Elevation: 8,278 feet (2,523 m)
 

This page information is based on field observations, trip lectures, and several outside references.

Hualalai is located on the western side of the Big Island.  The volcano is divided by three rifts that radiate to the south, north, and northwest.  The building of this shield volcano was completed approximately 120,000 years ago.  105,000 years ago a trachyte dome, Puu Waawaa, was created along the north rift and generated lava flows that traveled about 6 miles.  Hualalai last erupted during 1800 and 1801.  During this eruption the lava flows reached the ocean which is about 25 miles away.  In fact, the airport that is situated next to Hualalai is resting on lava flows from the 1800 eruption, along with most of the town (resorts, houses, businesses, etc.).

Big Island, Hawaii

image from:

 http://volcano.und.edu/vwdocs/volc_images/north_america/hawaii/big_island.html, (and then modified by Sierra Sellman)

Taking a Closer Look At the Lava on Hualalai

                Lava Composition    

• Contains tholeiitic basalt and picritic tholeiitic basalt of the shield stage and has exposed alkalic basalt, ankaramite, and trachyte of the postshield stage. All other lavas are unknown or absent. (http://www.geocities.com/volcano_hawaii/hualalai/)

   

  • Origin of alkalic rocks:

     

    • At least two different processes in the mantle can produce alkalic magmas. These are (1) low degrees of melting of peridotite source rocks in the mantle or (2) differentiation of tholeiitic magmas at high pressures.

                    Background           

     ~ This photo, taken by the USGS, shows an aerial view of Hualalai summit craters, which I found at Rob Pacheco's "Reading the land; Monthly Essay" website: http://www.hawaii-forest.com/essays/9704.html

     ~ As you can see this volcano has multiple cinder cones along its flanks

Hualalai is well known for its mantle xenoliths.  In fact during our trip, our group found a lava flow rich in olivine xenoliths off Highway 190, 9 mi North of Kailia, at mile-marker 27.  The xenoliths that we found ranged in size from 1-2mm to 30cm!  Most of the xenoliths were ellipsoid in shape, with a coarse grained texture, and mostly olivine (some with pyroxene) in composition.  The colors ranged from a brilliant olive green to a dark rust red color.  The rust red color was due to the weathering of the olivine crystals.  The vast majority of these xenoliths are from the 1800-1801 Kaupulehu A'a flow. 

Xenoliths

These pictures show an example of an olivine-clinopyroxene bearing mantle xenolith from the 1800-1801 lava flow of Hualalai. A thin coating of host lava mantles the rock (image on right is about 15 cm wide) source: http://www.soest.hawaii.edu/GG/HCV/hualalai.html

            History           

The oldest rocks are dated to be from 128,000 years ago, but geologists believe that this volcano grew out of the sea (above sea level) about 300,000 years ago.  Making Hualalai the second oldest volcano on Big Island, just in front of Mauna Kea.

Approximately 80% of the Hualalai's flanks are covered with lava that was deposited during the past 5,000 years. There have been only one (two) eruption(s) in recorded history  since 1790 A.D., the 1800 and 1801 eruption which involved 6 separate vents.  As a result this volcano has been classified as extinct and in an post-shield stage volcanism.  The post-shield stage classification is described as a volcano that erupts primarily alkalic basalt with some variations. Typically it will erupt about every fifty years, but there have been cases of volcanoes pausing for up to 500 years between episodes.  However, there was an event in 1929 where several earthquakes were recorded within the volcano.  It has been hypothesized that these were due to a magma body rising from the deep, which is key indicator of a volcanoes explosivity.  Before this lava body/intrusion could reach the surface it cooled and formed a network of dikes.  From the magnitude and frequency of these earthquakes geologists and scientists have theorized that this volcano will erupt in the next 100 years.

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sources:

• http://www.soest.hawaii.edu/GG/HCV/hualalai.html

• http://gsa.confex.com/gsa/2002AM/finalprogram/abstract_43242.htm

  • FAY, Lisa C., WISCHER, Stephanie, and KILINC, Attila, Department of Geology, Univ of Cincinnati, P.O. Box 210013, Cincinnati, OH 45221-0013, faylc@email.uc.edu

• http://hvo.wr.usgs.gov/volcanoes/hualalai/

• http://www.geocities.com/volcano_hawaii/hualalai/

Albion College geology students and professors created these web pages as a follow-up to our March 2003 Geology 210 Regional Field Geology class trip to Hawaii.  The images, except where noted, are a product of our trip.  We make them available for non-profit, educational uses.  As a condition of use, we request that you inform the page author or Thom Wilch.  Thank You.