Haleakalā, or the East Maui Volcano, is a massive shield volcano that forms more than 75% of the Hawaiian Island of Maui.

History

Early Hawaiians applied the name Haleakalā ("house of the sun") to the summit area only, most likely because from the west side of the island, the sun could be seen rising up over the eastern side of the mountain. In Hawaiian folklore, the depression at the summit of Haleakalā was home to the grandmother of the demigod Māui. According to the legend, Maui's grandmother helped him capture the sun and force it to slow its journey across the sky in order to lengthen the day. In modern times, Haleakalā has become synonymous with the entire East Maui volcano.

From the summit one looks down into a massive depression some 11.25 km (7 mi) across, 3.2 km (2 mi) wide, and nearly 800 m (2,600 ft) deep. The surrounding walls are steep and the interior mostly barren-looking with a scattering of volcanic cones. The volcano is officially considered active and has produced numerous eruptions in the last 30,000 years. This volcanic activity has been along two rift zones, the southwest and east. These two rift zones together form an arc that extends from La Perouse Bay on the southwest, through the Haleakalā Crater and to Hāna, to the east. The east rift zone continues under the ocean beyond the east coast of Maui as Haleakalā Ridge, making the combined rift zones one of the longest in the Hawaiian Islands chain.

Until recently, East Maui Volcano was thought to have last erupted around 1790, based largely on comparisons of maps made during the voyages of La Perouse and George Vancouver. Recent advanced dating tests, however, have shown that the last eruption was more likely to have been in the 1600s. These last flows from the southwest rift zone of Haleakalā make up the large lava deposits of the Ahihi Kina`u/La Perouse Bay area of South Maui. In addition, contrary to popular belief, Haleakalā "crater" is not volcanic in origin, nor can it accurately be called a caldera (which is formed through when the summit of a volcano collapses to form a depression). Rather, scientists believe that Haleakalā's "crater" was formed when the headwalls of two large erosional valleys merged at the summit of the volcano. These valleys formed the two large gaps — Ko‘olau on the north side and Kaupō on the south — on either side of the depression.

Macdonald, Abbott, & Peterson state it this way:

Haleakala is far smaller than many volcanic craters (calderas); there is an excellent chance that it is not extinct, but only dormant; and strictly speaking it is not of volcanic origin, beyond the fact that it exists in a volcanic mountain.

National Park

Surrounding and including the "crater" is Haleakala National Park, a 28,655 acre (115.963 km²) park of which 19,270 acres (77.983 km²) are wilderness. The park includes the summit depression, Kipahulu Valley on the southeast, and ‘Ohe‘o Gulch (and pools), extending to the shoreline in the Kipahulu area. From the summit, there are two main trails leading into Haleakalā: Sliding Sands Trail and Halemau‘u Trail.

The temperature near the summit tends to vary between about 40°F (5°C) and 60°F (16°C) and, especially given the thin air and the possibility of dehydration at that elevation, the walking trails can be more challenging than one might expect. Despite this, Haleakala is popular with tourists and locals alike, who often venture to its summit, or to the visitor center just below the summit, to view the sunrise.

Astrophysical research

Because of the remarkable clarity, dryness, and stillness of the air, and its location above one-third of the atmosphere, as well as the absence of the lights of major cities, the summit of Haleakala (like Mauna Kea) is one of the most sought-after locations in the world for ground-based telescopes. As a result of the geographic importance of this observational platform, experts come from all over the world to take part in research at "Science City", an astrophysical complex operated by the U.S. Department of Defense, University of Hawaii, Smithsonian Institution, Air Force, Federal Aviation Agency, and others.

Some of the telescopes operated by the US Department of Defense are involved in researching man-made (e.g. spacecraft, monitoring satellites, rockets, and laser technology) rather than celestial objects. The program is in collaboration with defense contractors in the new Maui Research and Technology Park in Kihei. The astronomers on Haleakala are concerned about increasing light pollution as Maui's population grows. Nevertheless, new telescopes are added, such as the Pan-STARRS in 2006.

credited to wikipedia and flickr: Walt K