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Hualālai (pronounced [huəˈlaːlei] in Hawaiian) is the third-most historically active shield volcano on the Island of Hawaiʻi in the Hawaiian Islands. Its peak is at 8,271 ft (2,521 m) above sea level. Hualālai lies more or less due west of the saddle between the much taller Mauna Kea and Mauna Loa mountains, and forms the backdrop to the town of Kailua-Kona. In fact, the town is built on the southwestern slope of this mountain, where most of the world famous Kona coffee is grown.

Structure

Hualālai is built from a well-defined (hi) rift zone that trends approximately N50°W across its summit and a less well-defined rift zone that trends northward from a point 3 mi east of the summit (Macdonald and Abbott, 1970). The oldest dated rocks on the mountain surface are about 128,000 years before present (0.1 MYA). It is estimated that the volcano appeared above sea level some 300,000 years ago (0.3 MYA; USGS).

Over 100 cinder and spatter cones are arranged along the rift zones. There is no summit caldera, just a collapse crater (~ 0.3 mile across) at the top of a small lava shield. Much of the southern slope (above the town of Kailua-Kona) consists of lava flows covered by a layer of volcanic ash from 10 cm (a few inches) to a meter (3 ft) thick. Hualālai appears to have entered the late stage of the eruptive cycle of Hawaiian volcanoes

The Island of Hawaiʻi is built from five separate shield volcanoes that erupted somewhat sequentially, one overlapping the other. These are (from oldest to youngest):

Hualalai is a shield volcano located on Hawaii. The summit of Hualalai is 8271 ft. (2523 m.) above sea level. This volcano is farthest west of all the 5 major Hawaiian volcanoes. It is found at 19.69°N, 155.87°W in the middle of the Pacific Ocean. The last eruption of Hualalai was in 1800-1801 along the northwest rift zone. When it erupted 6 vents opened up and caused craters to occur. It is to be considered the third most active volcano in Hawaii, after Mauna Loa and Kilauea. It is on a hot spot in the middle of the Pacific plate. Hualalai grew above sea level approximately 300,000 years ago. ²—the post-shield stage¹.

Recent eruptions

Six vents erupted lava between the late 1700s and 1801, two of which generated lava flows that poured into the sea along the west coast of the island. The Keāhole-Kona Airport, located only 11 km (7 mi) north of Kailua-Kona, is built atop the smaller Huehue flow (1801) just north of Keāhole Point³.

Although Hualālai is not nearly as active as nearby Mauna Loa or Kīlauea, recent geologic mapping of the volcano shows that 80 percent of the mountain surface is covered by lava flows no older than about 5,000 years. In the past few decades, when most of the resorts, homes, and commercial buildings were built on the flanks of Hualālai, earthquake activity beneath the volcano has been low. In 1929, however, an intense swarm of earthquakes lasting more than a month was most likely caused by magma rising to near the surface. For these reasons, Hualālai is considered a potentially dangerous volcano that is likely to erupt again sometime in the next 100 years¹.

References

^ ^a ^b ^c ^d "Hualālai, Hawaiʻi's Third Active Volcano". USGS.
^ Macdonald, G.A.; A. T. Abbott (1970). Volcanoes in the Sea, Univ. of Hawaiʻi Press. pp. 441.
^ "Fishponds versus lavaflows". USGS (1997).

Hualalai.html

Contents

Structure

Recent eruptions

References

External links