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One of the most obvious questions regarding the June 27th Indeed, the high level of involvement with the community GSA TODAY | www.geosociety.org/gsatoday
flow is why it traveled no farther than 20 km from its source. may have helped to prevent the perception that HVO and the
For ‘a‘ā lava flows, a well-established relationship, governed by county were “crying wolf,” given that the crisis ultimately passed
flow cooling, exists between maximum flow length and effusion with little direct harm.These volcanological and sociological
rate (Walker, 1973). No such relation is known for pāhoehoe issues are the subject of a recently funded interdisciplinary
flows, however, because they frequently form insulating tubes, National Science Foundation Hazards SEES project with many
enabling them to travel much farther than would otherwise be collaborating institutions (including HVO). Developing new
possible (Keszthelyi, 1995; Kauahikaua et al., 1998, 2003). Long- tools based on the June 27th lava flow and similar experiences
lived pāhoehoe flows with 1–2 m3/s discharge rates, however, will be an important task for the next, inevitable, lava flow crisis,
represent a largely unknown low-effusion-rate end member whether in Hawai‘i or elsewhere in the world.
for that lava flow style.The June 27th flow’s low effusion rate,
coupled with cooling, crystal growth, loss of volatiles, lava tube ACKNOWLEDGMENTS
breakdown, and other factors, might indicate that—at 20 km
from its source—it had reached its maximum length for its We are grateful to the staff and officials of the County of Hawai‘i
effusion rate.The situation may be analogous to that of better- for their support and consistent collaboration on issues related to
modeled ‘a‘ā flows, but since long-lived, low-effusion-rate volcanic activity. In particular, we wish to acknowledge Hawai‘i County
pāhoehoe flows that are not limited in the extent they can travel Civil Defense Administrator Darryl Oliveira, Mayor Billy Kenoi, and
(by the ocean, for example) are nearly unknown in nature, the their staffs. Pilot David Okita was, as always, masterful and tireless
June 27th flow represents a key example that should be the basis in conducting flights to aid in monitoring and research activities. Our
of future modeling. frequent coworkers from the University of Hawai‘i (both the Hilo
and Mānoa campuses), including professors and students, provided
Finally, the infiltration of lava into and downslope movement important assistance in tracking the June 27th lava flow over time and
within existing ground cracks has not previously been observed evaluating hazards (Ken Hon and Cheryl Gansecki were especially close
to the extent seen at Kīlauea during August and September collaborators), and HVO greatly benefits from the many volunteers, like
2014. Lava disappeared from the surface for several days at a Ben Gaddis and David Dow, who assist with field, laboratory, and office
time. Small plumes of condensed steam coming from the forest work. Our thanks to Cynthia Gardner and two anonymous reviewers for
were the only visible indication of flow advancement (Fig. 3B), their comments, which greatly improved the manuscript.
although crack opening was indicated by nearby borehole
tiltmeter and GPS instruments.The flow of lava through existing REFERENCES CITED
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