|
Eruptive History of Mauna Loa Volcano,
Hawai'i
The colors represent historical
eruption flow data up to the present.
Source 15
The Last Major Eruption:
1984
March 25, 1984 - April 15, 1984
Volume of lava produced: 2.2 x 108 m3
Central vent and radial fissure eruptions with lava
flows at Moku`aweoweo and SW and NE rift zones
Map of a`a flows from the 1984 eruption. The lava
was unable to reach the major town of Hilo.
Source
22
Three years prior to the 1984 eruption, earthquakes
began and increased in number and magnitude. Some
of the major seismic events leading to the eruption
included an earthquake swarm 5 to 13 kilometers below
the volcano in September 1983 and a 6.6 magnitude
earthquake 15 kilometers southeast of the peak at the
Ka`oiki fault system in November 1983. Leading up
to the major eruption in March, lower magnitude but
still significant earthquakes increased in their
frequency. A brief eruption at the summit in 1975
began a period of inflation around this area until the
eruption in 1984. Just before the eruption
occurred, a series of indicators took place. Not
only did the number of the low magnitude earthquakes
increase to a rate of 2-3 per minute; volcanic
tremors were also recorded at Moku`aweoweo. At
11:30 p.m. the day before the eruption, a tremor began,
and by 1 a.m., the tremor amplitude increased a
significant amount. At 1:25 a.m. the eruption was
underway. Eruptive fissures went down the
southwest rift zone and northeast portion of
Moku`aweoweo (flows A and B on the map).
From March 26 to 29, fast-moving a`a flows advanced in
the direction towards Hilo (flow E), and other
slower flows were headed to Kulani Prison (flow D).
As seen in the map, the flows heading towards the prison
stopped with 3.2 kilometers to go, and did not succeed
in crossing Powerline road. The advancing flow
burned vegetation and caused explosions from methane gas
on its way to Hilo. On March 29, a levee broke out
(flow F) causing flow E to dwindle. On
April 5, another levee broke out (flow G).
More viscous lava and a decrease in the rate and amount
of lava erupted slowed the flows down by causing more
frequent levee collapses and channel blocks, which in
turn prevented more lava from feeding the flow fronts.
The flows did not reach Hilo because of the vegetation
it had to go through, the low temperature and therefore
high viscosity of the lava, gentle slopes, and the
decline in eruption rate. The 1984 eruption ended
on April 15.
Source 22
The Last 100 Years
A dated
layout on the island of each specific historic Mauna Loa flow
since 1843.
Source
11
July 5, 1975 - July 6, 1975
Volume of lava produced: 3 x 107 m3
Central vent and radial fissure eruptions with lava
flows at Moku`aweoweo and SW and NE rift zones
June 1, 1950 - June 23, 1950
Volume of lava produced: 3.8 x 108 m3
Radial fissure and explosive eruptions and lava flows
from SW rift zone that caused property damage
January 6, 1949 - May 31, 1949
Volume of lava produced: 1.2 x 108 m3
Central vent, radial fissure, and explosive eruptions at
Moku`aweoweo and SW rift zone, formed lava flows
April 26, 1942 - May 10, 1942
Volume of lava produced: 1.8 x 108 m3
Central vent, radial fissure, and explosive eruptions at
Moku`aweoweo and NE rift zone, formed lava flows
April 7, 1940 - August 18, 1940
Volume of lava produced: 1.1 x 108 m3
Central vent, radial fissure, and explosive eruptions at
Moku`aweoweo and SW rift zone, formed lava flows
November 21, 1935 - January 2, 1936
Volume of lava produced: 8.7 x 107 m3
Central vent and radial fissure eruptions at Moku`aweoweo
and NE rift zone, formed lava flows and property damage
December 2, 1933 - December 18, 1933
Volume of lava produced: 1 x 108 m3
Central vent and radial fissure eruptions at Moku`aweoweo,
formed lava flows
April 10, 1926 - April 28, 1926
Volume of lava produced: 1.2 x 108 m3
Radial fissure eruption at SW rift zone that formed lava
flows and caused property damage
September 26, 1919 - November 5, 1919
Volume of lava produced: 1.8 x 108 m3
Radial fissure eruption at SW rift zone that formed lava
flows and caused property damage
May 19, 1916 - May 30, 1916
Volume of lava produced: 3.1 x 107 m3
Radial fissure eruption at SW rift zone that formed lava
flows and caused property damage
November 25, 1914 - January 11,1915
Volume of lava produced: 5.5 x 107 m3
Central vent eruption at Moku`aweoweo that formed lava
flows
January 9, 1907 - January 24, 1907
Volume of lava produced: 1.2 x 108 m3
Central vent and radial fissure eruptions at SW rift
zone and Moku`aweoweo that formed lava flows and caused
property damage
Source 1
|