Page 5 - gt1602
P. 5
Highway 130 0 4 8 km N
Island of Hawai‘i Pāhoa Figure 1. Map of the eastern portion of Kīlauea
KH Volcano, which comprises the Puna District of
Kīlauea East Rift Zone Ground the Island of Hawai‘i. Red dot in caldera gives
Caldera cracks 30 June 2014 location of 2008–present eruptive vent. GPS
29 July 2014 stations indicated by white circles and tiltmeter
Pu‘u ‘Ō‘ō 2 km 29 Aug. 2014 by white triangle. East Rift Zone noted by
29 Sept. 2014 white dashed line, with Pu‘u ‘Ō‘ō eruptive
1983–2013 flows vent labeled and lava flows from 1983 to 2015
2013–2014 Kahauale‘a flows colored as gray—1983–2013; pink—2013–2014
2014–2015 June 27th flow Kahauale‘a lava flows; red—2014–2015 June
Paths of steepest descent 27th lava flow (as of 5 Aug. 2015). Pāhoa and
Kaohe Homesteads (“KH”) are labeled, as is
30 Oct. 2014 Highway 130 connecting Pāhoa and nearby
29 Nov. 2014 communities to the rest of the island. Black
30 Dec. 2014 lines are roads, with thicker lines indicating
10 Mar. 2015 more heavily used roads. Denser groupings
5 Aug. 2015 of roads occur in subdivisions. Blue lines are
paths of steepest descent based on analysis of
topography. Area of heavily cracked ground
occurs between labeled arrows. Lower right
gives zoom of the June 27th flow, with colors
indicating flow extent over time.
Pacific Ocean
population downslope in the island’s lower Puna District the “June 27th lava flow,” as it was informally called, advanced
(Fig. 1). Pu‘u ‘Ō‘ō lies at the topographic crest of the ERZ, so quickly along a narrow front to the east-northeast (Fig. 1).The
the direction that lava travels is dependent on the location from flow emerged from near the base of Pu‘u ‘Ō‘ō, ~50 m lower
which lava is extruded. Lava that erupts from the south side than the source of the Kahauale‘a flows, and drainage of magma
of Pu‘u ‘Ō‘ō flows south toward the ocean, whereas lava that contributed to early high effusion rates and rapid flow-front
erupts from the north side flows northeast toward residential advance.
and commercial areas (Patrick et al., 2015b) (Fig. 1).
Lava reached ~4.5 km from the vent over the ensuing month,
Puna is a zone of high lava flow hazard due to frequent developing a lava tube system to feed the distal part of the
inundation during the past several hundred years (Kauahikaua flow.The floor of Pu‘u ‘Ō‘ō subsided throughout this period as
and Tilling, 2014). In 2007, a northeast-directed flow caused
concern because, had it followed the most likely path of 0.08
steepest descent, it would eventually have imperiled downslope
communities (Kauahikaua, 2007); however, after a few 0.06
months, a breakout at the vent directed lava to the south and
stopped the northeast advance.Although no such change in Distance change (m)
direction occurred in 2013, the low–effusion-rate conditions
that characterized the Peace Day flow persisted, and lava never GSA TODAY | www.geosociety.org/gsatoday
advanced more than 9 km from Pu‘u ‘Ō‘ō through mid-2014 0.04 Summit
(Patrick et al., 2015b).
0.02
THE JUNE 27TH LAVA FLOW
0
The first indication of an impending change in activity at
Kīlauea was the onset of sustained inflation at the volcano’s -0.02 Pu‘u ‘Ō‘ō
summit and at Pu‘u ‘Ō‘ō in late May 2014 (Fig. 2). Inflation -0.04
indicates increasing pressure within the volcano’s magmatic
system and often precedes intrusions and the formation of -0.06
new eruptive vents (e.g., Orr et al., 2015a).The pressurization
culminated on 27 June 2014, when new fractures opened on the -0.08
northeast flank of Pu‘u ‘Ō‘ō (Fig. 3A).This new vent system J F MAMJ J ASOND
diverted lava from the Kahauale‘a flows, which ceased all
activity soon after (Patrick et al., 2015b).The initial pulse of 2014
Figure 2. Distance change between continuous GPS stations spanning
Kīlauea’s summit (black) and Pu‘u ‘Ō‘ō (blue) during 2014. Positive change is
generally indicative of inflation and negative, deflation. Red line marks 27 June
2014. Station locations are given in Figure 1.
5
