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1.
Summary. Attenuation of earthquake intensities with epicentral distance was studied by analysing the intensity data for 39 earthquakes in the United States. Attenuation of MM intensity ( I ) with distance (Δ km) follows a simple relation of the type log I = log I 0 - m Δ, where I 0 is the intensity at the epicentre and m is a constant. Slope m is found to be inversely proportional to the square of the focal depth. Intensity attenuation pattern in the United States in general can be represented by a unified relation I/I 0= exp [-(0.8999/ h 2+ 0.0014)Δ] where 16km ≤ h ≤ 60km. Intensities were calculated with the help of this equation and a good agreement with the observed intensities were found. A comparative study has also been made between the attenuation relations applicable to India and the United States.  相似文献   

2.
The spatial nature of learning is increasingly a focus of geographic inquiry. I argue that the spatiality of education, which is where formal learning occurs, has the potential to shape students’ spatial imaginaries. I analyze the role the spatiality of agronomic education plays in the historical construction of the social and physical landscape in southeastern Pará, Brazil. In opposing ways, the first Green Revolution, and agrarian social movements’ more recent agroecological Green Revolution are found to structure agronomic education and spatial imaginaries. The perspectives of agricultural extension agents trained in traditional agronomic programs are compared with teachers from an agroecological school located in an Amazonian agrarian reform settlement of Brazil's Landless Workers’ Movement. I collected these data over 17 months of ethnographic fieldwork. To analyze these data, I employ a political ecology of education perspective, which highlights how education and political economy interact to mediate relations with, access to, and contestations over natural resources. The geography of education and the education of geography exist in a complicated feedback cycle: Education is not neutral but ideologically charged and affects conceptions of productive landscapes, providing students intellectual and economic power to put their visions of landscape into effect.  相似文献   

3.
In this paper I reflect on some key methodological tensions that emerged during my PhD research. The research critically analyses the political struggles of outworking1 women from Chinese, Vietnamese and Cambodian backgrounds in Sydney, Australia, for minimum wages and a monitoring of ethical networks in the clothing industry from 1997 to 2002. Rather than present 'key findings' in this paper I instead reveal how I began to think more critically and in less absolute ways about reading the multiple voices of outworkers, NGO workers and my own voice as researcher, activist and English teacher. I drew insights from Bakhtin's dialogism for thinking about research as shaped by sets of conversations. In this paper I reflect on several 'in-the-field' interactions: organising interviews, interviewing outworkers through an interpreter, storytelling in a rights-based English class setting, and how I and other participants represented outworking women in different forums. Dialogism required I take seriously the concept that knowledges are socially constructed in very particular contexts and this led to a rejection of my earlier notion of a singular authentic voice for outworking women or for me as researcher.  相似文献   

4.
Mitt bidrag til Norges karthistorie III, offentiliggjort I 1943 I dette tidsskrifts bind IX, s. 79—103, som en minnetale til 250-åsdagen for Melchior Ramus' død 25/2 1693, ble åpnet med et sitat av en uttalelse om ham av hans samtidige navnebror. Den lærde prost I Meldalen, Melchior Augustinussøn, at han «Var hel unique1 og en kostelig lærd Mand I alle Faculteter». Or i en annen forbindelse uttalte ha nom Melchior Ramus: «Han var en mann av mer sjelden lærdom og begavelse, idet han ikke befattet sig med det sedvanlige, men det ualminnelige og særegne. Han var en god astronom, enda bedre geometriker og best som telog».  相似文献   

5.
In this article we show that the Voronoi-based nine-intersection (V9I) model proposed by Chen et al. (2001, A Voronoi-based 9-intersection model for spatial relations. International Journal of Geographical Information Science, 15 (3), 201–220) is more expressive than what has been believed before. Given any two spatial entities A and B, the V9I relation between A and B is represented as a 3 × 3 Boolean matrix. For each pair of types of spatial entities that is, points, lines, and regions, we first show that most Boolean matrices do not represent a V9I relation by using topological constraints and the definition of Voronoi regions. Then, we provide illustrations for all the remaining matrices. This guarantees that our method is sound and complete. In particular, we show that there are 18 V9I relations between two areas with connected interior, while there are only nine four-intersection relations. Our investigations also show that, unlike many other spatial relation models, V9I relations are context or shape sensitive. That is, the existence of other entities or the shape of the entities may affect the validity of certain relations.  相似文献   

6.
Summary. The Cordova gabbro of southern Ontario intrudes 1300 Myr old volcanic rocks of the Hastings Lowlands in the Grenville Structural Province. Three distinct vector magnetizations (A, B and C) have been isolated, using a combination of stable endpoints, subtracted vectors from orthogonal vector plots and converging remagnetization circles. The A magnetization, with mean direction D = 294° I =– 55.5° ( k = 42, α95= 5.5°, N = 18 sites), is a high coercivity, high blocking temperature remanence recorded by 49 samples. The B magnetization was isolated in 33 samples and has a mean direction D = 305.5° I =– 1.5° ( k = 24, α95, N = 11 sites). B has lower coercivities and blocking temperatures than A where the two are superimposed. The A and B palaeopoles, 151°E, 10.5°S ( dp = 6°, dm = 8°) and 165.5°E, 24°N ( dp = 5°, dm = 9.5°), fall on the Grenville Track around 900 and 820 Ma respectively. The A and B magnetizations thus date from uplift and cooling following the Grenvillian orogeny. The third magnetization, the C component, has been isolated in 23 samples. Its mean direction is D = 180° I = 27.5° ( k = 18, α95= 10.5°, N = 12 sites). The C is a low coercivity, low blocking temperature overprint of A and B. Its palaeopole, 102°E, 31°N ( dp = 6.5°, dm = 12°), is unlike post-1300 Precambrian poles for cratonic North America but matches Silurian and late Ordovician poles. 40Ar/39Ar plateau ages of 446 and 447 Ma determined by Lopez-Martinez and York for plagioclases from one of the Cordova samples confirm this age assignment. The C magnetization therefore records a previously unrecognized mild thermal or hydrothermal event that occurred in Palaeozoic time, long after the Grenvillian orogeny.  相似文献   

7.
I de siste 20 år har Opmålingen arbeidet med å skaffe en grunnleggende 1. ordens hovedtriangulering, som kan tilfredsstille de krav som stilles til den fra den topografiske kartlegning, hydrograferingens, den økonomiske kartoptagnings og videnskapens side. Arbeidet har foregått under stadig utvikling av metoder og instrumenter. Dette hovedtriangelnett overspenner nu en større del av Sør-Norge og en vesentlig del av Troms fylke. I forbindelse med trianguleringen utføres basismålinger og astronomiske arbeider.  相似文献   

8.
Summary. This note presents an exact analytical formula for determining the magnitude of coseismic surface volume change (δ V ) of earthquake faults in a half-space. For a Poisson solid, the formula is remarkably simple; δ V = M zz |8μ, where M zz is one of the moment tensor elements of the source. Maximum δ V values derive from dip slip on faults plunging 45°. For these events, surface volume changes of 0.0001 and 4.3 km3 can be expected for magnitude 5 and 8 earthquakes respectively. All of the coseismic surface volume change is recovered in the interseismic period through relaxation of the Earth and rebound of the surface. A useful rule of thumb for estimating the magnitude of vertical rebound in 45° dip slip events is δ h p=Δ s /24, where Δ s is the coseismic slip on the fault.  相似文献   

9.
Summary. Fifty-six orientated samples were collected from 13 sites on five dolerite dykes (between lat.14°23°N, long.77°43'E and lat.14°08'N, long. 77°49'E), which adjoin the south-western margin of the Cuddapah basin in Anantapur district, Andhra Pradesh. After af demagnetization, two dykes (five sites) striking ENE possess similar magnetic directions, (1) D = 57°, 1=-69° (K = 52, α95= 7°) and (2) D = 71°, I = -72° ( K = 260, α95= 5°). Again dykes (3) (three sites), and (4) (two sites) have similar strike (NE) and magnetic directions, D = 64°. I=-7 α( K = 142, α95 = 8°) and D = 53°, I =-8° (K = 142, α95= 6°) and dyke (5) (two sites) striking NW shows D = 320°, I = -34° ( K = 68, α95= 13°). Remanent directions estimated from total field magnetic anomaly data agree well with these results. Synthesis of these data with 10 other published palaeomagnetic studies of Precambrian dolerite dykes on the Indian peninsula, suggest that these three systems of dykes adjoining the Cuddapah basin had been emplaced prior to the basin formation perhaps representing the initial thermal event responsible for the basin development and also that there have been at least three separate periods of dyke emplacement on this shield. The radiometric data, however, are very sparse and these periods cannot be dated with confidence.  相似文献   

10.
The spatial and temporal variations of stable oxygen isotope in precipitation on different time scales are analyzed according to the data from the IAEA/WMO stations with long survey series in the Northern Hemisphere. Temperature effect is mainly distributed in mid-high latitudes on seasonal scale except for Bamako and Addisababa stations. The δ18O/temperature slope displays the positive correlation against altitude for most of the statistical stations. Amount effect appears primarily in the region south of 30°N and coastal areas. The δ18O/precipitation slope is indirectly proportional to precipitation amount. For some of the sampling stations at mid-high latitudes where their seasonal distribution of precipitation is contrary to that of temperature, coupled with temperature effect, the amount effect appears synchronistically. Either the temperature effect or the amount effect on seasonal scale, there are positive correlations to a certain extent between the annual weighted mean δ18O and the annual mean temperature for almost all the stations. The correlation between composite δ18O and temperature on spatial scale is much more marked, compared with that of individual station. There is a good agreement between 10-year moving average temperature curves I and II, with the values of the former all markedly smaller than corresponding ones of the latter, calculated by the monthly mean series group I and the annual mean series group II, respectively. However, two calculated dδ18O/dT curves display the distinct difference: the variation amplitude of slope series II is larger than that of slope series I. Both curves had similar ascending trend from the 1960s to the 1970s, and then, their variations display the anti-phase. Moreover, the analyses show that there is negative correlation between slope series FI and temperature series II. However, the status is different for slope series I and temperature series I. Both series have contrary trend from the 1960s to the 1970s, whereas the same trend since the 1980s.  相似文献   

11.
I Europa er der for den fremtidige geografiske forskning neppe egentlige opdagelser å gjøre. Men detaljundersøkelsen har arbeide nok. Dette nye norske geografiske tidsskrift tor ha en særlig opgave i å bokføre nyt utforskningsarbeide av geografisk art i vårt eget land.  相似文献   

12.
I årene 1930 og 1931 har der været folketellinger i de fleste land. Uaktet tidspunktet har været noget forskjellig, gir tellingene allikevel nogenlunde kommensurable resultater, da de fleste har funnet sted i slutten av 1930 eller i begynnelsen av 1931. Tellingene gir oss den omtrentlige status av jordens befolkning ved årsskiftet 1930—31. I det følgende skal jeg søke å holde tidsskriftets lesere a jour med de viktigste resultater. Hvor intet annet er sagt, er tallene tatt fra de offisielle publikasjoner, utgitt av de forskjellige lands statistiske byråer. Bare få land har ennu rukket å få utgitt oversikter over resultatene, men efter hvert som de kommer, vil de bli referert. Tallene i det efterfølgende er ganske lett avrundet.  相似文献   

13.
I Denne Foreløpige rapport fra undersøkelsesområdet (fig. 1) er det gjort forsøk på å se isavsmeltingsforløpet på den sentrale og den distrale side av hovedvasskillet under ett. Med sentral side meines området mellom hovedvasskillet og iskulminasjonen (fig. 2). I avsmeltingsbildet er hoved-vasskillet en markert skillelinje, og det er likevel studier langs denne skillelinjen som lettest synes å kunne binde de to ulike sidene sammen.  相似文献   

14.
Efter et fravær av bortimot fire år vendte konsul Lars Christensens undersøkelsesskib »Norvegia« via Cape Town tilbake til Sandefjord den 15. mai 1931.

Siden skibet forlot Norge 26. september 1927 har det foretatt fire tokt i Sydhavet.

På det forste tokt 1927—1928 blev der arbeidet på Bouvet-oia, i havet omkring den og sondenfor.

I sesongen 1928å1929 strakte arbeidsfeltet sig fra Bouvet-oia til havet vest for Syd-Shetland, i syd til 71° 11' S og i vest til 140° 49' W.

I den folgende sesong 1929—1930 kartlagdes ved flyvning vestre del av Enderby Land, Dronning Maud Land og vestre del av Kronprinsesse Martha Land, ost for Coats Land.

Planen for »Norvegia«s fjerde tokt, 1930—1931, var under omseiling av Sydpollandet a foreta undersokelser av hvalforekomster og åte, merking av hval samt oseanografiske og meteorologiske undersokelser. Videre skulde man undersoke om de tvilsomme øier, Trulsoia, Nimrod-oiene og Dougherty-oia eksisterte.

Fartøiets besetning og utstyr var alt pa vei til Cape Town  相似文献   

15.
New palaeomagnetic data from the Lower and Middle Cambrian sedimentary rocks of northern Siberia are presented. During stepwise thermal demagnetization the stable characteristic remanence (ChRM) directions have been isolated for three Cambrian formations. Both polarities have been observed, and mean ChRM directions (for normal polarity) are: Kessyusa Formation (Lower Cambrian) D = 145°, I = -40°, N = 12, α95= 12.8°; pole position: φ= 38°S, A = 165°E; Erkeket Formation (Lower Cambrian, stratigraphically highly) D = 152°, I = - 47°, N = 23, α95= 6.8°; pole position: φ= 45°S, A = 159°E; Yunkyulyabit-Yuryakh Formation (Middle Cambrian) D = 166°, I = - 33°, N = 38, α95= 4.6°; pole position: φ= 36°S, L = 140°E. These poles are in good agreement with the apparent polar wander path based on the bulk of existing Cambrian palaeomagnetic data from the Siberian platform. In Cambrian times, the Siberian platform probably occupied southerly latitudes stretching from about 35° to 0°, and was oriented 'reversely' with respect to its present position. Siberia moved northwards during the Cambrian by about 10° of latitude. This movement was accompanied by anticlockwise rotation of about 30°. The magnetostratigraphic results show the predominance of reversed polarity in the Early Cambrian and an approximately equal occurrence of both polarities in the part of the Middle Cambrian studied. These results are in good agreement with the palaeomagnetic polarity timescale for the Cambrian of the Siberian platform constructed previously by Khramov et al. (1987).  相似文献   

16.
《Polar Science》2014,8(1):10-23
This study compares the common harmonic constants of the O1, K1, P1, Q1, M2, S2, N2, and K2 tidal constituents from eight global and four regional tide models with harmonic constants from satellite altimeter and tide gauge data for the northern region of the Antarctic Peninsula (58°S–66°S, 53°W–66°W). To obtain a more representative comparison, the study area was divided into three zones with different physical characteristics but similar maximum tidal amplitude variations: Zone I (north of 62°S), Zone II (south of 62°S and west of the Antarctic Peninsula), and Zone III (between 62°S and 64.3°S, and east of 58.5°W). Root sum square (RSS) values are less than or equal to 3.0, 4.2, and 8.4 cm for zones I, II, and III, respectively. No single model shows superior performance in all zones. Because there are insufficient satellite altimetry observations in the vicinity of Matienzo Base (64.9761°S, 60.0683°W), this station was analyzed separately and presents the greatest values of both root mean square misfit and RSS. The maximum, minimum, and average amplitude values of the constituents that follow in importance after the eight common tidal constituents, and which have amplitudes greater than 1 cm, are also analyzed.  相似文献   

17.
I invert a large set of teleseismic phase-anomaly observations, to derive tomographic maps of fundamental-mode surface wave phase velocity, first via ray theory, then accounting for finite-frequency effects through scattering theory, in the far-field approximation and neglecting mode coupling. I make use of a multiple-resolution pixel parametrization which, in the assumption of sufficient data coverage, should be adequate to represent strongly oscillatory Fréchet kernels. The parametrization is finer over North America, a region particularly well covered by the data. For each surface-wave mode where phase-anomaly observations are available, I derive a wide spectrum of plausible, differently damped solutions; I then conduct a trade-off analysis, and select as optimal solution model the one associated with the point of maximum curvature on the trade-off curve. I repeat this exercise in both theoretical frameworks, to find that selected scattering and ray theoretical phase-velocity maps are coincident in pattern, and differ only slightly in amplitude.  相似文献   

18.
I begynnelsen av mars 1927 fikk nærværende forfatter fra konsul Lars Christensen, Sandefjord, meddelelse om at det var lykkedes den av ham i stillhet utsendte hvalbåt »Odd I« å nå frem til Peter den førstes ø i Vest-Antarktis og at der på ferden rimeligvis var blitt innsamlet materiale av videnskapelig interesse.  相似文献   

19.
Summary. Study of the palaeomagnetism of two complexes from the Newer Granite Suite in Scotland, at Ratagan (NW Highlands) and Comrie (central Highlands), reveals the variable nature of the natural remanence encountered in granodioritic intrusions and the surrounding metamorphic country rock. Forty-eight specimens from Ratagan, dated at 415 ± 5 Ma, gave a mean direction: D = 8°, I =−32°, and a palaeomagnetic south pole: 15°S, 346°E (δ p = 5°, δ m = 9°). Twenty-eight specimens from Comrie, dated at 408±5 Ma, gave a mean direction: D = 75°, I =−30°, and a palaeomagnetic south pole: 6°S, 287°E (δ p = 4°, δ m = 7°). These results have been compared with the established apparent polar wander path (APWP) for Britain. The Ratagan pole improves the reliability of the APWP but doubt remains as to whether the primary magnetization from Comrie represents a true late Silurian direction or whether it has been affected by post-cooling rotation, possibly associated with the nearby Highland Boundary Fault.  相似文献   

20.
Summary. ARM and I sr stability with respect to alternating field and low-temperature treatment were measured for a set of artificial rock specimens. Each of the specimens contained a known amount of a natural magnetic mineral of a known grain size. The following minerals were used: a homogeneous natural magnetite, a natural titanomagnetite with submicroscopic Fe-rich inclusions, and a natural titanomagnetite and a natural titano-maghemite that both show exsolution phenomena. The grain size of the fractions varied from < 5 to 250 μm. It is found that the stability of ARM and I rs of multi-domain grains with respect to alternating fields and low-temperature treatment is similar, whereas for the smallest grains studied (< 5 μm) ARM is more stable than I sr. Multi-domain ARM data from this study are in agreement with current multi-domain ARM theory. Low-temperature behaviour of ARM and I sr can be explained either in terms of a model in which stable moments in the bulk of the grains are screened by the surrounding matrix or in terms of a model in which regeneration of the bulk remanence plays a role and in which stable moments are situated on the surfaces of the grains.  相似文献   

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