Geology topics
Research about Hawai'i
Source-linked reports with geographic coverage including Hawai'i.
Natural hazards on the island of Hawaii
The island of Hawaii and the other islands of the Hawaiian chain are products of volcanic eruptions. Lava flows from hundreds of thousands of eruptions through countless centuries have built the Hawaiian Islands. Some volcanoes on the island of Hawaii have been very active during historic time, and similar activity is expected to continue throughout the foreseeable future.
Rockfall seismicity correlation with field observations, Makaopuhi Crater, Kilauea Volcano, Hawaii
During August 7-13, 1972, intense and sustained rockfall activity occurred in Makaopuhi Crater on the east-rift zone of Kilauea Volcano. In a 4-day period (August 7-10), approximately 270,000 m 3 of rockfall debris accumulated in Makaopuhi's west pit, representing a total kinetic energy release of about 101B ergs. Because the rockfalls happened within an area with an established seismic network, it was possible to correlate the seismic record of the rockfalls with onsite field observations. The seismic signatures of rockfalls are generally distinguishable from those of earthquakes and other recorded events. Approximate magnitudes determined for some of the largest rockfalls range from 0.8 to 1.2, corresponding to calculated seismic energy releases of 2X10 11 to 10X10 11 ergs, if the magnitude-energy relationship for earthquakes is applicable to rockfalls. The August 1972 swarms of rockfalls at Makaopuhi correlate in time not with moderate or large earthquakes but rather with local eruptive activity and are inferred to have been caused by eruption-induced modifications of stress patterns of the crater walls. However, the amount and nature of the stress change required to exceed the threshold stability of the crater wall and to trigger a rockfall flurry cannot be determined. The Makaopuhi activity is typical of most major rockfall episodes in other Kilauean pit craters in recent years, which also have been associated with volcanic activity, particularly during times of changes in eruptive behavior.
Potassium-argon ages and paleomagnetism of the Waianae and Koolau Volcanic Series, Oahu, Hawaii
Paleomagnetic and potassium-argon measurements on 786 oriented cores from 99 volcanic units at 18 sites in the Waianae and Koolau Ranges, Oahu, when combined with data from previous studies, show that the sub-aerial Waianae Volcano was active only from about 3.6 to 2.4 m.y. ago and the subaerial Koolau Volcano from about 2.6 to 1.8 m.y. ago. There is some evidence that Waianae Volcano was still active when Koolau Volcano emerged from the sea. The predominantly tholeiitic lower and middle members of the Waianae Volcanic Series are approximately contemporaneous and were extruded during the late Gilbert and early Gauss geomagnetic polarity epochs. They were followed within less than 0.2 m.y. by the alkalic lavas of the upper member, which were probably extruded largely during the later part of the Gauss normal polarity epoch. The Koolau Volcanic Series was extruded entirely during the early Matuyama reversed polarity epoch. Data from three thick stratigraphic sections in the Waianae and Koolau Volcanic Series indicate that stacks of lava flows as much as 470 m thick can be formed in less than 0.25 m.y. and that the maximum average period between superimposed lava flows is on the order of 103 yrs. Additional data on the hawaiite flow that led to the discovery of the Kaena reversed event indicate that this reversed flow is 2.85 ± 0.05 m.y. old. Angular dispersion of virtual geomagnetic poles (VGP) in the Hawaiian Islands appears to have decreased during the past 5 m.y. This may be caused by a decrease in dipole wobble, a decrease in the nondipole component of the Earth' magnetic field, or the accumulated effects of weathering, tectonism, and geomorphic processes in older rocks. The mean Waianae and Koolau VGPs are slightly on the side of the Earth's rotation axis away from Oahu. This supports, but does not prove, the hypothesis that the axial dipole is displaced slightly northward from the Earth's center. Three VGP “excursions” were recorded in sections of lava in the Waianae and Koolau ranges. During these excursions, the VGPs appear to have traveled away from or toward the geographic axis along great circle paths, suggesting they may be related to the dipole rather than the nondipole field and may record aborted reversals in polarity or rapid and infrequent dipole tilts.
Potassium-argon ages of lavas from the Hawi and Pololu Volcanic Series, Kohala Volcano, Hawaii: Reply
No abstract available.
Pahoehoe flows from the 1969–1971 Mauna Ulu eruption, Kilauea Volcano, Hawaii
Note: This paper is dedicated to Aaron and Elizabeth Waters on the occasion of Dr. Waters' retirement. Three types of chemically similar pahoehoe flows were observed to form during the 1969–1971 Mauna Ulu eruption. (1) A cavernous type called shelly pahoehoe, characterized by fragile gas cavities, small tubes, and buckled fragments of surface crust, was deposited when gas-charged lava welled out of the source fissure with little or no accompanying fountaining. (2) A comparatively smooth-surfaced, dense type, characterized by surface channels and only a few large cavities, formed from voluminous flows of partly degassed fallout away from the foot of lava fountains more than 100 m high. (3) A relatively dense type, characterized by hummocky surfaces with abundant low tumuli and overlapping pahoehoe toes and lobes, formed when largely degassed lava issued from tubes after flowing underground for several kilometers or more. Shelly pahoehoe is rarely found in the geologic record, but the other two types occur commonly. These three types of pahoehoe, which are completely intergradational, can be related qualitatively to the relative gas content and mode of flowage of the lava. The present surface of Kilauea is underlain mostly by hummocky, tube-fed pahoehoe.
Tragic base surge in 1790 at Kilauea Volcano
Reconstruction of events surrounding the deaths of a party of Hawaiian warriors in 1790 on Kilauea Volcano suggests that they were killed by a hot, relatively ash-free base surge. Recognition of structures attributable to base-surge deposition in deposits of the 1790 eruption is consistent with this reconstruction.
Relation of drainage problems to high ground-water levels, Coconut Grove area, Oahu, Hawaii
Purpose and Scope In 1969, hydrologic data-collection sites were established in and around the Coconut Grove area for the purpose of measuring directly the relationship between rainfall, runoff, ground-water levels, the level of water in Kawainui Swamp and the canals, and tidal fluctuations. The primary objective was to identify the causes of the occurrence and persistence of flooding and to gain data on which to base recommendations for remedial action. The scope of the study included establishing and operating flow and stage-recording gages on the Swamp, Kawainui Canal, and the inner canal; periodic and repeated measurements of ground-water level in test borings throughout the residential area; collection and analysis of soil and construction borings made for engineering purposes; the assembly and analysis of all available data relating surface and subsurface flow conditions, and the development of conclusions as to the causes and means to alleviate the flooding. This report summarizes the information collected from October 1969 to June 1971, includes analysis of the data, and discusses the probable causes of flooding.
Infrared surveys of Hawaiian volcanoes
Aerial infrared-sensor surveys of Kilauea volcano have depicted the areal extent and the relative intensity of abnormal thermal features in the caldera area of the volcano and along its associated rift zones. Many of these anomalies show correlation with visible steaming and reflect convective transfer of heat to the surface from subterranean sources. Structural details of the volcano, some not evident from surface observation, are also delineated by their thermal abnormalities. Several changes were observed in the patterns of infrared emission during the period of study; two such changes show correlation in location with subsequent eruptions, but the cause-and-effect relationship is uncertain. Thermal anomalies were also observed on the southwest flank of Mauna Loa; images of other volcanoes on the island of Hawaii, and of Haleakala on the island of Maui, revealed no thermal abnormalities. Approximately 25 large springs issuing into the ocean around the periphery of Hawaii have been detected. Infrared emission varies widely with surface texture and composition, suggesting that similar observations may have value for estimating surface conditions on the moon or planets.
Geologic map and guide of the island of Oahu, Hawaii
This bulletin, although designated Bulletin 2, is actually the fourth of a series published by the Division of Hydrography of the Territory of Hawaii. All four of the bulletins thus far published relate to the geology and ground-water resources of the island of Oahu.1 Together they present the results obtained on this island in the program of ground-water investigation of the Territory that has been conducted in cooperation with the Geological Survey, of the United States Department of the Interior. Bulletin 5 which is in preparation will describe the progress made in developing the ground-water resources of Oahu since Bulletin 1 was issued. In Bulletin 2 is presented the detailed geologic map of Oahu that has resulted from this investigation. The base for this map is the new topographic map of Oahu prepared by the Topographic Branch of the Geological Survey. This bulletin also contains a guide to the geology along the main highways, which can be used advantageously in connection with the geologic map. For 18 years the writer has had the great privilege of working under the technical direction of Mr. 0. E. Meinzer, geologist in charge of the Division of Ground Water, U. S. Geological Survey. Nearly two decades ago Mr. Meinzer envisioned the great benefits that the people of Hawaii would derive from a thorough study of the groundwater resources of these islands. He also recognized that a full knowledge of these resources could be obtained only by a complete understanding of the geology of the islands and the processes which formed them. This bulletin is one of a series that has been made possible largely as a result of his broad vision. Credit is due Mr. W. 0 . Clark for the location of all the dikes shown on plate 2 in the headwaters of Kamananui Stream near the north end of the Koolau Range, and to Dr. C. K. Wentworth for about a dozen dikes north of Kaimuki. Messrs. 0. E. Meinzer, G. R. Mansfield, M. H. Carson, G. A. Macdonald, and S. H. Elbert kindly criticized the manuscript. Mr. Harry L. Taeuber designed the cover and with James Y. Nitta prepared the illustrations. Their work has greatly enriched this bulletin. The topographic maps of 15-minute quadrangles, on a scale of 1 to 20,000 (approximately 3 inches to the mile), were used in the field as a base for the geologic mapping. The data were then transferred to the new topographic map of Oahu, which is on a scale of 1 to 62,500. The resulting geologic map is reproduced as plate 2 (in pocket) of this report. Some of the outcrops are too small to be shown on this smaller map. Plate 2 of this report was listed as plate 2 in Bulletin 1, which was, however, published without the map because of the time required to prepare and engrave the topographic base and the geologic map. The geologic structure sections at the bottom of plate 2 were not described in Bulletin 1, but are discussed below.