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The magma eruption rates of Merapi volcano form 1890 to 1992 are re-examined chronologically. For this volcano, movements of extruded lavas and domes as well as their extrusions are important because they control the modes of the subsequent activities and cause nuees ardentes and lahars. The monthly eruption rates varied widely, but the cumulative volume of lavas has increased linearly and is expressed as 0.1x106 m3/month. The magma production rate of this volcano may have been constant for these 100 years. Recurrent excessive effusion of lavas is tentatively interpreted by assuming a magma reservoir. The averaged eruption rate is small in comparison with other volcanoes such as Nyramuragia, Kilauea and Vesuvio. However, it is remarkable that the activity has been continuous for these 100 years and the total amount of lava discharged during this period reached more than 108 m3. A simple model for the formation of the 1992 lava dome is presented. The viscosity of the lavas is probably between 106 and 107 P and the length of the magma conduit is probably less than 10 km.

This study was designed to explore the role of Factor I in the release of immune complexes (IC) from human erythrocytes (E). The interactions between E and IC constructed with murine monoclonal antibodies were examined using, as a complement source, autologous plasma, plasma depleted of Factor I by > 90%, or Factor I-depleted plasma reconstituted with purified Factor I. Striking differences were observed in the interactions between E and different types of IC in Factor I-depleted plasma. The release of IC constructed with IgG1, IgG3, IgM or IgA antibodies was abolished by Factor I depletion whereas IC containing IgG2a or IgG2b antibodies were still released from E in Factor I-depleted plasma. Moreover, when IC containing IgG2a antibodies were incubated briefly in Factor I-depleted plasma, under conditions in which the IC were bound but not released, and then resuspended in the presence or absence of Factor I, as little as 5% of the normal physiologic level of Factor I released the IC from E. Thus, IC containing IgG2a antibodies appear to be exquisitely susceptible to release from E by Factor I. Additional differences in the susceptibility of IC containing IgG1, IgG3, IgM or IgA antibodies to release from E were revealed when Factor I-depleted plasma was reconstituted with Factor I. Under these conditions, the relative susceptibility of IC to release was: IC containing IgG1 or IgA antibodies > IC containing IgM antibodies > IC constructed with IgG3 antibodies. While isotype was critical in determining susceptibility to release, some clonotypic differences between isotype-matched pairs of IC were also evident. Differences in IC release from E by Factor I may reflect antibody matrix-mediated differential susceptibility of IC-bound C3b and/or C4b to cleavage by Factor I and may have implications for immunoregulation, host effector cell mechanisms and the pathophysiology of IC diseases.

We report two cases of basal cell epithelioma (BCE) on the vulva.Case 1: A57-year-old woman noticed itching tumor on the right of her lavium majus for one and half year. Histopathologically a diagnosis of BCE (solid type) was made.Case 2: A 60-year-old woman noticed painful tumor on the right of her lavium majus for two years. Histopathologically a diagnosis of BCE (solid and superficial type) was made.Clinical and statistical study of 48 patients with BCE seen at Department of Dermatology, Nippon Medical School Second Hospital during 10 years from 1984 to 1994was reported.No sex differences were seen. The age of the patients at the time of the first medical examination ranged from 29 to 88 years and the age peak was in the 6th decade. More than 70% cases arose on the head, face and neck. Most common sizes of the tumors were less than 2cm in diameter. In clinically, our cases consisted of 72% of noduloulcevative type of BCE and 28% of super ficial type.In histopathologically, solid type of BCE was most frequent, and more than 70% cases were diagnosed solid and mixed type. Recurrences were seen in 2 cases, though no metastasis was seen.

Male Sprague-Dawley rats were fed a 0.1% ethionine-added choline-deficient diet for 8 weeks to induce liver cirrhosis. At the same time 100 mg/kg/day teprenone was administered orally in order to evaluate its effects on the liver and gastric mucosal blood flow. Blood flow increased not only in gastric mucosa but also in liver tissues in the teprenone group. Serum transaminase levels and histopathologic findings of the liver also improved. These findings suggest that teprenone alleviates hepatocellular injuries. This effect may be partly attributable to cytoprotective effects of the catenoid isoprenoid moiety of teprenone on liver cells.

Campi Flegrei is a unique volcanic region located near Naples, Italy. Anomalous crustal movements at Pozzuoli in Campi Flegrei have been documented since the Roman period. The movements were gradual and have continued to the present, occasionally accompanying swarms of local earthquakes and volcanic eruptions. Generally the movements proceed with low seismicity. After the 1538 eruption of Monte Nuovo, Pozzuoli had subsided monotonously, but it changed to uplift abruptly in 1969. The uplift accelerated in 1983 and 1984 reaching more than 2 m, and thereafter began to subside. Many discussions of this event have been published. In Japan, we have examples of deformations similar to those at Campi Flegrei, mainly in volcanic areas, and rarely in non-volcanic areas. The former includes Iwojima, Miyakejima and Aira caldera while the latter is represented by Cape Omaezaki. Iwojima is a volcano island, and its secular uplifts since the 18th century are recognized as an unusual event. Miyakejima volcano and Aira caldera exhibited anomalous movements with low seismicity after their eruptions. Cape Omaezaki is not situated in volcanic zone but near a subduction zone, and gradually and continuously subsides as a precursor to a large earthquake. In such cases as Campi Flegrei and the Japanese localities, we would question whether the deformations are accompanied by normal seismicity or low seismicity. To examine quantitatively the relationship between seismicity and related deformation, seismic efficiency is generally useful. The crustal deformations in all the regions cited above are characterized by exceptionally low seismic efficiencies. In the present paper, the deformations at Pozzuoli and Iwojima are mainly described and a comparative discussion among these and other localities in Japan is supplemented. It is concluded that such anomalous phenomena in volcanic areas are attributable to peculiar rheological aspects of the material composing the local upper crust, and the deformation in a non-volcanic area is of tectonic origin.

Wage increases, along with job tenure, are one of the most robust empirical regularities found in labor economics. Several theories explain these empirical regularities, and such theories offer sharp empirical predictions for the relation between productivity-tenure and wage-tenure profiles. The human capital model, with cost and benefit sharing between workers and employers, predicts a steeper productivity-tenure profile than wage-tenure profile. The matching quality model predicts that the two profiles will overlap. Theories that involve the information asymmetry between employers and employees predict a steeper wage-tenure profile than productivity-tenure profile to induce workers' effort and enhance efficiency. This paper estimates the productivity-tenure profile and the wage-tenure profile by estimating the plant-level production function and the wage equation using employer-employee matched data from Japan. These estimations offer a comprehensive test for the relative applicability of the two theories on the wage-tenure profile. Estimation results indicate a steeper wage-tenure profile than productivity-tenure profile and point to the relative importance of the deferred wage payment contract.

Diverging economic inequality has become a common focus of economic debate in developed countries. In particular, the recent experience of Japan has started attracting international attention. We take advantage of a rich micro-level data set from the Basic Survey on Wage Structure (1989-2003) to perform an in-depth analysis of the change in the inequality and distribution of the hourly wage. We observe that lower returns to education and years of tenure contribute to diminishing income disparity between groups for both sexes. A larger variance within a group contributes to the wage disparity for males, while an increased heterogeneity of workers' attributes contributes to the wage disparity for females. The Dinardo, Fortin, and Lemieux decomposition also confirms the basic findings from a parametric variance decomposition.

What happened to the traditional, long-term employment practices in Japan after the 1990s has remained unexplored. We take advantage of a micro data set from the Basic Survey on Wage Structure to provide new evidence regarding the years of tenure for Japanese male workers after a decade-long recession. While the practice of long-term employment is still alive among the workers who are already in the system, the proportion of workers who are not covered by the system has increased. These ongoing phenomena contribute to the bipolarization in the Japanese labor market.

Pozzuoli is located at the center of the Campi Flegrei caldera, near Naples and is famous for its anomalous subsidence and upheaval documented since the Roman period. Its secular and gradual subsidence can be interpreted as self-loading compaction of the caldera fills while abrupt upheavals are geologically suspected to be caused by magmagenic movements or steam forces. In order to interpret the origin and the process of the Pozzuoli upheavals, they are compared with active volcanisms represented by the 1977-1982 eruption of Usu volcano in Hokkaido. Usu volcano outburst in 1977 in major pumice eruptions and repeated magmatic and phreatomagmatic eruptions, and manifested remarkable ground deformations accompanying earthquake swarms. In 1969, the ground of Pozzuoli began to upheave with increases in seismicity but finally failed to cause any eruptive phenomena at the surface; nevertheless there are common characteristics of their motives and processes between the two events. The motive of the Usu deformation is clearly due to magma movements while that of the Pozzuoli upheaval has not been completely settled. A quantitative relationship between seismicity and deformation gives a clue for discussing the motive of the Pozzuoli deformations. The discharge rates of seismic energy and the deformation rates are compared between the two events and a certain similarity is found. This suggests that the origin of the Pozzuoli event may be partly magmatic as well as the Usu eruption, but its behavior largely depends on the property of the caldera deposits. When their deformation volumes are taken into consideration, their characteristics become quantitatively conspicuous. The ground at Pozzuoli is much more easily deformed by the upward motive force than Usu volcano. This is due to the rheological property of the caldera deposits of Campi Flegrei, and agrees to the theory that interprets the secular subsidence observed in historical times, as self-loading compaction. It is interesting that there is a point of contact between anomalous movements of the ground along the seashore in Italy and remarkable magmatic movements at the active volcano in Japan.

In the discussion of lava dome formation, viscosity of magma plays an important role. Measurements of viscosity of magmas in field and laboratory are briefly summarized. The types of lava dome emplacements are classified into two, squeeze- and spine-type, by kinetic processes. The squeeze-type is the formation of a dome as a result of squeezes of magma through conduits and the latter is solidified magma forced to ascend by underlying fluid magma. An important parameter in the formation of such lava domes is their growth rates. Lava domes of squeeze-type are governed by the Hagen-Poiseuille Law which involves their viscosoties and other eruption parameters. At present, the real viscosity of magmas at the site of lava dome is still inaccessible. In order to avoid uncertainty in viscosity of magmas, a conception of «macroscopic viscosity» is proposed, which involves effects of chemical components, mainly SiO2 and volatile material, crystals and temperature, and their changes with time. Lava dome formations during the 20th century are briefly examined and their growth rates are estimated. The relationship between the growth rates and the SiO2 content of the magma is statistically studied, and the macroscopic viscosity is empirically expressed as a function of SiO2 content. The linearity between the two parameters is reasonably interpreted. This means that formation processes of lava domes are dominantly controlled by macroscopic viscosity of magma.

The formation of the two particular lava domes in Hokkaido, Japan is described and interpreted mainly from geophysical viewpoints. The 1909 eruption of Tarumai volcano was not violent but produced a lava dome over four days. The growth rate of the dome is discussed under the assumption that the lava flow was viscous and plastic fluid during its effusion. By Hagen-Poiseuille?s Law, the length of the conduit of the lava dome is rather ambiguously determined as a function of viscosity of the magma and diameter of the conduit. The 1944 Usu dome extruded as a parasitic cone of Usu volcano, not in the crater, but in a flat cornfield at the foot of the volcano. From the beginning to the end for more than 17 months, seismometric and geodetic observations of the dome activity were carried out by several pioneering geophysicists. Utilizing their data, pseudo growth curves of the dome at each stage can be drawn. The lava ascended rather uniformly, causing uplift of the ground surface until half-solidified lava reached the surface six months after the deformation began. Thereafter, the lava dome added lateral displacements and finally achieved its onion structure. These two lava domes are of contrasting character, one is andesitic and formed quickly while the other is dacitic and formed slowly, but both of them behaved as viscous and plastic flows during effusion. It is concluded that both the lava domes formed by uplift of magma forced to flow through the conduits, analogous to squeezing toothpaste out of a tube.

In order to study the roles of vasoactive peptides during tissue repair of gastric ulcers, we compared concentrations in tissue surrounding gastric ulcers of endothelin-1(ET-1), adrenomedullin (AM), and transforming growth factor-beta (TGF-beta) among different stages of ulcer development. A total of 82 cases were studied. Ulcers were located in the gastric angulus in 51 cases. All cases were positive for Helicobacter pylori (Hp). Ten cases were in the active stage (GA), 18 were in the healing stage (GH), and 28 were in the scarring stage (GS). As control, 17 cases of Hp-positive gastritis (gast+) and 14 of Hp-negative gastritis (gast-) were studied. The concentrations of endothelin (ET) and TGF-beta were in the order of GH> GA> GS, and those of AM were in the order of GS > GH > GA. On immunostaining, ET stained positively in endothelial cells and vascular smooth muscle cells (VSMCs) during the GH and GS stages, and AM stained positively in histiocytes during GA, GH and GS, and also stained positively in glandular epithelia and smooth muscle fibers during GH and GS. When our results were reviewed with respect to the regulation of vascular tonus and the proliferation of VSMCs, ET and AM were considered to have roles in the regulation of proliferation.

Atherosclerotic changes in the coronary artery are exacerbated by the balance between LDL, which carries cholesterol into the arterial wall, and HDL, which carries it out from the wall. The molecular weight of LDL is about 2 x 10(6) and that of HDL is about 4 x 10(5), which is almost 1/5 of the molecular weight of LDL. For this reason, LDL/HDL x 5 should be a good indicator of coronary heart disease. We evaluated this index in two subject groups. At first, we determined whether it could predict the incidence of effort angina in participants of a medical examination system. Most of the subjects were healthy and good candidates for primary prevention. LDL/HDL x 5 was a more sensitive index predicting effort angina than total cholesterol, LDL or HDL. The concentrations of HDL were significantly lower in myocardial infarction patients at all ages in both sexes. The average serum concentration of HDL was 56.6 +/- 15.0 mg/dl in the medical examination group and 38.9 +/- 12.2 mg/dl in the AMI group. We tested whether our new index, LDL/HDL x 5, could predict the incidence of re-infarction in patients with myocardial infarction who were candidates for secondary prevention. LDL/HDL x 5 was a more sensitive index predicting re-infarction than total cholesterol, LDL or HDL.

We investigated the relationship between microcirculatory disturbance and the host response to Helicobacter pylori infections in gastric ulcer scars to determine the role of endothelin-l (ET) in ulcer recurrence. The subjects were divided into three groups. The GuS group consisted of patients who had red scarring (S1 stage) at the gastric angle with H. pylori, the gast+ group who had gastritis with H. pylori, and the gast- group who had gastritis without H. pylori. During endoscopic examination. biopsies were taken from the gastric angle. Mucosal ET, nitric oxide (NO), interleukin-8 (IL-8), and RANTES were measured. ET, inducible NO synthase (iNOS), and endothelial constitutive NOS (ecNOS) were immunostained. Mucosal ET and oxides of nitrogen (NOx) were significantly higher in the GuS group than in the other groups. IL-8 was elevated in the GuS and gast+ groups, and RANTES was elevated in the gast+ group (p < 0.01). There was prominent inflammatory cell infiltration in the GuS group. ET-positive cells were found in vascular smooth muscle, gastric epithelium, and gastric smooth muscle. iNOS-positive cells were found in vascular smooth muscle, gastric epithelium, gastric smooth muscle, and inflammatory cells. In conclusion, local inflammation and microcirculatory disturbance persist at the center of the ulcer scar (S1). Decreased cytokine levels and increased ET and NO (mainly synthesized by iNOS) levels suggested that microcirculatory disturbance is a more important factor than immune response in ulcer recurrence.

Taal Volcano is peculiar in its violent explosivity in spite of its low altitude. The surrounding topographies suggest that the origin of Taal Volcano is either a caldera or a graben structure. To confirm the caldera origin one must search for a vast quantity of caldera ejecta balancing with the depression. As a first step, a gravity survey was carried out on and around Taal Volcano, and high gravity anomalies were lound on Volcano Island. The distribution of the gravities may suggest a graben structure overlying a denser layer of igneous material.

Analysis of ground-deformation data obtained at and around Sakurajima volcano during the 1914 eruption indicates that the deformation may be interpreted by assuming a model with two pressure sources, one shallow (about 2 km deep) and vertically directive and the other deep (about 8 km deep) and obliquely, directly beneath the volcano. This model is reasonable from the viewpoint of the volcanic processes. The local upheaval near the centers of eruption has scarcely recovered because it surpassed the elastic limit. The recovery of the regional depression after the eruption can be interpreted as pressure accumulation beneath the volcano. It may be concluded that the center of pressure would remain at the deeper source beneath the volcano, but that the pressure would change, resulting in surface deformation. The depression and its recovery suggest the presence of a pressure focus or a ‘magma reservoir’ beneath the volcano.

Two models of pressure source to interpret the crustal deformations associated with volcanic activities are discussed by example. It is pointed that the magma pressure causing the crust to be deformed may sometimes trigger remarkable tectonic earthquakes around volcanoes.

東京女子医大,成人医学センターの定期検診受診者1,391名および同消化器内科に肝疾患のため入院した発端者20名(急性肝炎8名,慢性肝炎6名,肝硬変3名,肝癌3名)の家族90名を対象としHBs抗原およびHBs抗体についてsubtypeを中心に検討を加えた.定期検診受診者の抗原陽性看は1.4%,抗体陽性者は27.4%であり,肝疾患患看家系では抗原陽性者は41.1%,抗体陽性者は34.4%で定期検診受診者より明らかに高率であり,特に抗原の陽性率が高い.subtypeでは定期検診受診者,肝疾患患者家系とも抗原はadr,抗体はRが優位であり,定期検診受診者で6ヵ月間隔で2度施行できたものでsubtypeの変動したものはなかった.肝疾患患者家系では肝硬変,肝癌群に兄弟,子供に抗原,抗体の集積がみられ,subtypeでは抗原がadwの家系は急性肝炎の1例のみで,他は抗原はadr,抗体はRであり,同一家族内でsubtypeの異なるものはなかった.

Microgravity measurements and levelling surveys on volcanoes are not always easy to make, but are useful for studying volcanic processes quantitatively. Gravity changes associated with volcanic activity are not always significant. Precision of microgravity measurements depend critically on the procedures adopted, and those applied in the present paper are described. Levelling technique is now orthodox, and some empirical laws relating ground deformation to volcanic activity are deduced from the accumulated data. Gravity changes occur at the same time and places as ground deformations. The relationship between microgravity and height changes are discussed from the standpoint of analyzing the data obtained on volcanoes. The observational results obtained on four volcanoes in Japan are separately analyzed because each volcano exhibits different patterns of gravity changes and deformations. During the 1977–1982 activity of Usu volcano, deformation was accompanied by microgravity changes frequently observed at a particular benchmark at the base of the volcano for about five years. The gravity changes prove to be not a direct effect of magma movements but to be caused by the deformations of ground strata and aquifers around the benchmark. The 1983 eruption of Miyakejima volcano was associated with local gravity changes around the eruptive fissures due to magma intrusion which was approximately modelled. Similarly the 1986 eruption of Ooshima volcano caused gravity changes on the volcano, but these were poorly correlated with elevation changes and their origins were not uniquely interpreted. To detect gravity changes associated with the activity of Sakurajima volcano, an equigravity point was selected at the north of the volcano besides the gravity points on and around the volcano itself. The probable gradual accumulation of magmas beneath the volcano for eight years is substantiated by observed microgravity and elevation changes.

Seismic energy release during the precursory, eruptive and declining stages of volcanic activities provides various information about the mechanisms of volcanic eruptions and the temporary developments of their activities. Hitherto the energy release patterns from precursory earthquake swarms were used to predict the eruption times, especially of andesitic or dacitic volcanoes. In this paper the discussion is expanded to quantify the total amount of seismic energy released at the threshold of volcanic eruptions, with reference to the results observed at several volcanoes. The results generally indicate that the cumulative seismic energy release from the precursory earthquake swarms exceed 1017∼18ergs before eruptions at any andesitic or dacitic volvanoes. This allows the seismic efficiency, or the ratio of energy radiated seismically, and the energy required for the volumetric expansion to be estimated by incorporating available deformation data with the seismic data. The dependency of seismic efficiency on the type of volcanic activity, i. e. non-explosive outbreaks, phreatic and magmatic eruptions, dome formation, etc., was evaluated from observations at a few volcanoes that provided a variety of examples.

Accumulation of a huge amount of welded tuff and subsequent formation of calderas are typical examples of volcanisms on a large scale. Crustal structures which are related to the phenomena may be a key for the study of volcanisms on the earth. In Japan there are some 10 calderas of low gravity anomaly type, large and small in diameter, and accordingly in volume of their ejecta, welded tuff. The low gravity anomalies are very characteristic inside the calderas and just concentric with their rims, and are due to mass deficiency caused by eruptions of a huge amount of ejecta. The author (1957), hitherto, has clarified the subterranean structures resulting from the caldera formations by a gravimetric method. In this paper, the author describes the crustal structures beneath Sikotu Caldera in Hokkaido, Japan, deduced from the gravimetric, geomagnetic, seismic and geologic surveys. And referring several examples of the subterranean structures of the other calderas in Japan, the author wishes to discuss the crustal structures that would produce the caldera formations.

This is to summarize the writers' studies on the anomalous behavior of geomagnetic variations in Japan which were published in a series of papers in the Bulletin of the Earthquake Research Institute [1]. An anomalously large amplitude of the vertical component of geomagnetic variations is pointed out at Hermanus, S. A., and some observatories in Japan. The distribution especially in Japan is statistically examined. The anomaly is found in a limited area in the central part of Japan. The results of the analysis based on the potential theory show that the anomaly is caused by the magnetic field originating in the earth. The anomaly is well approximated by an apparent magnetic dipole situated under central Japan. But it still remains unknown why such a localized anomaly occurs on occasions of geomagnetic variation.

The subsurface structure of Oosima Volcano is discussed mainly from the geophysical standpoints on the basis of the available data. First the author summarizes the results of gravimetric surveys and explosion-seismic observations carried out on and around Oosima Island to discuss the deeper structure of the volcano and then proceeds to a discussion of the caldera structure utilyzing the results of the drillings, electric prospecting and gravity measurements. Finally a tentative model of the shallow subsurface structure of Oosima Volcano is presented.

At Oosima Volcano, Izu, various geomagnetic studies have been continued since its great eruption of 1950-51. And also the results of geophysical and geological investiga-tions of the structure of Oosima Volcano have been accumulated. In 1957, the present author discussed the anomalous change in geomagnetic field observed in the 1953-54 eruption. In the present paper the author would revise this discussion reflecting upon the results of 10 years' observation of magnetic declination and the accumulated re-sults of the subsurface structure of the volcano. The conclusion is that the observed anomalous changes are interpretable by the possible thermal processes beneath the volcano. Its quantitative results on heat supply to the volcano may lend a sugges-tion as to energetics of volcanisms.

Geomagnetic works have been conducted on Volcano Mihara since its great eruption in 1950. As a result of repeated magnetic surveys marked changes in the geomagnetic field have been found. A continuous recording also proves the occurrence of anomalous changes in geomagnetic declination in connection with development and subsidence of the volcanic activity. It seems likely that the main parts of the geomagnetic changes thus found are caused by the demagnetization and magnetization within the volcano, which is composed of basaltic rocks containing a large amount of magnetite. Geomagnetic studies will be useful for inferring the internal state of certain volcanoes and sometimes even for the prediction of their eruptions.

A gravimeter survey was made on the frozen surface of the gigantic caldera lake, Kuttyaro. A Gravity low, reaching -46 milligals, was found, with iso-anomaly contour lines conforming the caldera shape. A layer of coarse pumice thickening toward the centre is required to account for the observed anomalies. This is compatible with volcanological inferences. Gravity anomaly distributions at several other calderas are discussed also.

Crustal deformations, accompanied by eruptions of both basaltic and andesitic volcanoes, have proved surprisingly systematic. In 1958, K. MOGI presented a model of pressure source of explosive or implosive types beneath volcanoes in order to interpret the deforma-tions observed at Sakurazima and in Hawaii. In the present paper, an alternative model with pressure sources of thrust tpye is proposed and proves to be applicable to the observations.

Observations and reductions of the gravimeter survey on Volcano Huzi are fully described. The survey was accompanied by various inevitable difficulties but the accuracy of calculating the Bouguer anomalies is kept high enough to bear volcanological discussion. The results are rather suggestive to the theory of caldera-formation. Comparison with the gravity anomaly on the volcanic islands in the middle of the ocean is also made.

Usu volcano has erupted seven times since 1663. The last three eruptions occurred during the 20th century (1910, 1943 and 1977) and were observed by standard instruments. Although the three eruptions displayed different surface manifestations, they were, similarly, volcanisms derived from dacitic magmas. In this paper, the three eruptions are compared mainly from the viewpoint of magma movements before and during the eruptions on the basis of geophysical data, i.e. explosive, seismic and thermal activities, ground deformations, and level changes in aquifers. Post-eruption activities are also comparatively reviewed. Some phenomena related to the three eruptions are reinterpreted: for the 1910 eruption, the cryptodome model of the upheaval is rejected, and the tectonic structure of the craterlet line is proposed; for the 1943 and the 1977 eruptions, the ratios between seismic energy release and deformation are discussed; for the 1977 eruption, a tilt model of the sector deformation is proposed and relationships between anomalous changes in the aquifer level and ground upheavals are discussed. Magnitudes of the three eruptions are estimated. Tentatively, the 1943 and 1977 eruptions are roughly of the same order of magnitude and the 1910 eruption is one order of magnitude smaller.

Japans labor standard law defines weekly legal work hours, and employers must pay a 25- percent wage premium for overtime. The number of legal work hours was 48 in 1987 and gradually declined to 40 by 1997. During the corresponding period, the average weekly hours of work dropped from 45 to 41, suggesting the causal effect of legal regulation on the actual hours of work. Exploiting the different timing of the regulation change by industry and establishment size, this paper estimates the causal impact of legal work hour restriction on actual hours worked. The analysis results indicate that a one-hour reduction of legal work hours led to a reduction of 0.14 actual hours worked, but it was not accompanied by a reduction in monthly cash earnings. The recruitment of new school graduates was suppressed in response to an increase in the hourly wage rate.

Resumen En contraste con los volcanes poligeneticos, las erupciones asociadas al nacimiento de volcanes monogeneticos son mucho menos frecuentes y por tanto mas dificiles de observar y estudiar. En el mundo, solo unos pocos casos de este tipo de eventos se han registrado en tiempos historicos. Entre ellos, Jorullo (1759~1766), Paricutin (1943~1952), el maar Ukinrek (1977) y la actividad en East-Izu, Japon (1930~1989) representan algunos de los eventos que fueron reportados y estudiados de acuerdo al nivel cientifico de cada epoca. Las dos primeras erupciones formaron conos de escoria de tamano considerable y grandes flujos de lava a lo largo de varios anos de actividad, representando el nacimiento de esos volcanes. El maar se formo como consecuencia de una serie de explosiones freatomagmaticas, con escasa produccion de magmas basalticos, y East-Izu fue un evento que causo enjambres sismicos intermitentes desde 1930 y concluyo con una pequena erupcion submarina en 1989, de magnitud insuficiente para formar un cono escoriaceo. En el presente trabajo se discuten los procesos fisicos que originaron esos volcanes monogeneticos, principalmente con base a los datos sismicos disponibles y otros parametros reportados que revelan las similitudes y diferencias entre esas erupciones. Sumadas a las similitudes que caracterizan la actividad monogenetica, se distinguen diferentes tipos de volcanes. La principal caracteristica comun de todos los tipos es el origen profundo, sub-cortical, de sus fuentes magmaticas. Dependiendo de la capacidad de ascenso del magma, resultante de la sobrepresion en la fuente y en sus propiedades boyantes, la actividad eruptiva superficial puede variar desde prolongadas erupciones con alta productividad de magma formando conos cineriticos y extensos campos de lava, hasta erupciones de corta duracion y baja productividad de magmas que tienden a permanecer en la corteza sin aflorar. Casos extremos de este tipo pueden limitarse a actividad freatica derivada del calor trasferido por conduccion, o a enjambres sismicos locales. Compartiendo algunas caracteristicas con estos volcanes, pero en otra escala espacial y con una fuente magmatica somera reconocemos otro tipo de vulcanismo monogenetico, el de los conos parasitos asociados a volcanes poligeneticos que aqui se sugiere resultan del balance entre la presion magmatica y la resistencia mecanica del edificio volcanico poligenetico.Palabras clave: monogenetic volcanism, Jorullo, Paricutin, East-Izu monogenetic volcano group, parasitic cones.

LAKE KUTTYARO, in the eastern part of Hokkaido, Japan, is the western half of a circular caldera, which is one of the largest in the world, being about 20 km. in diameter. A small island at the centre of the lake and parasitic volcanoes in the other half of the caidera are supposed to have erupted after its formation.

CONTINUOUS observations of the three components of the geomagnetic field were carried out at Maddalena Island (9° 24′ E., 41° 13′ N.), the northernmost part of Sardinia, facing the Bonifacio Straits, during the period 1958–1964 by the Hydrographic Institute of the Italian Navy (see Fig. 1). The declination at Maddalena Island was about 3.5° W. in 1959. Here we report preliminary analyses of the geomagnetic variations of short periods (a few minutes–3 h) observed at this observatory; brief summaries of the diurnal variations and the K-indices have already been published1.

A crustal upheaval near Naples in March 1970 was unusual in not being accompanied by noticeable earthquakes. This could be interpreted in terms of the visco-elasticity of the Earth's crust.

The activity of Usu volcano situated at southern Hokkaido is characterized by the persistent occurrence of earthquake swarms and remarkable ground deformations including the formation of lava domes, both of which are due to the high viscosity of its magma. After the pumice eruptions of August 1977, the central part of the summit crater bounded by a U-shaped fault upheaved day after day at the maximum rate of 1 m/day. Although the rate has decreased, the total upheaval reached to about 180 m as of September 1981 resulting in formation of a new cryptodome. The doming at the summit has caused the northeastern rim to thrust towards the northeast about 180 m, and consequently caused corrugation of the ground at the northeastern foot of the volcano. The two kinds of the deformations, upheavals and thrusts, are closely related with each other. To examine the relationship between the earthquake occurrences and the deformations, a quasi-continuous observation of the distance from the northeastern rim of the summit crater to the foot of the volcano, was carried out by an optical distancemeter for 44 hours. It was found that the thrusts were episodic and accompanied by relatively large earthquakes. This supports that the earthquake swarms are caused by stick-slip motions of frictional sliding at the planes of the doming faults.