Introduction to Kīlauea and Mauna Loa volcanoes, Hawai`i

Pre-meeting field trip, August 11–12; max/min participants, 12/6

This 2-day trip provides an overview of Mauna Loa and Kīlauea, emphasizing new ideas about both volcanoes. The first day begins at Kīlauea summit with a discussion of the development of its caldera ca. 1500 CE, the ensuing 300 years of explosive eruptions, and effusive-explosive cycles of several centuries duration. Driving to the east rift zone, we walk through a forest of lava trees formed in July 1974, discuss the formation of the youngest pit crater on the rift zone (probably latest 19th century), and visit a portion of the Mauna Ulu eruptive fissure and its one-sided spatter rampart (May 24, 1969). A short walk into the Koa‘e fault system, a largely non-eruptive continuation of the east rift zone, reveals several meters of horizontal and vertical displacement in the past 700 y and enables a discussion of the relation between the fault system and the evolution of the east rift zone.

The second day focuses on the growth, evolution, and eruptive history of Mauna Loa, which encompasses more than half the Island of Hawai‘i and is the world’s largest volcano. We start in Hilo and traverse the island via the Saddle Road, visiting outcrops that provide a stratigraphic look at the growth of the NE flank of the volcano. Once in the saddle between Mauna Loa and Mauna Kea, we see lava flows from historical eruptions of 1984, 1935, 1899, 1880-81, 1855-56 and 1843. We explore the interaction of Mauna Loa with Mauna Kea and Hualālai volcanoes, discussing briefly the differences in evolution and eruptive history. Discussions will also include topics such as geologic hazards and risk.

Logistics:
The trip starts and ends at Hilo Hawaiian Hotel in Hilo on both days. We will travel in 7-passenger vans. Short walks but nothing strenuous. Participants should arrive in Hilo on August 10 and leave for Portland on August 13. We recommend staying at the Hilo Hawaiian Hotel, as this is where vans will meet each morning at 07:00. It is a short taxi ride from the airport. Be sure to fly to Hilo, not Kona!

Estimated Cost:
$50. Cost includes van rental, box lunches, water, National Park entrance fee on first day. All other costs (hotel, breakfast, dinner) are borne by the participant.

Leaders:
Don Swanson. U.S. Geological Survey
Frank Trusdell, U.S. Geological Survey
Don will lead the Kīlauea part of the trip, and Frank the Mauna Loa part.