Hawaii

Comparing the Hawaiian and Channel Islands

Introduction

Although they are separated by only a few thousand miles, it is still possible to discover similarities and differences between the two island groups. There are several categories of similarities that one can consider. For example the formation of islands in the group, ecology concerns (both terrestrial & marine), tectonic plate movement, island attractions, and of course the weather. Similarly, there are differences between the two island groups that one can also consider. For example, the number of islands, the length of the island chain, and new island growth. We shall take a look at some of these similarities and differences in the paragraphs below.

The Similarities of the Islands

Formation

Formation of the two island chains is similar in that they are all of volcanic origin (except San Nicolus in the Channel Islands). Igneous rocks may be found on all the Channel Island islands, again, except San Nicolus. All of the Hawaiian Islands and all islands in the Hawaiian-Emperor chain are also compose entirely of igneous rock.

The Hawaiian Hot Spot has persisted for at least 75 million years. In its lifetime thus far, it has generated about 200 Hawaiian-type volcanoes, most of them now submerged, during its lifetime and is still going strong. With respect to the Channel Islands, on the other hand, scientists estimate that around 15 million years ago the Channel was a hotbed of volcanic activity - much like Hawaii is today. Over the years, the Channel Islands have been formed through a combination of volcanic activity namely, pushing molten magma to the earth's surface - in this case at times underwater.

Erosion from the sea as ocean water levels have risen and lowered as much as 300 feet during different ice and warming ages. This results in a wearing away the islands as a result of surf and tide conditions, and seismic activity, the lifting and folding associated with earthquakes and other long term movements of the earth's crust.

Ecology Concerns

Terrestrial

In both the Hawaiian Island and Channel Island chains terrestrial ecology concerns are primarily the same. In the Channel Islands one of the biggest concerns of late is the status of endangered plants. These endangered plants are native or endemic plants that are in danger of being eradicated due to human impact on the environment and that require close attention in order to preserve them as part of the earth's natural bio-diversity. Factors such as pollution, trash, improper care and maintenance of existing native or endemic plants.

In the Hawaiian Islands, the silent invasion of ecosystems by animals, insects, disease organisms, weeds, and other pests is the single greatest threat to Hawaii's economy and natural environment and to the health and lifestyle of Hawaii's people. Pests already cause millions of dollars in crop losses, the extinction of native species, the destruction of native forests, and the spread of disease. But many more harmful pests now threaten to invade Hawaii and wreak further damage. Even one new pest could forever change the character of the islands. Stopping the influx of new pests and containing their spread is essential to Hawaii's future well being.

The Hawaii Eco-region faces grave threats, including the destruction of native species and ecosystems; pollution of air and water; overuse of natural resources; over-dependence on imported energy; and massive development by the tourism industry. The region is truly at a crossroads as we near the 21st century: If these trends are not stopped, the natural values that make these islands so extraordinary will be lost forever. These threats can be turned back only with a comprehensive, ecosystem-based strategy.

Marine

In the Channel Islands, water is one the most currently debated geographic issues in the California Channel region today. The population based has expanded far beyond the locally available water supply, and at the beginning of the 20th century, dark, smoky room deals were made to channel water from the Colorado River to southern California to promote massive development. Lives were lost, fortunes made, and several ecosystems irreparably damaged in the process of bringing water to California's expanded southern populations. If we were to see the Channel region in prehistory, its watercourses would look very different than today. The natural streams and river networks were sufficient to support thousands of Chumash and Gabrielinos for generations. But it would not have been able to support the massive development that has occurred since California became a member of the United States. Of course, pollution of the ocean is of great concern as well.

The waters that swirl around the five islands within the Channel Islands National Marine Sanctuary combine warm and cool currents to create an exceptional breeding ground for many species of plants and animals. Forests of giant kelp are home to numerous populations of fish and invertebrates. Every year over 27 species of whales and dolphins visit or inhabit the sanctuary including the rare blue, humpback and sei whales. On the islands, seabird colonies and pinniped rookeries flourish while overhead brown pelicans and Western gulls search the water for food. Major issues that impact the sanctuary include oil and gas development, busy shipping lanes in nearby waters, nonpoint source pollution, and commercial and recreational fishing.

In the Hawaiian Islands, one of the major concerns is the coral reef ecosystem in Hawaii which thrive in clear, nutrient-poor waters. These systems generally overlie porous and permeable limestone, providing pathways for the movement of toxic and nutrient-rich ground water. Small increases in the nutrient content of coastal waters (associated with fertilizer and sewage discharge) may upset the fragile balance necessary to maintain the health of economically important coral reefs. Additional detrimental effects may be caused as well by increased turbidity due to anthropogenic activity and by increased salinity due to poor water management practices.

Another major concern is the disposal of dredge spoils in the near offshore area, coupled with the rapid growth of Honolulu and other nearby municipalities, has placed increased stress on the environment of Mamala Bay. No satisfactory bathymetric map of the seafloor had existed, and little information has been compiled about the effects of these activities to determine whether modifications to the operation and management of the designated dump sites and sewage outfall locations were necessary.

Attractions (tourists)

With respect to both the Hawaiian Islands and the Channel Islands, the basic tourist attractions are fundamentally, unlimited. On both islands chains, depending on which island one considers, there is abundant, but are not limited to birding, boating, camping, diving, fishing, hiking, photography, and wildlife watching.

With respect to the Hawaiian Islands, larger and more diverse than all the other Hawaiian Islands, the Big Island continues to grow as its active volcanoes send lava down their slopes to the sea below. The landscape varies from snow-covered mountains, to grassy plains populated by cattle and cowboys, to rain forests filled with the fragrance of orchids. Here you can tour Hawaii Volcanoes National Park, the famous Parker Ranch, or the Place of Refuge for a look at the history and culture of Hawaii. The other islands offer their own unique attractions as well.

With respect to the Channel Islands, there are a number of things to do while enjoying Channel Islands National park. One could join a National Park Service ranger to explore Channel Island's natural and cultural history. Another alternative is to join a ranger to learn about the forces that once shaped this landscape - and continue to do so, or enjoy the many Naturalist programmes which include scheduled talks. Programmes are provided by park naturalists year-round. These are just some of the ways to discover the diversity of the scenic, natural and historic wonders that comprise Channel Islands National Park. As with the Hawaiian Islands, each of the Channel Islands have their unique attractions and contributions.

The Mainland Visitor Center of the Channel Islands features a museum, living tide-pool exhibit, three-dimensional models of all the park islands, interactive touch-screen exhibit, a tower with telescopes for viewing the islands, picnic area overlooking the Ventura Harbor, a bookstore, and an outdoor native plant garden. Visitors will enjoy the 25-minute park movie, "A Treasure in the Sea", throughout the day in the auditorium. Every Saturday and Sunday park rangers present free interpretive programs on the natural and cultural resources of the park. Throughout the week, other programmes and school visits may be scheduled by calling the visitor centre. All facilities are fully accessible.

Tectonic Plate Movement

Since both island chains lie within the Pacific tectonic plate, we find that the annual movement of the islands is about the same. Recently, GPS technology and data analysis have matured to the point where GPS data are often used to form velocity vectors ultimately applied in research by investigators other than those who acquired the original data. UNAVCO already plays a major role in this process via archiving of raw and GPS data and exchange of results via community meetings. Using the UNAVCO software package, it was found that the Channel Islands (using Santa Catalina for example), are moving at approximately 48.31 mm/year in the direction of 297.38o as measure from North (0o) clockwise. Almost the same numbers are generated when volcano Kilauea in the Hawaiian Island chain is examined. Using the same programme, Kilauea is found to be moving at approximately 67.78 mm/year in the direction of 296.87o.

Weather

In the Channel Islands, the climate is mild, with little variation in temperature year round. However, one must be prepared for high winds, fog, and sea spray at any time. Visitors to the islands should dress in layers, with short and long pants, windbreaker, hat, sunscreen, and waterproof outer clothing. Sturdy hiking shoes with non-slip soles should also be worn. Although most visitations occur in the summer, migrating gray whales and spectacular wildflower displays attract visitors in the winter and spring. Autumn is an excellent time to travel to the park, as well as for diving, as the days are usually sunny, with minimal winds and clear ocean water.

In the Hawaiian Islands, they say, "If you don't like the weather, wait ten minutes." This phrase best describes Hawaiian weather. Most of the year Hawaii experiences winds from the Northeast at 10-25kts. These winds are so predictable that the old sailing ships called them the "trade winds", since they could be relied upon. August through April are generally the lightest wind months of the year. May, June and July have the most consistent winds and sailing during this time is exhilarating. The hallmark of the winter season is the combination of light winds and cool nights. When the wind blows in the winter, however, it is generally the strongest of the year. Kauai is known as the garden island; this name was given to Kauai by the ancient Hawaiians. The wettest place on earth is at the centre of this island, Mt. Waialeale. This area receives in excess of 400 inches of rain annually.

The Differences of the Islands

# of Islands

The number of islands in either chain is greatly different from the Channel Islands and the Hawaiian-Emperor chain. In the Channel Islands there are only 8 islands; San Miguel, Santa Rosa, Santa Cruz, Anacapa, Santa Barbara, San Nicolus, Santa Catalina, and San Clemente. In the Hawaiian-Emperor chain there are literally hundreds of islands, seamounts and several underwater volcanoes.

Length of Island Chains

The Hawaiian-Emperor vs. the Channel Island chain differs greatly in their lengths. The Hawaiian-Emperor chain consists of about 200 volcanoes and is 5,500 kilometers long. The volcanoes range in age from 75 million-year-old volcanoes at the northwestern end, near Siberia, to the present day active volcanoes at Kilauea and Mauna Loa at the southeastern end.

The Channel Islands chain is much shorter than the Hawaiian-Emperor chain. It is only approximately 215 Km in length and the volcanic origins are all approximately 15 million years of age.

New Island Growth

In the Channel Islands there is currently no new islands in the making and no signs that there will be any new islands in the future. The Hawaiian Islands, on the other hand, seem to be in constant new island making since it is over an active, live hot spot. The newest island currently under development in the Hawaiian Islands is the Loihi Seamount. All islands to the west of Hawaii, in the Hawaiian-Emperor chain, are older and not currently subject to new island growth due to the current hot spot location.

The Loihi Seamount is the youngest Hawaiian volcano, still hidden by the Pacific Ocean. Its summit is 1 kilometer below sea level and 30 kilometers southeast of the island of Hawaii. Earthquake swarms centered beneath Loihi in 1971-2 and in 1975, and fresh lava samples dredged by oceanographic ships from its summit and sides indicate that Loihi is very much alive. One surprise finding from detailed echo soundings of the submarine topography around Loihi (which means "the long one") is that collapse craters and rift zones apparently exist on this young submarine volcano.

No one is sure of the age of the Loihi Seamount. Its age can be estimated only by its present size and the known growth rate of Kilauea Volcano, on whose south flank Loihi is found. Kilauea has been growing at a rate of about one-tenth of a cubic kilometer per year for the past few decades, and the volume of Loihi is about 100 cubic kilometers. This implies that Loihi is only about 1,000 years old, but perhaps young Hawaiian volcanoes grow slowly compared to their later growth rate. It is clear only that there is much yet to be learned about the youthful stages of Hawaiian volcanoes.

Written By
R. B. Trombley, Ph.D.
Southwest Volcano Research Centre
Apache Junction, Arizona USA