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NUHOU KANAKA PUKA Summer 2018 Inside this issue… The Spring and Summer 2018 Eruption of Kīlauea .............................................. 1 Message from the Outgoing and Incoming Department Chairs .............. 11 Degrees, Awards & Honors ................. 13 2017-2018 GG Faculty Research & The Spring and Summer 2018 Eruption of Kīlauea Teaching Highlights ............................. 15 In case you hadn’t heard, Kīlauea has dominated the geologic Distinguished Alumnus ....................... 23 Alumni News ....................................... 25 news for the past few weeks. G&G students and faculty, past and Field Trips ............................................ 33 present, are involved with monitoring and studying this Donation ............................................. 37 fascinating, but sadly, very destructive event. Most of the G&G ‘ohana has followed along with fascination thanks to webcams and Nuhou Kanaka Puka detailed timely reports, images, and data from the Hawaiian Nuhou Kanaka Puka (“Alumni News” Volcano Observatory (HVO), as well as with information from in Hawaiian) is published by the others on social media. HVO has an on-line chronology that is Department of Geology and updated daily (or more frequently when necessary) here, and Geophysics of the School of Ocean KHPR (Hawai‘i Public Radio) has their own until July 2, with even and Earth Science and Technology (SOEST) for its alumni and friends. more details and links here. In these chronologies (as well as that which follows), keep in mind that there are essentially two This issue is published in an simultaneous eruptions: 1) earthquakes, ground fractures, and electronic only format. eruptions in the lower East Rift Zone (ERZ); and 2) earthquakes, subsidence, and draining of the magma chamber up at the summit About Us (Figure 1). Writing a chronology that keeps track of these two Chair: Paul Wessel areas is difficult enough – imagine monitoring them both. Editors: Gregory Moore If you had tuned in at the end of April, the GG Relations & In the beginning: Honors Committee Kīlauea news featured a month or so of dwindling lava flows from Pu‘u ‘Ō‘ō. Rising lava levels in Pu‘u ‘Ō‘ō and at Halema‘uma‘u Department of Geology & Geophysics prompted HVO to issue a warning that new flows might break out School of Ocean & Earth Science & of the Pu‘u ‘Ō‘ō edifice, posing potential hazards to anyone hiking Technology (illegally) nearby. New flows could also eventually threaten University of Hawai‘i, Mānoa 1680 East-West Road, POST 701 different downslope areas of the volcano, as happened in 2014- Honolulu, Hawaii 96822 2015 at Pāhoa. Instead, on the afternoon of April 30, all the lava P (808) 956-7640, F (808) 956-5512 stored within the Pu‘u ‘Ō‘ō edifice as well as in the shallow storage Email : [email protected] system beneath drained down into the ERZ plumbing system. A Website : day later (May 1), summit tiltmeters recorded a switch from http://www.soest.hawaii.edu/GG/ Facebook : inflation to deflation. On May 2 the surface of the lava lake in https://www.facebook.com/UHGeolGeophys Halema‘uma‘u began to drop. (continued on next page) 1 Fig. 1: Shaded relief image of Kīlauea summit and ERZ, showing locations mentioned in this article. Magma migration to Leilani Estates: Over the striking parallel to the rift zone. Initially the cracks next few days magma moved downrift from Pu‘u were cold, but by May 3 steam began to issue from ‘Ō‘ō, traceable via migrating seismicity, and HVO some of those in the southern set and at around 5 issued a notice that an eruption somewhere along pm that afternoon the first gas and spatter erupted the ERZ was a possibility. Preliminary InSAR and GPS from what became vent 1. Over the next 20 hours results by Bridget Smith-Konter, Lauren Ward, and vents 2-6 opened, both uprift and downrift of vent Liliane Burkhard (working with Xiaohua Xu and 1. Samples of the lava and spatter were analyzed by David Sandwell of UCSD; Figure 2) showed that the UH-Hilo geochemist Cheryl Ganseki, using new migrating magma produced at least 0.25 m of rapid-analysis techniques, and they were found to subsidence at Pu‘u ‘Ō‘ō and as much as 0.15 m of not match the composition of Pu‘u ‘Ō‘ō lava. uplift farther downrift, and the pattern is very Instead, it was “old” magma that had been stored complex. Seismicity began to concentrate under within the rift zone, perhaps for decades. At public Leilani Estates subdivision, which sits in a shallow meetings soon after, HVO staff noted that the graben along the ERZ, about 2.5 km SE of Pāhoa and pattern of old magma being pushed out of the rift ~20 km downrift of Pu‘u ‘Ō‘ō. Many of the zone prior to the arrival of “fresh” magma had been earthquakes were so shallow that they were observed during previous ERZ eruptions. The public audible, and on May 2 cracks in roads were and media were therefore aware of the possibility discovered within Leilani Estates. These cracks were that hotter more voluminous fountains and flows concentrated along two sets ~900 m apart, both might erupt in the future. For a brief while, non- 2 Fig. 2: InSAR-derived line-of-sight (LOS) ground deformation between April 20 and May 2 (i.e., encompassing the collapse of Pu‘u ‘Ō‘ō and beginning of dike emplacement into the lower ERZ). The satellite was looking from the WSW; ground surfaces that moved away (to the east and/or down) are shown in blue, and areas that moved toward (to the west and/or up) are shown in red. The ground motion contour interval is 50 mm; these values are the component of true motion projected onto the line of sight, and therefore minimum values. The radar incidence angle for this acquisition was 42.7° meaning that if vertical ground motion is assumed, the displacement values (positive or negative) can be multiplied by ~1.4. geochemists and even normal people were motion took place deeper, on the basal décollement discussing evolved magmas with high Zr between Kīlauea and the old ocean floor. concentrations. Preliminary InSAR and GPS results by Smith-Konter’s team plus G&G alumnus James Foster (HIGP) The May 4 Mw 6.9 earthquake: In addition to the indicate that much of Kīlauea’s south flank moved numerous small earthquakes within and near Leilani oceanward by as much as 0.75 m. The earthquake Estates, larger volcano-tectonic quakes occurred on generated a small tsunami along the SE coastline of May 3 and 4. The largest of these occurred at 12:32 Hawai‘i (40 cm at the now-buried-by-lava tide pm on May 4, with a moment magnitude (Mw) of 6.9 station in Kapoho) and shook loose a dramatic and an intensity of VI along the S coast of Hawai‘i (it plume of reddish oxidized dust from Pu‘u ‘Ō‘ō. was felt by many people in POST). Its epicenter was just offshore and ~12 km SSW of Leilani Estates Early flows in Leilani Estates: Meanwhile in (Figure 3). According to the National Earthquake Leilani Estates, ground cracks continued to extend Information Center the earthquake was a thrust as far uprift as HWY 130 and as far downrift as event with a preliminary focal depth of 2.1 km on a Pohoiki Rd. By May 6, 12 of these cracks had plane striking 240º and dipping 20° inland. G&G erupted spatter and/or lava, but only vent 8 alumnus Nathan Becker, at the Pacific Tsunami generated a significant flow, which sadly, destroyed Warning Center, noted that although the initial about 20 homes in the afternoon and evening of break was shallow and corresponds to a shallow May 6. Bruce Houghton spoke movingly of thrust fault within the outer bench (identified by encountering Leilani Estates residents who had lost G&G alumnus Denise Hills and former SOEST Young everything they owned. By May 9, vents 13, 14, and Investigator Julie Morgan in 2002), the bulk of the 15 opened, extending the eruption just outside (in a 3 Fig. 3: GPS motion vectors (yellow), InSAR LOS motion, and preliminary estimate of ruptured fault plane for the May 4 2018 Mw 6.9 earthquake (red star). This was a low-angle thrust event with uplift inferred offshore. The largest offset was ~75 cm measured at station KAEP, on the coast. LOS motion also suggests significant horizontal SE- directed motion. downrift direction) Leilani Estates and into a eruption when (as had long been thought to have subdivision called Lanipuni Gardens. Vent 15 was been the case) a long-lived lava lake dropped low the first to erupt a composition dominated by enough to interact explosively with the water table. “fresh” Pu‘u ‘Ō‘ō magma, but it did not produce On the morning of May 9 HVO issued a public significant fountaining or flows. announcement that due to the continued dropping of the Halema‘uma‘u lava lake, there was a The pre-eruption slopes dictated that lava possibility that hydromagmatic explosions might erupted within Leilani Estates would flow NE, exit occur. Half an hour later a landslide into the (now the subdivision, and continue NE, constrained to the very deep) lava lake triggered an explosion which SE by a row of old scoria cones. Lava from the many interpreted to be the first such downrift parts of the vent system (i.e. outside of hydromagmatic event, although it was not. That Leilani Estates), however, would head either NE evening, during a public presentation at Hawai‘i along the S side of these same old cones or S and SE Volcanoes National Park, HVO scientists forecasted toward the coast into the ‘Opihikao/Pohoiki area, that at the current rate of lake-level drop (2.2 m hr- potentially threatening a large area of scattered 1), it should reach the depth of the water table (~400 homes and farms.