Report on Mauna Loa (United States) — November 1976
Natural Science Event Bulletin, vol. 1, no. 14 (November 1976)
Managing Editor: David Squires.
Mauna Loa (United States) Increased seismicity during 20-24 November
Please cite this report as:
Global Volcanism Program, 1976. Report on Mauna Loa (United States) (Squires, D., ed.). Natural Science Event Bulletin, 1:14. Smithsonian Institution.
19.475°N, 155.608°W; summit elev. 4170 m
All times are local (unless otherwise noted)
A substantial increase in the number of earthquakes beneath Mauna Loa was recorded 20-24 November (table 1). On the morning of 25 November, only one earthquake was recorded (beneath the NE rift). The USGS predicts a major eruption of Mauna Loa within the next 18 months.
|20 Nov 1976||350|
|21 Nov 1976||200-300|
|22 Nov 1976||200-300|
|23 Nov 1976||more than 300|
|24 Nov 1976||less than 100|
Geologic Background. Massive Mauna Loa shield volcano rises almost 9 km above the sea floor to form the world's largest active volcano. Flank eruptions are predominately from the lengthy NE and SW rift zones, and the summit is cut by the Mokuaweoweo caldera, which sits 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 basaltic shield volcano is covered by lavas less than 4000 years old (Lockwood and Lipman, 1987). During a 750-year eruptive period beginning about 1500 years ago, a series of voluminous overflows from a summit lava lake covered about one fourth of the volcano's surface. The ensuing 750-year period, from shortly after the formation of Mokuaweoweo caldera until the present, saw an additional quarter of the volcano covered with lava flows predominately from summit and NW rift zone vents.
Information Contacts: UPI