surface in several tens of thousands of years. |
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In 1996 Loihi was rocked by a large eruption, the first ever recorded of an active eruption by an underwater volcano in [[Hawaii]]. The eruption was preceded by an [[earthquake swarm]] measuring 4000 hits, the largest of any Hawaiian volcanic eruptions. A total of 4 to 5 square miles of the summit was altered; one section, called :Pele's Vents", collapsed entirely upon itself, and formed the renamed "Pele's Pit." The volcano has remained relatively active and under the watchful eye of the scientific community ever since, including a probe, ''HUGO'', that provided real-time data from [[1997]] to [[2002]]. |
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Like Kīlauea, Lō{{okina}}ihi lies on the flank of [[Mauna Loa]], the largest [[shield volcano]] on the planet. The summit has a [[caldera]]-like depression, and three [[volcanic crater|crater]]s. The crater called Pele's Pit is known to have formed in July 1996 when a vent collapsed forming a [[depression (geology)|depression]] with 200 m (660 ft) high, vertical walls. The [[rift zone]] for this volcano is about 31 km (19 mi) long and oriented northwest-southeast across the 2.8 by 3.7 km (1.7 × 2.3 mi) caldera. The eruption in 1996 was confirmed by scientists at the [[University of Hawaii|University of Hawai{{okina}}i]], becoming the first such confirmation of an active eruption occurring on a seamount. In 1997,<ref name="ShapiroLevin">{{cite web |url= http://www.hanahou.com/pages/magazine.asp?Action=DrawArticle&ArticleID=573&MagazineID=37 |title= Earth, Whales & Fire |author= Michael Shapiro |work= [[Hana Hou!]] Vol. 10, No. 3, June/July 2007 |publisher= Photo by Wayne Levin |quote= In 1997, [[University of Hawaii at Manoa#School of Ocean and Earth Science and Technology|University of Hawai‘i]] scientists installed the Hawai‘i Undersea Geo-Observatory (HUGO), a submarine observatory designed to monitor a newly hatched volcano… Among HUGO's instruments was a [[hydrophone]] (a submersible microphone) to listen in on the eruption… HUGO went offline in 1998 after its power supply failed, but it left behind hours of recordings of haunting, unearthly sounds that had never before reached human ears: [[Humpback Whale|humpback whales]] [[Whale song|singing]] against the backdrop of a volcanic eruption. }} ([http://www.soest.hawaii.edu/HUGO/about_hugo.html About HUGO, on the Loihi Seamount].)</ref> the university installed a submarine observatory on the summit of Loihi Seamount. Another active undersea volcano, named Vailu{{okina}}ulu{{okina}}u, was confirmed in 2001 in the [[Manua|Manu{{okina}}a Group]], [[Samoa]]. |
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Lō{{okina}}ihi is being studied by manned [[submersible]] dives to its surface and placement of recording instruments and remote [[observatory|observatories]] on the summit. The volcano is actively venting [[hydrothermal]] fluids and thermal vents there are being studied for [[thermophilic]] [[extremophile]]s (organisms associated with extreme temperature conditions). In 1999, a never before seen [[Jellyfish|jelly]]-like organism surrounding the 160°C vents was collected for [[incubation]] and study at NSF's [[Marine Bioproducts Engineering Center]] (MarBEC). |
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==Geology== |
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==References and external links== |
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===General characteristics=== |
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[[File:LoihiBathemetric.jpg|thumb|left|200px|Bathemetric mapping of Loihi. The arrow in the picture points to Pele's Pit.]] |
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[[File:Loihi 3d.gif|thumb|left|200px|3D Rendering of the Seamount]] |
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Like all of the Hawaiian volcanoes, Loihi grew from eruptions along a {{convert|31|km|m|0}} long [[rift zone]] that runs northwest and southeast of the [[caldera]], called the [[Hawaiian-Emperor seamount chain]]. Loihi is built on a seafloor that slopes about 5 degrees. Loihi's northern base is {{convert|1900|m|ft}} below sea level, whereas its southern base is a much more substantial {{convert|4755|m|ft}} below the tide. Thus, the summit is {{convert|931|m|ft|0}} above the seafloor as measured from the base of its north flank, yet {{convert|3786|m|ft|0}} high when measured from the base of its southern flank.<ref name="USGS" /> |
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The greatest distance between the summits of the three volcanoes is around {{convert|80|km|m|0}}, about the diameter of the [[hot spot]]. Lō{{okina}}ihi has yet to [[sea level|breach the ocean]], even though it measures {{convert|3000|m|ft|0}} high, taller than [[Mount St. Helens]]. The top of Lo{{okina}}ihi lies {{convert|975|m|ft|0}} beneath the waves.<ref name="Smithsonian" /> Continued volcanism from the island will eventually build a new island at Loihi. Estimates for breach range from roughly 10,000 to 100,000 years.<ref name="Smithsonian" /> |
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Lo{{okina}}ihi lies on the flank of [[Mauna Loa]], the largest [[shield volcano]] on the planet. The summit has a [[caldera]]-like depression, and sports three [[volcanic crater|crater]]s. The biggest of these craters, Pele's Pit, formed in July 1996 when a vent collapsed into a large [[depression (geology)|depression]] with {{convert|200|m|ft}} walls.<ref name="NOAA">{{cite web |url=http://www.oar.noaa.gov/spotlite/archive/spot_loihi.html |title=Loihi Submarine Volcano:A unique, natural extremophile laboratory |last=Malahoff|first=Alexander |date=12/18/00 |publisher=USA Office of Oceanic and Atmospheric Research |accessdate=2009-03-01}}</ref> |
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The [[rift zone]] for this volcano is about {{convert|31|km|mi|0}} long and oriented northwest-southeast across the 2.8 by 3.7 km (1.7 × 2.3 mi) top. |
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===Activity=== |
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Loihi is a young and fairly [[Active volcano|active]] volcano, though not as much as the nearby [[Hualālai]]. |
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Loihi has been attributed to several [[Earthquake swarm|earthquake swarms]] (an event that precedes volcanic eruptions) in the last few decades. Activity has been recorded, most recently, in [[1986]], [[1989]], [[1990]], [[1991]], [[1993]], [[1995]], [[2001]], [[2002]], [[2005]] and [[2006]].<ref name="Rec. Updates">{{cite web|url=http://www.soest.hawaii.edu/GG/HCV/loihiupdates.html|title=Recent Activity at Loihi Volcano|work=Loihi "Status"|publisher=Hawaii Center For Volcanology|accessdate=2009-03-07}}</ref> Activity from the volcano has been recorded as far back as records go. Of the most recent, only one escalated into a full-blown volcanic eruption, in [[1996]]. |
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====1996 Event==== |
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By far the largest amount of activity coming from Loihi occurred in [[1996]]. An [[Earthquake swarm|earthquake swarm]] numbering about 4,000 occurred between July 16th and August 9th, 1996.<ref name="USGS" /> |
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This show of strength was the largest swarm of earthquake activity generated by a volcano at any Hawaiian volcano, lasting about two months in the summer of 1996. A total of over 4,000 earthquakes were recorded by the Hawaii Volcano Observatory (HVO) network and confirmed by scientists at the [[University of Hawaii|University of Hawai{{okina}}i]], the first ever confirmation of an active eruption by a Hawaiian seamount. A total of about 40 earthquakes measuring between magnitudes 4 and 5 were also referenced by the worldwide seismic network.<ref name="1996 Eruption Summary">{{cite web |url=http://www.soest.hawaii.edu/GG/HCV/loihi_j_a_1996.html |title=The 1996 Eruption at Loihi Volcano |last=Rubin|first=Ken|date=1996 |publisher=Hawaiian Center for Volcanology |accessdate=2009-03-01}}</ref> |
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The event was very important and well-studied by the scientific community for several reasons. Firstly, it was the first ever directly obsevered eruption of an undersea volcano,<ref name="Hawaii Center for Volcanology Main" /><ref name="1996 Eruption Summary" /> and thus provided valuable clues to the nature of underwater volcanism. Secondly, eruptions from the volcano could possibly become dangerous if they exceeded a certain point, as a full-blown eruption could cause a [[Tsunami|tsunami]]. It was important to come up with some way to monitor the active volcano directly (a solution later found in HUGO). Lastly, the volcano offered a rare chance to study specimen of Iron-Oxidizing Bacteria, a poorly understood but vital part of the underwater ecosystem.<ref name="SciJournal" /><ref name="NOAA" /> |
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On August 1996, a [[National Science Foundation]]-funded expedition to Loihi by University of Hawaii scientists began investigating the event and its [[Origin (start)|origin]]. Follow-up expeditions to Loihi, including a series of [[Submersible|manned-submersible]] dives in August and September, were also called. A great deal of shore-based research was conducted as well.<ref name="1996 Eruption Summary" /> |
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The eruption itself occurred over a period of two weeks, and was most directly observed by a quick response cruise that was launched soon after the volcano erupted. Led by [[Frederick Duennebier]] and [[Francis Sansone]], it was tasked with responding to the event. Their assessment laid the groundwork for the many expeditions that followed.<ref name="HURL">{{cite web |url=http://www.soest.hawaii.edu/HURL/hurl_loihi.html |title=HURL Current Research- Loihi after the July-August event |date=2001|work=Official Publication of 2001 Marine Expedition |publisher=HURL - Hawaii's Undersea Research Laboratory (University of Hawaii) |accessdate=2009-03-01}}</ref> |
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The quick response dives were followed by extensive [[NOAA]]-funded work in September and October. Investigators included [[Gary McMurtry]] and [[Francis Sansone]], [[Alexander Malahoff]], and [[James Cowen]]. New dives were called that revealed the extent of the damage done. The southern portion of Loihi's summit had collapsed, a result of multiple swarms of seafloor-originating earthquakes and the rapid withdrawal of magma from the system. A [[Crater|crater]] {{convert|1|km|mi}} across and {{convert|300|m|ft|0}} deep formed out of the rubble, an event that most likely involving the downward movement of 100 million cubic meters of [[Volcano#Ash|volcanic material]]. A total of 4 to 5 square miles of the summit was altered. The area was populated by bus-sized [[Igneous#Extrusive igneous rocks|pillow lava blocks]], precariously perched along the outer rim of the newly formed crater. "Pele's Vents," an area on the southern side, previously considered stable, had collapsed completely into a giant pit, aptly renamed "Pele's Pit." Seawater was flowing down into the newborn pit on the northern end of the volcano, mixing with loose minerals and bacterial matter before flowing out over Loihi's western edge. The resulting strong current make submersible diving relatively hazardous in the region.<ref name="HURL" /> |
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Studies following the eruption found clouds of hydrothermal [[sulfide]] and [[sulfate]] minerals coating everything. It was soon learned that a sudden collapse of Pele's Vents had caused a large discharge of hydrothermal material, composed of magmatic gases and sulfide crystals. The presence of certain rare minerals in the mixture indicated high temperatures exceeding 250°C, a record.<ref name="The Canadian Mineralolagist" /> Most strikingly, the composition of the materials was similar to that of [[Black smokers|black smokers]], the hydrothermal vent plumes located along [[Mid-Ocean Ridge|Mid-Ocean Ridges]] that are a habitat for [[Extremophile|archea extremophiles]]. Samples from mounds, built by discharges from the hydrothermal plumes, resembled [[White smoker|white smokers]]. [[Dissolution]] and [[oxidation]] of the mineral observed over the two years following suggest that the sulfate is not easily preserved.<ref name="The Canadian Mineralolagist">{{cite web|url=http://pubs.nrc-cnrc.gc.ca/mineral/tcm-45741-2.html|title=Sulfide formation related to changes in the hydrothermal system on Loihi Seamount, Hawai'i, following the seismic event in 1996|coauthors=Alicé S. Davis, David A. Clague, Robert A. Zierenberg, C. Geoffrey Wheat, and Brian L. Cousens|work=Scientific Journal|publisher=The Canadian Mineralagist|pages=Volume 41, number 2, Pages 457-472|accessdate=2009-03-07}}</ref> |
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In the study it also was learned that the most volcanically and hydrothermicly active area was along the southern rift. Dives on the less active northern rim showed a more stable terrain compared to before, and high [[Lava|lava columns]] were still standing upright.<ref name="HURL" /> |
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====Recent Activity==== |
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After the [[1996]] event, Loihi has remained largly quiet. The intermission between activity carried from [[2002]] to [[2004]]. In [[2005]] the seamount showed signs of life again by sending a rumbler bigger then any ever recorded before. USGS-ANSS (Advanced National Seismic System) reported two [[Earthquake|quakes]], [[Richter magnitude scale|magnitudes]] 5.1 and 5.4, on May 13th and July 17th.<ref name="Rec. Updates" /> Both originated from {{convert|44|km|mi}} deep. On April 23d a magnitude 4.3 quake was recorded at about {{convert|33|km|mi}} deep.<ref name="Rec. Updates" /> Between late 2005 and early 2006 a swarm of about 100 quakes, the largest measuring 4 on the [[Richter scale]] and being {{convert|12|km|mi|0}} to {{convert|28|km|mi|0}} deep, occured, lasting from December 7th 2005 to January 18th 2006.<ref name="Rec. Updates" /> Another earthquake measuring 4.7 was later recorded, roughly midway between Loihi and Pahala (on the South Coast of the [[Hawaii (Island)|Main Island]]).<ref name="Rec. Updates" /> |
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==Exploration== |
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[[File:Pisces V.jpg|thumb|right|220px|''Pisces V'' being launched from R/V ''Ka'imikai-o-Kanaloa''.]] |
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===Before and during the eruption=== |
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[[File:Loihi bot.jpg|280px|left|thumb|A temperature probe being inserted into the vent orifice; note the extensive deposits of Irone oxides surrounding the vent opening.]] |
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The exploration of the Loihi has been underway since 1970, following an expedition that whose goal was to study an [[earthquake swarm]] (intense, repeated seismic activity) that had just occurred in the area. Data collected revealed that Loihi was a young, active volcano, rather than an old dead seamount from a bygone era. The volcano is encrusted with young and old lava flows and is actively venting hydrothermal fluids.<ref name="Hawaii Center for Volcanology Main">[http://www.soest.hawaii.edu/GG/HCV/loihi.html Hawaii Center for Volcanology Main] Accessed 2009-02-01.</ref> |
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In a dive was conducted almost immediately after seismic activity was reported in [[1996]], visibility was highly reduced by high concentrations of displaced minerals and large floating mats of bacteria in the water. The bacteria, which feed on the dissolved nutrients, have already begun colonizing the new hydrothermal vents at Pele's Pit (formed from the collapse of the old ones), and may be indicators of the kinds of material ejected from the newly formed vents. They were carefully sampled for further analysis in a laboratory.<ref name="HURL" /> |
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Repeated multibeam [[Bathymetric chart|bathymetric mapping]] were ued to disclose the exact changes in the summit following the 1996 collapse. [[Hydrothermal vent|Hydrothermal plume]] surveys confirmed changes in the energy and dissolved minerals emanating from Loihi. HURL's {{convert|2000|m|ft|0}} capable submersible ''Pisces V'' allowed scientists to sample the vent waters, microorganisms, and hydrothermal mineral deposits.<ref name="NOAA" /> |
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[[File:Ocean Bottom Observatory at Pele's Vent.jpg|thumb|right|OBO- '''O'''cean '''B'''ottom '''O'''bservatory.|230px]] |
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In 1997,<ref name="Rec. Updates" /> the university installed a submarine observatory, scientifically named "Ocean Bottom Observatory," (OBO) on the summit of Loihi Seamount. The machine was nicknamed "HUGO," (Hawaii Undersea Geological Observatory). HUGO was connected to the shore, {{convert|34|km|mi}} away, by a long fiber optic cable. It gave give scientists real-time seismic, chemical and visual information about the state of Loihi, which had become an international laboratory for the study of undersea volcanism.<ref name="HURL" /> The cable that provided HUGO power and communications broke in October 1998, effectively shutting it down. On January 19th of the following year, ''HUGO'' was visited by ''Pisces V''. It was discovered that a "Junction Box" regulating the flow of power to the observatory had been flooded with seawater.<ref name="Rec. Updates" /> The failed portion was successfully repaired, and a new [[hydrophone]] was installed. The first new recording to reach the listening station at Honuapo was that of a whale's song, but the volcano itself remained quiet. Divers noted that HUGO's junction box was half-buried in volcanic mud, which should help to keep it stable for many years to come. The observatory carried on for 4 more years before it went dead again in [[2002]].<ref name="Rec. Updates" /> [[University of Hawaii]]'s [[Fred Duennebier]], the developer of HUGO and leader of the expeditions, expects to see it back on Loihi in the future, after improving are made and the line is protected with steel armor.<ref name="Rec. Updates" /> |
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===Current and future exploration=== |
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Lō{{okina}}ihi is being studied by manned [[submersible]] dives to its surface and placement of recording instruments and remote [[observatory|observatories]] on the summit for many years. The volcano is actively venting [[hydrothermal]] fluids and the local thermal vents are being studied for [[thermophilic]] [[extremophile]]s (organisms associated with extreme temperature conditions). |
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Future work on Loihi will carefully monitor ongoing changes and assess the risks of explosive volcanism or devastating landslides. |
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==Ecology== |
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[[File:LoihiBacteria.jpg|thumb|left|300px|A vent on Loihi Seamount, as well as a small snapshot of the bacteria populating its surface.]] |
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[[File:PiscesV.jpg|thumb|right|200px|Pisces V underwater.]] |
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Loihi is home to a unique and well-studied microbial community. |
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Loihi's mid-Pacific location and its well-sustained hydrothermal system contributed to a rich oasis for the microbial [[ecosystem]]. |
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The [[Crater|crater floor]] and north slope of Loihi are areas of extensive [[Hydrothermal vent|hydrothermal venting]].<ref name="NOAA" /> Hydrothermal vent sites also exist on the summit of Loihi Seamount. The vents are {{convert|1100|m|ft}} to {{convert|1325|m|ft}} below the surface, and range in [[temperature]] from 10 to 167° Celsius.<ref name="SciJournal">{{cite web |url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=123976 |title=Neutrophilic Fe-Oxidizing Bacteria Are Abundant at the Loihi Seamount Hydrothermal Vents and Play a Major Role in Fe Oxide Deposition |coauthors=David Emerson and Craig L. Moyer |date=2002 |work=Scientific Journal |publisher=American Society for Microbiology |accessdate=2009-03-02}}</ref> The vent fluids are characterized by a high concentration of {{chem|CO|2}} (up to 17 mM) and Fe ([[Iron]]), but low in [[sulfide]]. Low oxygen and [[pH]] are important factors in supporting the high Fe (iron) concentrations, one of the hallmark features of Loihi. These characteristics make a perfect environment for iron-oxidizing bacteria, called FeOB, to thrive in.<ref name="FeMO Intro">{{cite web |url=http://earthref.org/cgi-bin/er.cgi?s=http://earthref.org/FEMO/loihi.htm |title=Introduction to the Biology and Geology of Loihi Seamount |work=FeMO Article |publisher=FeMO - Fe-Oxidating Microbial Observatory |accessdate=2009-03-02}}</ref> |
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A diverse community of [[Microbial mat|microbial mats]] surround the vents and virtually cover Pele's Pit. |
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The [[Hawaii Undersea Research Laboratory]] (HURL), NOAA's National Undersea Research Center for Hawaii and the Western Pacific, monitors and researches the Loihi hydrothermal systems and studies the local community.<ref name="NOAA" /> |
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The National Science Foundation (NSF) funded a [[extremophile]] sampling expedition to Loihi in 1999. Microbial mats surrounded the 160°C vents, and including a never before seen [[Jellyfish|jelly]]-like organism. Samples were collected for study at NSF's [[Marine Bioproducts Engineering Center]] (MarBEC).<ref name="NOAA" /> |
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In 2001, ''[[Pisces V]]''<ref name="HURL" /> collected samples of the organisms and brought them to the surface for study. |
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Currently, NOAA's National Undersea Research Center (HURL) and NSF's Marine Bioproducts Engineering Center (MarBEC) are cooperating to sample and reaserch the local bacteria and archea [[extremophiles]].<ref name="NOAA" /> |
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==See Also== |
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*[[Evolution of Hawaiian volcanoes]] |
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*[[Hawaii hotspot]] |
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*[[Seamount]] |
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==References== |
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{{reflist}} |
{{reflist}} |
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==External links== |
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* Hazlett, R. W., and D. W. Hyndman. 1996. ''Roadside Geology of Hawai{{okina}}i''. |
* Hazlett, R. W., and D. W. Hyndman. 1996. ''Roadside Geology of Hawai{{okina}}i''. |
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* [http://www.soest.hawaii.edu/GG/HCV/loihi.html Hawai{{okina}}i Center for Volcanology], University of Hawai{{okina}}i. |
* [http://www.soest.hawaii.edu/GG/HCV/loihi.html Hawai{{okina}}i Center for Volcanology], University of Hawai{{okina}}i. |
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* [http://hvo.wr.usgs.gov/volcanoes/loihi/ Lō{{okina}}ihi Seamount] — USGS website. |
* [http://hvo.wr.usgs.gov/volcanoes/loihi/ Lō{{okina}}ihi Seamount] — USGS website. |
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* [http://www.oar.noaa.gov/spotlite/archive/spot_loihi.html Lō{{okina}}ihi Submarine Volcano: A unique, natural extremophile laboratory] — NOAA research site. |
* [http://www.oar.noaa.gov/spotlite/archive/spot_loihi.html Lō{{okina}}ihi Submarine Volcano: A unique, natural extremophile laboratory] — NOAA research site. |
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* [http://www.soest.hawaii.edu/HURL/hurl_loihi.html 2001 Loihi Seamount Exploration] Homepage of the 2001 Loihi Seamount Exploration |
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* |
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* [http://www.soest.hawaii.edu/GG/HCV/loihiupdates.html Recent Activity] Up-to-date recent activity. |
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* [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=123976 Neutrophilic Fe-Oxidizing Bacteria Are Abundant at the Loihi Seamount Hydrothermal Vents and Play a Major Role in Fe Oxide Deposition] Details of Bacteria. |
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[[Category:Submarine volcanoes|Loihi]] |
[[Category:Submarine volcanoes|Loihi]] |
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[[Category:Seamounts of the Pacific Ocean]] |
[[Category:Seamounts of the Pacific Ocean]] |
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[[Category:Hotspot volcanoes]] |
[[Category:Hotspot volcanoes]] |
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[[Category:Seamounts]] |
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[[de:Lōʻihi]] |
[[de:Lōʻihi]] |
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Revision as of 22:26, 8 March 2009
Lōʻihi ("Long" in Hawaiian) is an active undersea volcano. Loihi lies approximately 30 miles southeast of Hawaii, on the flank of the gigantic shield volcano Mauna Loa. Loihi's activity level is expected to increase as the underwater volcano builds up height, and it will eventually breach sea level and become the newest Hawaiian island. Loihi is home to a diverse microbial community around its many hydrothermal vents. Loihi is taller then Mount Saint Helens was in spite of being 975 metres (3,199 ft) underwater.
In 1996 Loihi was rocked by a large eruption, the first ever recorded of an active eruption by an underwater volcano in Hawaii. The eruption was preceded by an earthquake swarm measuring 4000 hits, the largest of any Hawaiian volcanic eruptions. A total of 4 to 5 square miles of the summit was altered; one section, called :Pele's Vents", collapsed entirely upon itself, and formed the renamed "Pele's Pit." The volcano has remained relatively active and under the watchful eye of the scientific community ever since, including a probe, HUGO, that provided real-time data from 1997 to 2002.
Geology
General characteristics
Like all of the Hawaiian volcanoes, Loihi grew from eruptions along a 31 kilometres (31,000 m) long rift zone that runs northwest and southeast of the caldera, called the Hawaiian-Emperor seamount chain. Loihi is built on a seafloor that slopes about 5 degrees. Loihi's northern base is 1,900 metres (6,200 ft) below sea level, whereas its southern base is a much more substantial 4,755 metres (15,600 ft) below the tide. Thus, the summit is 931 metres (3,054 ft) above the seafloor as measured from the base of its north flank, yet 3,786 metres (12,421 ft) high when measured from the base of its southern flank.[1]
The greatest distance between the summits of the three volcanoes is around 80 kilometres (80,000 m), about the diameter of the hot spot. Lōʻihi has yet to breach the ocean, even though it measures 3,000 metres (9,843 ft) high, taller than Mount St. Helens. The top of Loʻihi lies 975 metres (3,199 ft) beneath the waves.[3] Continued volcanism from the island will eventually build a new island at Loihi. Estimates for breach range from roughly 10,000 to 100,000 years.[3]
Loʻihi lies on the flank of Mauna Loa, the largest shield volcano on the planet. The summit has a caldera-like depression, and sports three craters. The biggest of these craters, Pele's Pit, formed in July 1996 when a vent collapsed into a large depression with 200 metres (660 ft) walls.[4] The rift zone for this volcano is about 31 kilometres (19 mi) long and oriented northwest-southeast across the 2.8 by 3.7 km (1.7 × 2.3 mi) top.
Activity
Loihi is a young and fairly active volcano, though not as much as the nearby Hualālai. Loihi has been attributed to several earthquake swarms (an event that precedes volcanic eruptions) in the last few decades. Activity has been recorded, most recently, in 1986, 1989, 1990, 1991, 1993, 1995, 2001, 2002, 2005 and 2006.[5] Activity from the volcano has been recorded as far back as records go. Of the most recent, only one escalated into a full-blown volcanic eruption, in 1996.
1996 Event
By far the largest amount of activity coming from Loihi occurred in 1996. An earthquake swarm numbering about 4,000 occurred between July 16th and August 9th, 1996.[1] This show of strength was the largest swarm of earthquake activity generated by a volcano at any Hawaiian volcano, lasting about two months in the summer of 1996. A total of over 4,000 earthquakes were recorded by the Hawaii Volcano Observatory (HVO) network and confirmed by scientists at the University of Hawaiʻi, the first ever confirmation of an active eruption by a Hawaiian seamount. A total of about 40 earthquakes measuring between magnitudes 4 and 5 were also referenced by the worldwide seismic network.[6]
The event was very important and well-studied by the scientific community for several reasons. Firstly, it was the first ever directly obsevered eruption of an undersea volcano,[7][6] and thus provided valuable clues to the nature of underwater volcanism. Secondly, eruptions from the volcano could possibly become dangerous if they exceeded a certain point, as a full-blown eruption could cause a tsunami. It was important to come up with some way to monitor the active volcano directly (a solution later found in HUGO). Lastly, the volcano offered a rare chance to study specimen of Iron-Oxidizing Bacteria, a poorly understood but vital part of the underwater ecosystem.[8][4]
On August 1996, a National Science Foundation-funded expedition to Loihi by University of Hawaii scientists began investigating the event and its origin. Follow-up expeditions to Loihi, including a series of manned-submersible dives in August and September, were also called. A great deal of shore-based research was conducted as well.[6]
The eruption itself occurred over a period of two weeks, and was most directly observed by a quick response cruise that was launched soon after the volcano erupted. Led by Frederick Duennebier and Francis Sansone, it was tasked with responding to the event. Their assessment laid the groundwork for the many expeditions that followed.[9]
The quick response dives were followed by extensive NOAA-funded work in September and October. Investigators included Gary McMurtry and Francis Sansone, Alexander Malahoff, and James Cowen. New dives were called that revealed the extent of the damage done. The southern portion of Loihi's summit had collapsed, a result of multiple swarms of seafloor-originating earthquakes and the rapid withdrawal of magma from the system. A crater 1 kilometre (0.62 mi) across and 300 metres (984 ft) deep formed out of the rubble, an event that most likely involving the downward movement of 100 million cubic meters of volcanic material. A total of 4 to 5 square miles of the summit was altered. The area was populated by bus-sized pillow lava blocks, precariously perched along the outer rim of the newly formed crater. "Pele's Vents," an area on the southern side, previously considered stable, had collapsed completely into a giant pit, aptly renamed "Pele's Pit." Seawater was flowing down into the newborn pit on the northern end of the volcano, mixing with loose minerals and bacterial matter before flowing out over Loihi's western edge. The resulting strong current make submersible diving relatively hazardous in the region.[9]
Studies following the eruption found clouds of hydrothermal sulfide and sulfate minerals coating everything. It was soon learned that a sudden collapse of Pele's Vents had caused a large discharge of hydrothermal material, composed of magmatic gases and sulfide crystals. The presence of certain rare minerals in the mixture indicated high temperatures exceeding 250°C, a record.[10] Most strikingly, the composition of the materials was similar to that of black smokers, the hydrothermal vent plumes located along Mid-Ocean Ridges that are a habitat for archea extremophiles. Samples from mounds, built by discharges from the hydrothermal plumes, resembled white smokers. Dissolution and oxidation of the mineral observed over the two years following suggest that the sulfate is not easily preserved.[10]
In the study it also was learned that the most volcanically and hydrothermicly active area was along the southern rift. Dives on the less active northern rim showed a more stable terrain compared to before, and high lava columns were still standing upright.[9]
Recent Activity
After the 1996 event, Loihi has remained largly quiet. The intermission between activity carried from 2002 to 2004. In 2005 the seamount showed signs of life again by sending a rumbler bigger then any ever recorded before. USGS-ANSS (Advanced National Seismic System) reported two quakes, magnitudes 5.1 and 5.4, on May 13th and July 17th.[5] Both originated from 44 kilometres (27 mi) deep. On April 23d a magnitude 4.3 quake was recorded at about 33 kilometres (21 mi) deep.[5] Between late 2005 and early 2006 a swarm of about 100 quakes, the largest measuring 4 on the Richter scale and being 12 kilometres (7 mi) to 28 kilometres (17 mi) deep, occured, lasting from December 7th 2005 to January 18th 2006.[5] Another earthquake measuring 4.7 was later recorded, roughly midway between Loihi and Pahala (on the South Coast of the Main Island).[5]
Exploration
Before and during the eruption
The exploration of the Loihi has been underway since 1970, following an expedition that whose goal was to study an earthquake swarm (intense, repeated seismic activity) that had just occurred in the area. Data collected revealed that Loihi was a young, active volcano, rather than an old dead seamount from a bygone era. The volcano is encrusted with young and old lava flows and is actively venting hydrothermal fluids.[7]
In a dive was conducted almost immediately after seismic activity was reported in 1996, visibility was highly reduced by high concentrations of displaced minerals and large floating mats of bacteria in the water. The bacteria, which feed on the dissolved nutrients, have already begun colonizing the new hydrothermal vents at Pele's Pit (formed from the collapse of the old ones), and may be indicators of the kinds of material ejected from the newly formed vents. They were carefully sampled for further analysis in a laboratory.[9]
Repeated multibeam bathymetric mapping were ued to disclose the exact changes in the summit following the 1996 collapse. Hydrothermal plume surveys confirmed changes in the energy and dissolved minerals emanating from Loihi. HURL's 2,000 metres (6,562 ft) capable submersible Pisces V allowed scientists to sample the vent waters, microorganisms, and hydrothermal mineral deposits.[4]
In 1997,[5] the university installed a submarine observatory, scientifically named "Ocean Bottom Observatory," (OBO) on the summit of Loihi Seamount. The machine was nicknamed "HUGO," (Hawaii Undersea Geological Observatory). HUGO was connected to the shore, 34 kilometres (21 mi) away, by a long fiber optic cable. It gave give scientists real-time seismic, chemical and visual information about the state of Loihi, which had become an international laboratory for the study of undersea volcanism.[9] The cable that provided HUGO power and communications broke in October 1998, effectively shutting it down. On January 19th of the following year, HUGO was visited by Pisces V. It was discovered that a "Junction Box" regulating the flow of power to the observatory had been flooded with seawater.[5] The failed portion was successfully repaired, and a new hydrophone was installed. The first new recording to reach the listening station at Honuapo was that of a whale's song, but the volcano itself remained quiet. Divers noted that HUGO's junction box was half-buried in volcanic mud, which should help to keep it stable for many years to come. The observatory carried on for 4 more years before it went dead again in 2002.[5] University of Hawaii's Fred Duennebier, the developer of HUGO and leader of the expeditions, expects to see it back on Loihi in the future, after improving are made and the line is protected with steel armor.[5]
Current and future exploration
Lōʻihi is being studied by manned submersible dives to its surface and placement of recording instruments and remote observatories on the summit for many years. The volcano is actively venting hydrothermal fluids and the local thermal vents are being studied for thermophilic extremophiles (organisms associated with extreme temperature conditions).
Future work on Loihi will carefully monitor ongoing changes and assess the risks of explosive volcanism or devastating landslides.
Ecology
Loihi is home to a unique and well-studied microbial community. Loihi's mid-Pacific location and its well-sustained hydrothermal system contributed to a rich oasis for the microbial ecosystem.
The crater floor and north slope of Loihi are areas of extensive hydrothermal venting.[4] Hydrothermal vent sites also exist on the summit of Loihi Seamount. The vents are 1,100 metres (3,600 ft) to 1,325 metres (4,347 ft) below the surface, and range in temperature from 10 to 167° Celsius.[8] The vent fluids are characterized by a high concentration of CO
2 (up to 17 mM) and Fe (Iron), but low in sulfide. Low oxygen and pH are important factors in supporting the high Fe (iron) concentrations, one of the hallmark features of Loihi. These characteristics make a perfect environment for iron-oxidizing bacteria, called FeOB, to thrive in.[11]
A diverse community of microbial mats surround the vents and virtually cover Pele's Pit. The Hawaii Undersea Research Laboratory (HURL), NOAA's National Undersea Research Center for Hawaii and the Western Pacific, monitors and researches the Loihi hydrothermal systems and studies the local community.[4]
The National Science Foundation (NSF) funded a extremophile sampling expedition to Loihi in 1999. Microbial mats surrounded the 160°C vents, and including a never before seen jelly-like organism. Samples were collected for study at NSF's Marine Bioproducts Engineering Center (MarBEC).[4] In 2001, Pisces V[9] collected samples of the organisms and brought them to the surface for study.
Currently, NOAA's National Undersea Research Center (HURL) and NSF's Marine Bioproducts Engineering Center (MarBEC) are cooperating to sample and reaserch the local bacteria and archea extremophiles.[4]
See Also
References
- ^ a b c d e f "Lo`ihi Seamount Hawai`i's Youngest Submarine Volcano". Hawaiian Volcano Observatory. United States Geological Survey (USGS). 26 March 2000. Retrieved 2009-03-01.
- ^ Rubel, David (2001). Ron Boudreau (ed.). Scholastic Atlas of the United States. Proofreader: Laura Mattue (First ed.). Scholastic. p. 144.
{{cite book}}:|access-date=requires|url=(help) - ^ a b c Smithsonian Institution Global Volcanism Program: Loihi Seamount Accessed 2009-03-01
- ^ a b c d e f g Malahoff, Alexander (12/18/00). "Loihi Submarine Volcano:A unique, natural extremophile laboratory". USA Office of Oceanic and Atmospheric Research. Retrieved 2009-03-01.
{{cite web}}: Check date values in:|date=(help) - ^ a b c d e f g h i "Recent Activity at Loihi Volcano". Loihi "Status". Hawaii Center For Volcanology. Retrieved 2009-03-07.
- ^ a b c Rubin, Ken (1996). "The 1996 Eruption at Loihi Volcano". Hawaiian Center for Volcanology. Retrieved 2009-03-01.
- ^ a b Hawaii Center for Volcanology Main Accessed 2009-02-01.
- ^ a b "Neutrophilic Fe-Oxidizing Bacteria Are Abundant at the Loihi Seamount Hydrothermal Vents and Play a Major Role in Fe Oxide Deposition". Scientific Journal. American Society for Microbiology. 2002. Retrieved 2009-03-02.
{{cite web}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ a b c d e f "HURL Current Research- Loihi after the July-August event". Official Publication of 2001 Marine Expedition. HURL - Hawaii's Undersea Research Laboratory (University of Hawaii). 2001. Retrieved 2009-03-01.
- ^ a b "Sulfide formation related to changes in the hydrothermal system on Loihi Seamount, Hawai'i, following the seismic event in 1996". Scientific Journal. The Canadian Mineralagist. pp. Volume 41, number 2, Pages 457-472. Retrieved 2009-03-07.
{{cite web}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ "Introduction to the Biology and Geology of Loihi Seamount". FeMO Article. FeMO - Fe-Oxidating Microbial Observatory. Retrieved 2009-03-02.
External links
- Hazlett, R. W., and D. W. Hyndman. 1996. Roadside Geology of Hawaiʻi.
- Hawaiʻi Center for Volcanology, University of Hawaiʻi.
- Lōʻihi Seamount — USGS website.
- Lōʻihi Submarine Volcano: A unique, natural extremophile laboratory — NOAA research site.
- 2001 Loihi Seamount Exploration Homepage of the 2001 Loihi Seamount Exploration
- Recent Activity Up-to-date recent activity.
- Neutrophilic Fe-Oxidizing Bacteria Are Abundant at the Loihi Seamount Hydrothermal Vents and Play a Major Role in Fe Oxide Deposition Details of Bacteria.