Kauai geology: Nothing's where you think it is

Was Kaua`i formed by one or two volcanoes, and if it’s one, was its center was near the Alakai Swamp? 

The newest and best answer seems to be one volcano—and the Alakai Swamp is not its center.

Researchers studying gravity anomalies appear to have answered a troubling geological question: how to make sense of the geological history of an island that’s been eroding for 5 million years, leaving a confusing array of ridges, cliffs, bogs and craters.

Three University of Hawai`i scientists, Ashton F. Flinders, Garrett Ito and Michael O. Garcia, all of the university’s Department of Geology and Geophysics, used gravity data to take another look.

Their 2010 paper in the Journal of Geophysical Research, which we came across recently, discusses the gravity fields in the Kaua`i-Ni`ihau area. 

Since the dense rock of a volcanic core—a solidified magma reservoir—can create a higher gravity reading, they were able to identify what appear to be the centers of the ancient volcanoes of Kaua`i County.

The essence of their findings is this: Kaua`i was formed of a single volcano, whose center was under what’s currently known as the Lihue Basin. It is generally in the middle of an area bounded by the Hā`upu range to the south, the Kahili-Wai`ale`ale cliffs to the west, the Makaleha Mountains to the north and the Kalepa Ridge to the east. What happened to the old volcanic peak? “The summit of the volcano was likely removed by extensive mass wasting and/or erosion.”

That volcanic center is six miles east of the Alakai Swamp region, which many experts had assumed marked the center—the geologically mapped caldera. “This offset suggests that the mapped caldera is a collapsed feature later filled in with lava and not the long‐term center of Kaua’i shield volcanism.”

The data was collected using more than 300 land measurements, which were added to work performed on Kaua`i gravity anomalies in 1965.

In another bit of interesting data, they identified a second area of high gravity in the middle of the channel between Kaua`i and Ni`ihau, which they say is likely the heart of the older Ni`ihau volcano. Its center lies about 8 miles toward Kaua`i from Paniau, the highest point on remnant Ni`ihau. 

The island of Ni`ihau is a remnant of that volcano, most of whose eastern side was covered by Kaua`i lavas. The underwater gravity survey was performed using University of Hawai’i’s R/V Kilo Moana.

The geology of the islands has been challenging, in part because of their age and degree of erosion, the authors say: “Extensive mass wasting, erosion, and subsidence have obscured the extent, shape, and centers of their original shield volcanoes.”

There remain plenty of questions for geologists to answer, particularly about the association of these two islands, and whether they are both part of a single volcanic rift that had two significant centers of volcanism—one forming Niihau and the second later forming Kaua`i.

“The overall trend of these features from eastern Ni’ihau, through the Kaulakahi Channel, and inland to western Kaua’i, combined with the elongate trend of the residual gravity, supports previous interpretations of a long volcanic rift zone, the Mana ridge, passing through the present locations of both islands. Yet, whether this feature is an extension of the Ni’ihau volcanic center... a rift zone radiating away from Ni’ihau similar to Lō’ihi’s rift system , a shared rift zone fed by either shield volcanoes or a separate and entirely unrelated feature, remains unresolved,” the authors say.

There are also multiple questions and theories about the formation of the vast plateau that forms the Alakai, which has been called the world’s highest-elevation swamp, and which is a center for biodiversity in the Islands.

One theory is that the Alakai , which is a part of features called the Olokele Volcanics, does represent the ancient Kaua`i caldera, and that it was fed at an angle by a volcanic center many miles to the east. But there is no Hawaiian volcano with so great an offset between the magma center and the caldera.

Another theory is that “the Olokele feature formed late in the shield stage and is not part of Kaua’i’s long‐term center of volcanism.”

As to the theory of whether there could have been two volcanoes for Kaua`i, one creating the Lihue basin and the other creating the Olokele features of West Kaua`i? 

“We found no indications in either the surface gravity mapping or the inverted density structure to support the hypothesis that Kaua’i was formed by two sequentially buttressed shield volcanoes, each having a separate magma supply system.”

Another question is whether Kaua`i and Ni`ihau were ever connected above the surface of the sea. The authors say they were not—that Ni`ihau had already started a significant erosion trend before it encountered the Kaua`i lavas. And the summit of Ni`ihau may have been destroyed in a massive collapse of the island’s eastern flank.

Citation: Flinders, A. F., G. Ito, and M. O. Garcia (2010), Gravity anomalies of the Northern Hawaiian Islands: Implications on the shield evolutions of Kauai and Niihau, J. Geophys. Res., 115, B08412, doi:10.1029/2009JB006877

 

© Jan TenBruggencate 2012

A new Pacific climate resource: PacificRISA

There’s a new climate resource in the Islands, with both a new website and a new report on impacts of climate change. Its message: change is coming, but it’s really hard to tell just how much.

The goal of both the website and the report is to figure out what we know about climate change impacts on the Pacific, and what to do about it. 

But don’t look for firm predictions of climate change impacts. The new report, from the Pacific Island Regional Climate Assessment program at East-West Center, takes a measured approach.

Why? There is lots of Pacific data, but the study argues that some of it isn’t real useful in making long-term predictions. For one thing, “The high interannual and interdecadal variability of the climate in the Pacific Islands makes it difficult to discern long-term trends from short-term data.”

More on this later. Here is the bureaucratic description of the document.

“Climate Change and Pacific Islands: Indicators and Impacts is a report developed by the Pacific Islands Regional Climate Assessment (PIRCA) aimed at assessing the state of knowledge about climate change indicators, impacts, and adaptive capacity of the Hawaiian archipelago and the US-Affiliated Pacific Islands (USAPI). The PIRCA is a collaborative effort engaging federal, state, and local government agencies, non-government organizations, academia, businesses, and community groups to inform and prioritize their activities in the face of a changing climate.”

The website, PacificRISA.org, contains copies of the report and various other resources, including some nice graphics and interviews with folks about how climate change will affect their lives and businesses. 

The report, put together by Victoria W. Keener, John J. Marra, Melissa L. Finucane, Deanna Spooner and Margaret H. Smith, is one of a series that make up the National Climate Assessment (NCA) 2013 report. They represent Pacific RISA, NOAA and the Pacific Islands Climate Change Cooperative.

A lot of the information isn’t new. With increasing carbon dioxide levels in the atmosphere (see our related post), we can expect rising sea levels, warmer air temperatures especially at higher elevations, warmer oceans, more extreme rainfall events as well as more drought, and the results are that habitat for plants and animals will be changing.

Warmer weather will increase the elevations of mosquitoes, which carry forest bird disease like avian malaria. Thus, less Hawaiian forest bird habitat.

There are some telling points. We have long known that sea levels have been rising for the past century. The report notes that the rate of rise has doubled since 1990. It cites various studies saying sea levels could be six inches higher at the end of the century, or six feet higher.  The PacificRISA study doesn’t say which it thinks is more likely.

But is says whatever it is, it’ll be trouble.

“Increasing mean water levels and the possibility of more frequent extreme water-level events, and their manifestation as flooding and erosion, will threaten coastal structures and property, groundwater reservoirs, harbor operations, airports, waste water systems, sandy beaches, coral reef ecosystems, and other social and economic resources. Low islands are especially vulnerable over the near to mid-term (next 25 to 50 years), with impacts varying with location and depending on how natural sea-level variability combines with modest increases of mean levels.

Citation: Keener, V. W., Marra, J. J., Finucane, M. L.,Spooner, D., & Smith, M. H. (Eds.). (2012). Climate Change and PacificIslands: Indicators and Impacts. Report for The 2012 Pacific Islands RegionalClimate Assessment. Washington, DC: Island Press. 

© Jan TenBruggencate 2012

Solar panels use more energy than they make? A myth.

It takes energy and raw materials to build solar panels, but over their lifetimes, they more than make it back.

“It is sometimes said that photovoltaic (PV) solar electric panels require more energy for their production than they every produce during their lifetime. This seems to be the kind of ‘urban myth’ that is hard to eradicate,” says the Welsh Centre for Alternative Technology.

Solar power has burgeoned in the Islands and some have expressed concern over the life cycle cost—since it takes a lot of energy to manufacture them. Multiple studies put those concerns to rest.

The Welsh site suggests an energy payback time of 2.5 to 7 years, depending on assumptions about the panels and the amount of sunlight in the place the panels are used. It cites this British report in saying that the carbon footprint of solar panels is one-tenth that of plants burning fossil fuels.

A study posted on the state of Oregon’s website, performed by Good Company, notes that while solar panels consume energy while being built, they displace fossil fuel energy when used.

“The positive impacts of that displacement far outweigh the negative impacts of the production phase of the life cycle of silicon solar panels,” says the report, on the website of Oregon’s Office of Innovative Partnerships and Alternative Funding.

This study suggests that it can take one to four years to pay back the energy cost of manufacture, and since solar panels have an assumed 30-year life, the overall payback is 9 to 17 times the energy cost.

The study also argues that recycling of old solar panels is needed, and that it will allow the production of new panels at one-third the energy cost of building ones from raw materials.

The U.S. National Renewable Energy Lab, in this study on thepayback times for photovoltaics, says a lot of the calculation has to do with the type of photovoltaic panel you use

“Energy payback estimates for rooftop PV systems are 4, 3, 2, and 1 years:  4 years for systems using  current multicrystalline-silicon PV modules, 3 years for current thin-film modules, 2 years for anticipated multicrystalline modules, and 1 year for anticipated thin-film modules,” the NREL study says.

It goes on:

“With energy paybacks of 1 to 4 years and assumed life expectancies of 30 years, 87% to 97% of the energy that PV systems generate won’t be plagued by pollution, greenhouse gases, and depletion of resources. Based on models and real data, the idea that PV cannot pay back its energy investment is simply a myth.”

There are plenty of other studies on the issue. See the citations at the bottom of the NREL study for several of them.

© Jan TenBruggencate 2012

New CO2 highs, "as if no one is listening"

We’re switching to LED lighting, driving more efficient cars and buying Energy Star appliances, but little efficiency gains alone aren’t doing the job.

The world’s longest continuous record of atmospheric carbon dioxide levels—taken since 1958 at Mauna Loa Observatory—shows CO2 levels still rocketing upward. 

(Image: In 1957, David Keeling began measuring carbon dioxide levels at Mauna Loa Observatory, a spot 11,150 feet up the side of a mountain in the Pacific, presumably physically above the zone affected by shorter-term human activities. His graph of the changing gas levels starts in 1958. Source: NOAA.)

The rocketing upward, as the graph shows, has not moderated in recent years in spite of our efficiency efforts.

The initial reading in March 1958 was 314 parts per million CO2 in the atmosphere. With seasonal ups and downs, it has climbed to 394 last month.  That’s a 25 percent increase.  Here's the actual data from NOAA.

Where’s all that CO2 coming from? Despite our best-intentioned conservation and efficiency efforts, the globe continues to dump more of the gas into the atmosphere year after year. 

The 2012 record is expected to be a new high at 35.6 billion tonnes, according to a December 2012 report from the Global Carbon Project, at the Tyndall Centre for Climate Change Research at the University of East Anglia (UEA). It means we’re burning 58 percent more fossil fuel than in 1990.

Here is the abstract of their report, in the journal Nature Climate Change.

It’s frightening. The report says that it may be too late to reverse the climate change trend. 

That’s despite the fact that some industrialized countries are actually reducing some of their emissions. (see the graphs at the bottom ofthis supplementary information on the East Anglia report.) That reduction, though, could be more an impact of economic recession than actual efficiency and conservation.

Over here on Kaua`i, our electric utility, the Kaua`i Island Utility Cooperative, has also seen contracting electrical use—and thus reduced oil consumption.

Thus some of us are getting there, but as a planet, we’re not getting there nearly fast enough.

The world is discussing the issue at the United Nations climate talks in Doha, Quatar. The solution, if there is to be one, won’t be a few LEDs and hybrid cars, but rather, said U.N. climate chief Christiana Figueres, "a complete transformation of the economic structure of the world."

The BBC quoted Corinne Le Quere, director of the Tyndall Centre for Climate Change Research: “These latest figures come amidst climate talks in Doha, but with emissions continuing to grow, it's as if no-one is listening to the scientific community.”

An advocacy group for renewables, Oil Change International, notes that as we face this crisis, the industrialized world ironically continues to subsidize fossil fuels.

©Jan TenBruggencate 2012