John Lockwood - Academia.edu (original) (raw)

Papers by John Lockwood

Aerial view of some of the prominent fissures within the southwest rift zone of Kïlauea Volcano. ... more Aerial view of some of the prominent fissures within the southwest rift zone of Kïlauea Volcano. The dark lava erupted from these fissures in September 1971. (Photograph by J.D. Griggs.

Da~hed lines arc boundaries between volcanoes.

Professional Paper, 1975

Modal compositions and specific gravities were determined for 329 samples of granitic rocks of th... more Modal compositions and specific gravities were determined for 329 samples of granitic rocks of the Mount Abbot quadrangle, California, and 23 selected granitic, volcanic, and metamorphic rocks were chemically and spectrographically analyzed. Modal data and specific gravities plotted on simplified geologic maps supplement the published geologic map of the quadrangle. Most of these data, except for specific gravities, do not show syst ematic, contourable variation within plutons. The largest pluton within the quadrangle, occupying an area of about 100 mi 2 (260 km 2) , is the highly porphyritic quartz monzonite of Mono Recesses. Alkali feldspar megacrysts are concentrated near the borders of the pluton. Megacrysts also increase in abundance with increasing elevation, which may indicate that the roof 0f this pluton was originally not too far above present erosional levels. Specific gravities and chemical analyses of samples show that the pluton is weakly wned, with the densest and most basic rocks located along the highly porphyritic borders. A plot of megacryst abundance versus matrix alkali feldspar content shows an irregular but generally inverse relation between the two, indicating that total alkali feldspar abundance was not the controlling factor in the growth of giant (up to 8 em) megacrysts. The concentration of megacrysts in the more basic, marginal areas of the pluton indicates either that the bulk composition of the granodiorite magma was appropriate for growth of giant alkali feldspar megacrysts in these areas or that processes especially conducive to their growth operated near pluton borders.

Professional Paper, 1999

Three brief eruptions-the longest lasting 3 days, the shortest only 6 hours-took place in the sum... more Three brief eruptions-the longest lasting 3 days, the shortest only 6 hours-took place in the summit region of Kilauea Volcano during the last half of 1974: July 19-22, September 19, and December 31. These eruptions followed an inferred constriction of the upper East Rift Zone (ERZ) supply conduits to the long-lived Mauna Ulu eruption in early 1974, causing magma and excess pressure to accumulate beneath Kilauea's summit. The 1974 eruptions each shifted farther westward across Kilauea's summit, reflecting the apparent westward migration of magmatic storage, from the upper ERZ (Mauna Ulu), across Kilauea's summit caldera, and eventually down the volcano's southwest flank. Subsurface migration of magma storage centers across Kilauea is documented not only by the loci of eruptive activity, but also by seismic and geodetic observations, which clearly trace the westward propagation of magma-generated seismic activity and deformation centers. These eruptions occurred during a period of increasing unrest at neighboring Mauna Loa Volcano, a factor possibly related to tectonic processes that also influenced the 1974 Kilauea summit eruptions. The July eruption was fed by separate, subparallel fissures that bridged the zone between the upper ERZ and the southeastern margin of the modern Kilauea Caldera. These lavas, characterized by bimodal compositions, erupted from separate vent systems and in part represented the eruption of stored, "old" magma that was forced to the surface by an intrusion of more primitive magma from depth. The highly differentiated lavas from the southern vent system are characterized by megascopic plagioclase phenocrysts, a rarity at Kilauea's summit. Lavas erupted in September are much more homogeneous than those erupted in July, but only slightly more mafic than the mean composition of the two groups of July lavas combined. The December lavas, however, include some of the most mafic compositions erupted at Kilauea's summit since 1959 (12.2-15.6 percent MgO) and may include compositions little modified from a batch of "new" magma 1 THE 1974 SUMMIT ERUPTIONS OF KlLAUEA VOLCANO, HAWAI'I study should the Pu'u 'O'o eruption cease, eruptions return to Kllauea's summit, and then activity resume at Mauna Loa.

Professional Paper, 1976

More than 400 samples of plutonic rocks were collected during the geologic mapping of the Shaver ... more More than 400 samples of plutonic rocks were collected during the geologic mapping of the Shaver Lake quadrangle. Of these, 368 samples were modally analyzed, and the volume percentages of quartz, potassium feldspar, plagioclase, and mafic minerals and the bulk specific gravities are plotted, and partly contoured where the data permit, separately on a simplified geologic base map. Quartz, potassium feldspar, and plagioclase, calculated to 100 percent, are plotted on triangular diagrams. Chemical and spectrographic analyses of 32 plutonic rocks and 3 volcanic rocks are tabulated, and normative quartz, orthoclase, and plagioclase (albite plus anorthite) are plotted on a triangular diagram. Data on the ages determined by the potassium-argon and uranium-lead methods for some plutonic and volcanic rocks are tabulated. A map of conspicuous, steeply dipping joints is included.

Ground deformation associated with the 1975 magnitude-7.2 earthquake and resulting changes in activity of Kilauea Volcano, Hawaii

Professional Paper, 1985

Radiocarbon, 1989

Twenty-eight 14C analyses are reported for carbonized roots and other plant material collected fr... more Twenty-eight 14C analyses are reported for carbonized roots and other plant material collected from beneath 15 prehistoric lava flows erupted from the northeast rift zone (NERZ) of Mauna Loa Volcano (ML) utilizing the recovery techniques of Lockwood and Lipman (1980). Most samples were collected from the Hilo 7 1/2’ quadrangle during field work for a geologic map of that quadrangle (Buchanan-Banks, unpub data); a few sample sites are located in adjacent quadrangles: Piihonua to the west and Mountain View to the south. Altitudes are given in English units as well as metric to facilitate locating sites on USGS topographic maps.

Journal of Volcanology and Geothermal Research, 1980

Extensive faulting and cracking along the east rift zone preceded, accompanied, and followed the ... more Extensive faulting and cracking along the east rift zone preceded, accompanied, and followed the flank eruptive phase. New faults having as much as 20 feet of vertical displacement were formed, and many old faults were reactivated. The 1961 flank activity occurred a:long the north side of the rift zone, which is noticeably bipartite; the north side is characterized by gra• benhorst topography and the south side, by cinder cones.

Journal of Geophysical Research: Solid Earth, 1988

The weathering of Hawaiian basalts in arid and semiarid environments is accompanied by change in ... more The weathering of Hawaiian basalts in arid and semiarid environments is accompanied by change in their thermal infrared emittance spectra. The spectral differences can be measured and mapped with multispectral imaging systems. The differences appear to be related to the degree of development, preservation, and alteration of glassy crusts; the oxidation of iron; and the accretion of silica‐rich surface veneers. Because the measurements are quantitative and in image format, they are useful for estimating relative ages in geologic mapping of lava flows. In Hawaii this technique is most diagnostic for distinguishing among sparsely vegetated flows less than 1.5 ka in age.

Bulletin Volcanologique, 1980

Field studies in Hawaii aimed at providing a radiocarbon-based chronology of prehistoric eruptive... more Field studies in Hawaii aimed at providing a radiocarbon-based chronology of prehistoric eruptive activity have led to a good understanding of the processes that govern the formation and preservation of charcoal beneath basaltic lava flows. Charcoal formation is a rate-dependent process controlled primarily by temperature and duration of heating, as well as by moisture content, density, and size of original woody material. Charcoal will form wherever wood buried by lava is raised to sufficiently high temperatures, but owing to the availability of oxygen it is commonly burned to ash soon after formation. Wherever oxygen circulation is sufficiently restricted, however, charcoal will be preserved, but where atmospheric oxygen circulates freely, charcoal will only be preserved at lower temperature, below that required for charcoal ignition or catalytic oxidation. These factors cause carbonized wood, especially that derived from living roots, to be commonly preserved beneath all parts of pahoehoe flows (where oxygen circulation is restricted), but only under margins of aa. Pratical guidelines are given for the recovery of datable charcoal beneath pahoehoe and aa. Although based on Hawaiian basaltic flows, the guidelines should be applicable to other areas.

Radiocarbon, 1978

This list contains the results of some measurements made between 1966 and 1975, and includes some... more This list contains the results of some measurements made between 1966 and 1975, and includes some earlier unpublished dates. Samples are counted in the form of acetylene gas, as previously, and ages computed on the basis of the Libby half-life, 5568 ± 30 years. The dates have not been corrected for fractionation by making a 13C measurement. The error listed, always larger than the one-sigma statistical counting error commonly used, takes into account possible fractionation in the laboratory and in nature and variability experienced with replicate samples. We thank Linda Wilt for helping in the preparation of the manuscript and Charles Oman for his technical assistance.

Scientific Investigations Map, 2019

Scientific Investigations Map, 2017

The Geometry of Loko Kuapā Kīholo: the regional significance and cultural context of a Royal Hawaiian Fishpond

Journal of Pacific Archaeology, Feb 1, 2014

Kīholo fishpond is located on the north-west coast of Hawai`i Island. In 1859, less than fifty y... more Kīholo fishpond is located on the north-west coast of Hawai`i Island. In 1859, less than fifty years after its construction, the artificial pond was inundated by a voluminous Mauna Loa lava flow and only small remnants of the original bounding wall remain. Historical accounts of its original scale are ambiguous and incomplete. In this paper we describe newly-discovered, lava-surrounded remnants of the wall that allow an estimate the fishpond’s original size. An analysis of the fishpond is presented in order to weight its potential function within the Hawaiian food economy against its place in elite status competition. We reconstruct the original pond’s configuration using a combination of geomorphological evidence, flow surface features, archaeological analogy and inference. We then calculate the labor required to have constructed the fishpond and, with the help of historical fisheries data, provide an estimate of the potential production. This empirically grounded input – output relationship is then evaluated in terms of the political, economic and ecological variables relevant to the development of political complexity in Hawai`i. We conclude that the pond lacked an efficient short-term subsistence function. The results suggest that large royal fishponds should be considered in terms sometimes reserved for monumental architecture. We conclude that large fishponds, in contrast to complex but incrementally constructed dry land agricultural works, played significant symbolic roles in wealth-displays and in elite status competition.

Applications of GIS to the estimation of lava flow hazards on Mauna Loa Volcano, Hawai'i

Mauna Loa Revealed: Structure, Composition, History, and Hazards, 1995

Journal of Volcanology and Geothermal Research, 2005

Anatahan island is 9.5 km east-west by 3.5 km north-south and truncated by an elongate caldera 5 ... more Anatahan island is 9.5 km east-west by 3.5 km north-south and truncated by an elongate caldera 5 km east-west by 2.5 km north-south. A steep-walled pit crater~1 km across and~200 m deep occupies the eastern part of the caldera. The island is the summit region of a mostly submarine stratovolcano. The oldest subaerial rocks (stage 1) are exposed low on the outer flanks and in the caldera walls. These include thick (~10 m) and thin (2-3 m) lava flows, well-indurated tuffs, and scoria units that make up the bulk of the island. Rock compositions range from basaltic andesite to dacite, and most are plagioclase-phyric. On the steep north and south flanks of the volcano, these rocks are cut by numerous east-west-oriented, few-hundred-m-long lineaments of undetermined origin. Indurated breccias unconformably overlie scarps cut into stage 1 units low on the south flank. Intermediate-age eruptive units (stage 2) include caldera-filling lava flows and pyroclastic deposits and, on the outer flanks, vents and valley-filling lava flows. The youngest pre-2003 volcanic unit on Anatahan (stage 3) is a hydromagmatic surge and fall deposit rich in accretionary lapilli. Prior to 2003, this unit was found over almost the entire island, and in many places original depositional surfaces and outcrops could be found in high-energy environments along the coast, indicating a young (but undetermined) age. During reconnaissance visits in 1990, 1992, 1994, and 2001, geothermal activity (fumaroles as well as pits with boiling, sediment-laden pools) was observed in the southern part of the pit crater. In March and April 1990, increased local seismicity, a large regional earthquake, and reported increased fumarolic activity in the pit crater prompted evacuation of Anatahan village, at the west end of the island. Our first field investigation took place in late April 1990 to assess the level of volcanic unrest, conduct reconnaissance geological observations, collect rock and geothermal water samples, and set up a geophysical monitoring network. Results at this time were inconclusive with

Scientific Investigations Map, 2020

Photograph showing the Nīnole Hills-the oldest rocks found at the surface of Mauna Loa. The flat-... more Photograph showing the Nīnole Hills-the oldest rocks found at the surface of Mauna Loa. The flat-topped hill in the center is Makanau. The Nīnole Hills range in age from 227,000 to 108,000 years. The ʻaʻā flow in the foreground is the Keāpōhina flow, dated at 1,100 years before present.