Active Crater Research Articles

Soils and Micro-organisms from Mount Erebus, Antarctica

WHILE conducting pedological and biological studies in the ice-free areas of East Antarctica, one of us (F. C. U.) and Dr. H. Janetschek had the opportunity in February 1962 to climb Mount Erebus. Considered the only active volcano known in Antarctica, Mount Erebus (3,721 m) consists of trachyte, kenyte, basalt and other volcanic rocks1. Extensive ice and snow cover limits the soil occurrence to the lower snow-free slopes, to exposed rock projections, a few areas near the hot fumaroles, and in the vicinity of the active crater.

Volcanothermal Investigation of Active Crater : Temperature variation in the bottom ground of the Naka-dáke crater of the Aso volcano

Volcanothermal Investigation of Active Crater : Temperature variation in the bottom ground of the Naka-dáke crater of the Aso volcano

Volcanic activity in Costa Rica and Nicaragua in 1954

The volcanic activity in Costa Rica in 1954 was limited chiefly to Irazú and Poás volcanoes, although fumarolic activity was reported at Rincon de la Vieja. The activity of Irazú is entirely fumarolic and of about the same intensity as in previous years. Volcano Poás, which had maintained a geyser‐like activity from a lake which filled the bottom of the active crater for many years, began a new eruption in March or April, 1953. This, which appears to be a major eruption, is continuing with a large gas column frequently visible from San Jose' and some fresh ash, cinders, and scoria on the upper slopes of the active cone. The volcanic activity in Nicaragua was limited to the following vents: (1) Concepción has been in a mild state of activity since 1948. The explosions, which sent out a cloud of gas, occur at intervals of about 30 minutes. (2) Santiago, which has been in a vigorous state of fumarolic activity since 1947, is continuing with some increase in the volume of gas and a corresponding increase in the area in which vegetation is being damaged. (3) Momotombo exhibited fumarolic activity at the summit crater in about the same intensity as in previous years. (4) Las Pilas began fumarolic activity in October, 1952, which has increased steadily in volume. The activity is localized along a fracture near the summit. (5) Cerro Negro contains some active furnaroles in the summit crater. (6) Telica has vigorous fumarolic activity in the summit crater in about the same intensity as in previous years. (7) El Viejo is reported to have some furnaroles in the crater but none were observed in a flight over it in a small plane.

Empirical studies of some of the seismic phenomena of Hawaii*

Summary and Conclusions A comparison was made of all the periods of local earthquakes entered in the record books, and this showed that the P wave of 0.3-sec. period occurred a maximum of 156 times, and a secondary peak for the period of 0.5 sec. occurred 89 times. The S wave of 0.5-sec. period had a maximum of 129 occurrences, and a secondary peak for 0.8-sec. period had 100. This suggested that in any earthquake the ratio of the period of the S to the P wave was inversely as their velocities, or as the square root of three. The maxima just given appear to hold for such waves from all depths of origin. It had been noted previously that large amplitudes and periods occur together. The upper limits of the amplitudes of the P and S waves of local shocks were found to vary with the cube of the periods. Different results were found for the variation of epicentral shocks in California and Japan. The difference may be caused by the difference in physical characteristics of the underlying crustal rock. While these studies in Hawaii were made on shocks of intensities I to IV, Rossi-Forel, they show promise of giving information about the waves to be expected in destructive earthquakes. The sectorial lines may be raised by new data, but in each region should approach some unknown lines as a limit. Formulas were used to correct the observed waves to those of standard displacement and consequent period. These periods were plotted with respect to distance and depth, with no reliable result. A tendency was shown for the period of P waves to increase with distance more rapidly than the period of S waves, whereas observations of more distant earthquakes would suggest the opposite. Study of the ratios of the amplitudes of the P to the S wave (AP/SS) showed no distance effect. The formulas from the previous amplitude-period study suggest that this ratio should not vary with the local distance. For Hawaii the ratio averages about 15 per cent. About 60 per cent of the foci are less than 5 km. deep, 70 per cent less than 10 km. deep. Very few appear to have originated at 60 or more km. depth. The decline in numbers of earthquakes with depth is a rapidly decreasing exponential function. Most of the deep earthquakes are under Mauna Loa and the Kilauea southeast rift zone. A large number of the located shallow foci are in and near the Kilauea crater. Possibly this is an increase that should be expected near any active volcanic crater, but it may be due to the close network of stations about Kilauea crater. The magnitude of the shock is not a function of the location either areally or in depth; that is, large earthquakes may be expected in any part of the island and near-by sea bottom and at all depths to at least 60 km. A method of classifying the earthquake records is based on the number of P or S waves shown on the seismogram, which indicate the key number from one to seven. A map of Hawaii was constructed showing the areas in which the different types of shock had originated. The first type, K-1, occurs either central to Mauna Loa or within 50 to 60 km. radius of the seismograph. Type K-2 is not recorded from northwest Hawaii. Type K-3 does not occur close to the instruments. Types K-4 to K-7 are noted to occur at somewhat greater distances, and to date have been observed only from small outlying areas. Earthquake records of simple character are generally near the area of deep-focus shocks and near the seismographs, so that the waves come in at a steep angle. Earthquakes under Kilauea crater are generally simple. As the foci become more distant and shallow they also become more complicated in type. These criteria should help in designating phases and consequent locations, but they are not final, and may be of no help beyond 100 km. The number of phases in some of the records of outlying earthquakes suggest a complexity of structure in the island mass and the near-by sea bottom. The locations near and on the extension of rifts and in pronounced lines and zones suggest a larger and more numerous system of rifts than has previously been mapped. The resulting pattern of rifts about Mauna Loa is roughly an asterisk. The main accent is on the visible active rifts to the southwest and the east-northeast of Mokuaweoweo. These rifts have apparently controlled most of the island's seismicity in the immediate past.

General Features and Glacial Geology of Mauna Kea, Hawaii

Research Article| December 01, 1937 General Features and Glacial Geology of Mauna Kea, Hawaii HERBERT E. GREGORY; HERBERT E. GREGORY Search for other works by this author on: GSW Google Scholar CHESTER K. WENTWORTH CHESTER K. WENTWORTH Search for other works by this author on: GSW Google Scholar GSA Bulletin (1937) 48 (12): 1719–1742. https://doi.org/10.1130/GSAB-48-1719 Article history received: 04 Aug 1937 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation HERBERT E. GREGORY, CHESTER K. WENTWORTH; General Features and Glacial Geology of Mauna Kea, Hawaii. GSA Bulletin 1937;; 48 (12): 1719–1742. doi: https://doi.org/10.1130/GSAB-48-1719 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract INTRODUCTIONThe four volcanic masses whose coalescing bases form the island of Hawaii are substantially alike in petrographie composition; all of them bear cinder cones on their flanks, and lava flows from all of them have extended far into the sea, and also inland to join their neighbors. As regards their topographic expression, they form two groups. Mauna Loa and Hualalai have remarkably flat, smooth profiles and summit craters; Mauna Kea and Kohala are rugged masses sharply incised by canyons and have no topographic feature to indicate the major source of the materials of which they are constructed. The two giant domes, Mauna Loa and Mauna Kea, reveal these differences clearly.The profile of Mauna Loa extends from the coast as an almost unbroken curve with a gradient averaging about 600 feet to the mile nearly to the rim of the active crater, Mokuaweoweo, at an altitude of 13,680 feet.1 . . . This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

A Naturalistic Model of Kilauea Volcano, Hawaii

There has recently been placed on exhibition in the Geological Section of the Harvard University Museum a large and remarkably naturalistic model of Kilauea, the active crater on the eastern slope of Mauna Loa, the great volcano on the island of Hawaii. It is the work of Mr. George Carroll Curtis of Boston and embodies the ripe fruition of his many years of effort in the production of relief models that are true to nature. In some respects a study of this model will give to the student a clearer understanding of the great crater than he could obtain from pictures, descriptions, or even a visit to Kilauea itself.

The Taal Volcano

THE latest publication received from the Weather Bureau of the Philippines is entirely devoted to a yiolent eruption of the Taal Volcano, which took place on January 30 of this year. This volcano, which lies thirty miles south of Manila, is represented by a crater in a small island which rises from the centre of Lake Bombon. As this lake joins Taal in its activities it also must be regarded as an active crater. If its waters could be removed by the deepening of the channel of the river which now drains it, we should have a replica of Mount Aso, in South Japan, viz., a large crater about twelve miles in diameter with an active cone in its centre. The craters of these two mountains rank among the largest of which our world can boast, but they are by no means comparable with the largest in the moon. If, however, the crater plains of Taal and Aso could be lowered to the level on which these mountains grew, they would closely resemble many lunar volcanoes.