Lower campus parking lot sits atop a coral bed

By: Georgia Clair Johnson-King

30 November 2020

In 2007, the University of Hawaiʻi at Mānoa moved forward with plans to construct a new $30 million lower campus parking lot upon the Moʻiliʻili Quarry. To avoid another parking lot falling through, the location of the new parking lot needed to be specific.
 

“We have good local evidence that if you don’t pay attention to what the foundations are like you’re going to have a lot of trouble because the ground sinks,” said Peter Mouginis-Mark, a researcher at the Hawaiʻi Institute of Planetary Geophysics and Planetology.
 

The parking lot is built atop an extinct coral bed, exposed due to the excavation of the rock that
covered it.


“If you go to the Diamond Head and Makai corner, you can see a big structure,” Mouginis-Mark said. “That used to be a small parking lot, about a quarter of the size. In the past they have built three different structures which all stopped because the foundations weren’t strong enough.”
 

When building the new structure, the University of Hawai’i had to work with the landscape as according to Mouginis-Mark, there’s a series of lava tubes below it. What is recognized as ʻthe Quarry’ is the result of a geological phenomenon. Three volcanic
vents erupted, Tantalus, Sugarloaf, and Roundtop causing a lava flow throughout Manoa valley less than 100,000 years ago.

A volcanic vent is an opening in the earth’s crust that releases molten rock or volcanic gases.


“When you get into the elevator going up to the law school, that cliff face it’s a single lava flow,” Mouginis-Mark said. Mouginis-Mark is referring to the elevator needed to ascend the five levels of the lower campus parking lot.

 

A lava flow is a result of the eruption of basalt magma – the liquid rock that explodes out of volcanoes.


The Moʻiliʻili Quarry was turned into a parking lot for UH Mānoa students after it was purchased for the university in 1949 by the state of Hawaiʻi.

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“The discussion was, what are we going to do with this big hole in the ground!” said Dr Mouginis-Mark. “Stonemasonʻs cut so much of the building material for downtown Honolulu, that they got down so low that they couldn’t get decent foundations for any tall buildings so they had to put something that had less weight and the parking structure was ideal!”

Photo Credit: “Compositional heterogeneity of the Sugarloaf melilite nephelinite flow,
Honolulu Volcanics, Hawai‘i.” Published in Geochimica et Cosmochimica Acta, 2016

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