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GSA TODAY | FEBRUARY 2016  Michael Poland, U.S. Geological Survey Cascades Volcano               Kīlauea’s outbreak was noteworthy for its potential
                           Observatory, Vancouver, Washington 98683, USA; mpoland@usgs         (and uncertain) impact and long months of anticipation by
                           .gov; Tim R. Orr, James P. Kauahikaua, Steven R. Brantley, Janet    communities at risk. Had the flow extended far enough along
                           L. Babb, Matthew R. Patrick, Christina A. Neal, Kyle R. Anderson*,  the path it was following, it would have crossed a highway used
                           Loren Antolik, Matthew Burgess, Tamar Elias, Steven Fuke,           by thousands of vehicles each day; isolated a portion of the
                           Pauline Fukunaga, Ingrid A. Johanson, Marian Kagimoto, Kevan        island that is home to nearly 10,000 residents (Callis, 2014); cut
                           Kamibayashi, Lopaka Lee, Asta Miklius, William Million, Cyril       power, water, and other infrastructure on which those residents
                           Moniz, Paul G. Okubo, A. Jeff Sutton, T. Jane Takahashi, Wes A.     depend; and overrun homes in multiple communities.The flow
                           Thelen**, William Tollett, and Frank A. Trusdell, U.S. Geological   stalled repeatedly within several hundred meters of the highway,
                           Survey Hawaiian Volcano Observatory, Hawai‘i National Park,         destroying only one house before breakouts ~15 km upslope
                           Hawai‘i 96718, USA                                                  in March 2015 diverted lava away from the front.The activity
                                                                                               provided new information about the behavior of pāhoehoe lava
                           ABSTRACT                                                            flows, as well as lessons about communicating information to
                                                                                               the public during a prolonged crisis.Although the 2014–2015
                             Lava flow crises are nothing new on the Island of Hawai‘i,        crisis has passed, the lava flow remains active and could threaten
                           where their destructive force has been demonstrated repeatedly      communities in the future.
                           over the past several hundred years.The 2014–2015 Pāhoa lava
                           flow crisis, however, was unique in terms of its societal impact    SETTING THE STAGE
                           and volcanological characteristics. Despite low effusion rates, a
                           long-lived lava flow whose extent reached 20 km (the longest at       Kīlauea, one of the most active volcanoes in the world, has
                           Kīlauea Volcano in the past several hundred years) was poised       erupted almost continuously from East Rift Zone (ERZ) vents
                           for months to impact thousands of people, although direct           since 1983 and from a vent at the summit (which hosts an active
                           impacts were ultimately minor (thus far). Careful observation       lava lake) since 2008 (Orr et al., 2015a; Patrick et al., 2015a) 	
                           of the flow reaffirmed and expanded knowledge of the                (Fig. 1).The current ERZ eruption has extruded more than 4 km3
                           processes associated with pāhoehoe emplacement, including           of lava, covering more than 142 km2 of land (updated from Orr
                           the direct correlation between summit pressurization and            et al., 2015a). Such a large amount of lava has had a significant
                           flow advance, the influence of existing geologic structures on      impact on island residents, destroying 215 primary structures as
                           flow pathways, and the possible relationship between effusion       of 2015, including nearly all of the village of Kalapana in 1990.
                           rate and flow length. Communicating uncertainty associated          Roads and other infrastructure have also been covered, and vog
                           with lava flow hazards was a challenge throughout the crisis,       (volcanic smog) has impacted the health of people, animals, and
                           but online distribution of information and direct contact with      agricultural products across the island.
                           residents proved to be effective strategies for keeping the public
                           informed and educated about flow progress and how lava flows          Pu‘u ‘Ō‘ō, a cinder cone and lava shield, is the dominant vent
                           work (including forecasting limitations).Volcanological and         for the ongoing ERZ eruption, although other vents within a few
                           sociological lessons will be important for inevitable future lava   kilometers uprift and downrift have also been active. Following
                           flow crises in Hawai‘i and, potentially, elsewhere in the world.    an uprift fissure eruption in March 2011, lava slowly filled the
                                                                                               crater of Pu‘u ‘Ō‘ō until September 2011, when a small fissure
                           INTRODUCTION                                                        eruption on the east flank of the cone fed the informally named
                                                                                               Peace Day lava flow.  A lava tube system developed, and within
                             Basaltic lava flows were very much in the news in 2014. In        weeks, lava flowed southeast from the vent more than 10 km
                           August of that year, Bárðarbunga erupted in Iceland, eventually     to the Pacific Ocean (Orr et al., 2015a).While this behavior is
                           extruding more than a cubic kilometer during six months of          common for the current ERZ eruption, the lava discharge rate
                           activity (Gíslason et al., 2015). Pico do Fogo in the Cape Verde    for the Peace Day flow was low (1–2 m3/s), which is about half the
                           islands began erupting in November, sending out lava flows that     average rate measured since 1983 (Poland, 2014).
                           overran two villages and displaced ~1,000 people (González
                           et al., 2015).And in June 2014, an outbreak of lava at Kīlauea        The eruption remained relatively stable until January 2013,
                           Volcano sent flows toward communities in the Puna District on       when lava overtopped the crater of Pu‘u ‘Ō‘ō and spread to
                           the east side of the Island of Hawai‘i (Fig. 1).                    the northeast.The new flows, informally named the Kahauale‘a
                                                                                               flows (Patrick et al., 2015b), gradually became dominant, and the
                                                                                               Peace Day flow ceased activity by November 2013.The northeast
                                                                                               trajectory of the Kahauale‘a flows was significant because of the

                              GSA Today, v. 26, no. 2, doi: 10.1130/GSATG262A.1.

                              * Now at U.S. Geological Survey California Volcano Observatory, Menlo Park, California 94025, USA.
                              ** Now at U.S. Geological Survey Cascades Volcano Observatory, Vancouver, Washington 98683, USA.

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