Report on Mauna Loa (United States) — 17 August-23 August 2005
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
17 August-23 August 2005
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2005. Report on Mauna Loa (United States). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 17 August-23 August 2005. Smithsonian Institution and US Geological Survey.
19.475°N, 155.608°W; summit elev. 4170 m
All times are local (unless otherwise noted)
HVO reported on 21 August that extension across Mauna Loa's summit had resumed over the previous few weeks after pausing for much of July. Seismicity remained at low levels at the volcano.
Geological Summary. Massive Mauna Loa is a basaltic shield volcano that rises almost 9 km from the ocean floor to form the world's largest Holocene volcano. Flank eruptions typically occur from the lengthy NE and SW rift zones, and from the Moku'aweoweo summit is caldera, which is within an older and larger 6 x 8 km caldera. Two of the youngest large debris avalanches documented in Hawaii traveled nearly 100 km from Mauna Loa; the second of the Alika avalanches was emplaced about 105,000 years ago (Moore et al., 1989). Almost 90% of the surface of the volcano is covered by lavas less than 4,000 years old (Lockwood and Lipman, 1987). Beginning about 1,500 years ago, a series of voluminous overflows from a summit lava lake covered about 25% of the volcano's surface. Over the last 750 years, from shortly after the formation of Moku'aweoweo caldera until the present, an additional 25% of the volcano has been covered with lava flows, mainly from summit and NW rift zone vents.
Source: US Geological Survey Hawaiian Volcano Observatory (HVO)