Earthquake source and propagation parameters in New Zealand     

R.D. Adams 《Tectonophysics》1978,49(3-4)

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Estimating palaeowind strength from beach deposits – Reply     

Kenneth D. Adams 《Sedimentology》2004,51(3):671-673

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Human Strategies for Coping with El Niño Related Drought in Amazônia     

Emilio F. Moran  Ryan Adams  Bryn Bakoyéma  Stefano Fiorini T.  Bruce Boucek 《Climatic change》2006,77(3-4):343-361

This article reports on findings of a research project examining farmers' coping strategies in the Brazilian Amazon in response to El Niño related weather events. We examine the extent of vulnerability of small and large farmers to these events in a tropical rainforest environment. Little attention has been given to the impact of ENSO events in Amazônia, despite evidence for devastating fires during ENSOs. Although we found a range of locally developed forecasting techniques and coping mechanisms, farmers have sustained significant losses, and we suggest that increased access to scientific forecasts would greatly enhance the ability of the farmers in our study area to cope with El Niño related weather events. In Amazônia the El Niño phase of the El Niño-Southern Oscillation (ENSO) climate pattern leads to an extended period of reduced rainfall (Hobbs et al., 1998). This period of reduced rainfall can result in significant agricultural losses for farmers and ranchers in the area and in increased forest flammability. We have found that the majority of our study population uses several methods of forecasting, coping with, and adapting to drought events – and they recognize the economic losses they can experience and the loss of forests through the accidental spread of fire. The poorest farmers in our study area experience El Niño related drought events as a serious threat to their livelihoods. Their vulnerability is heightened during extreme climate events and our observations revealed that all of the farmers in our study would benefit from increased availability of improved forecast information relevant to their locality and their current farming strategies. This paper examines the availability and use of forecasts, the occurrence of accidental fires and techniques to prevent fire related losses, and the coping mechanisms for dealing with El Niño related drought in the agricultural regions surrounding the cities of Altamira and Santarém, in Pará State, Brazil. Distribution of an El Niño Prediction Kit at the end of the study and a series of workshops may lead to better local information on rainfall variability and create a farmer-maintained grid of collecting stations to sensitize farmers to the variability of precipitation in the region, and on their property.  相似文献   

The olivine — clinopyroxene geobarometer: experimental results in the CaO-FeO-MgO-SiO2 system     

Gerald E. Adams  Finley C. Bishop 《Contributions to Mineralogy and Petrology》1986,94(2):230-237

The exchange of Ca and Mg between olivine and clinopyroxene has been studied in the CFMS system. Experiments were conducted in a piston-cylinder apparatus in the temperature range of 1,100–1,300° C and the pressure range 10–30 kbar. Results confirm the previous suggestion (Adams and Bishop 1982) that this reaction has a sufficiently large V° to be used as a geobarometer in several basic and ultrabasic systems. Experimental results were corrected for compositional effects using recent activity-composition models for quadrilateral pyroxenes and olivines. The corrected results indicate that the exchange reaction has aH _{1 bar} of 34,900 J, a S° of -7.25J/deg, and a V° of -0.489 J/bar. Corrected results agree well with calculations based on the thermodynamic properties of the endmembers.Application of the olivine-clinopyroxene geobarometer to many systems will require additional calibration of non CFMS components. Preliminary pressure estimates based on simple assumptions about the activity relations of these components have been made for spinel lherzolites from southwestern United States and coarse and porphyroclastic garnet lherzolites from southern Africa. A geotherm calculated from spinel lherzolites near the Rio Grande rift is consistent with a geophysical geotherm based on near-surface heat-flow measurements of 100 mW/m² or greater. Results on garnet lherzolites yield a southern African geotherm with no inflection which falls at somewhat higher temperatures than pyroxene geotherms calculated for the same area.  相似文献   

The environmental effects of dam construction in tropical Africa: Impacts and planning procedures     

W.M. Adams  F.M.R. Hughes   《Geoforum》1986,17(3-4)

Dam construction can have significant effects on downstream floodplain environments in tropical Africa. The impacts of river control on floodplain forests in the Tana River Valley in Kenya, and on floodplain agriculture in the Sokoto River Valley in Nigeria are described. The extent to which downstream impacts were understood or predicted in these case studies are described, and the implications of this for environmental appraisal in project planning are assessed.  相似文献   

Definition and detailed characterization of Lunar surface units using remote observations     

James W. Head  Carle Pieters  Thomas McCord  John Adams  Stanley Zisk 《Icarus》1978,33(1):145-172

Remote sensing techniques and data may be subdivided into three principal types according to how they are used: (1) defining techniques help to define unit boundaries and extent; (2) characterizing techniques allow classification and characterization of physical features, lithology, or chemical composition; (3) supporting techniques provide additional useful information but are not fundamental to the definition or characterization of units. Defined units represent a fundamental subdivision of the rocks in a planetary crust and thus represent processes and sequences of events. The definition and characterization of units provides a framework for the interpretation of planetary processes and history. Detailed consideration of unit definition and characterization is presented using the mare deposits of the Imbrium basin as an example. This example provides guidelines for the utilization of remote sensing techniques in geologic mapping of the Moon and other planets.  相似文献   

A new technique for the determination of coronal magnetic fields: A fixed mesh solution to Laplace's equation using line-of-sight boundary conditions     

John Adams  G. W. Pneuman 《Solar physics》1976,46(1):185-203

A new method for computing potential magnetic field configurations in the solar atmosphere is described. A discrete approximation to Laplace's equation is solved in the domain R r R ₁, 0 , 0 2 (R ₁being an arbitrary radial distance from the solar center). The method utilizes the measured line-of-sight magnetic fields directly as the boundary condition at the solar surface and constrains the field to become radial at the outer boundary, R ₁. First the differential equation and boundary conditions are reduced to a set of two-dimensional equations in r, by Fourier transforming out the periodic dependence. Next each transformed boundary condition is converted to a Dirichlet surface condition. Then each two-dimensional equation with standard Dirichlet-Dirichlet boundary conditions is solved for the Fourier coefficient it determines. Finally, the solution of the original three dimensional equation is obtained through inverse Fourier transformation. The primary numerical tools in this technique are the use of a finite fast Fourier transform technique and also a generalized cyclic reduction algorithm developed at NCAR. Any extraneous monopole component present in the data can be removed if so desired.The code was developed for the HAO solar-interplanetary modeling effort in response to the following specific requirements:

(1)	High resolution.
(2)	Speed in computation.
(3)	Sufficiently accurate solutions of Laplace's equation at all heights.

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Slow earthquakes and great earthquakes along the Nankai trough   总被引：2，自引：0，他引：2  

Alan T Linde  I.Selwyn Sacks 《Earth and Planetary Science Letters》2002,203(1):265-275

We have reexamined reports indicating that slow deformation occurred before the great Japan earthquakes of 1944 (Tonankai) and 1946 (Nankaido) and find that the observations are well founded. Although no quantitative models have previously been proposed to explain all of the relevant data we show that they are satisfied by a simple model for both earthquakes. The model, based on known properties of subduction zones, has slow slip on the subduction interface in an area deeper than the seismic rupture. If this model is correct and a similar physical situation holds for an anticipated Tokai earthquake, existing instruments will be able to reveal the pre-slip in real time. While differences among the deformation time series at different sites will provide strong constraints on the slow rupture propagation, these differences could result in delaying the recognition of a coherent event.  相似文献   

Constraints on Infrasound Scaling and Attenuation Relations from Soviet Explosion Data     

J. L. Stevens  I. I. Divnov  D. A. Adams  J. R. Murphy  V. N. Bourchik 《Pure and Applied Geophysics》2002,159(5):1045-1062

—?The Institute for the Dynamics of the Geospheres (IDG) in Moscow, Russia, contains an archive of infrasound recordings from Soviet atmospheric nuclear tests that were conducted in 1957 and 1961, and has digitized the highest quality records from this data set. We have measured the infrasound signals from these records and compared them with previously developed scaling and attenuation relations. We find that the data are in best agreement with a scaling and attenuation relation developed by the Los Alamos National Laboratory (LANL) which can be written as logP = 3.37 + 0.68 logW? 1.36logR where P is zero to peak pressure amplitude in Pascals, W is the yield in kilotons, and R is the source to receiver distance in kilometers. We use the scaling relations to define an infrasound magnitude, and to estimate the detection capability of the International Monitoring System (IMS) being developed as part of the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The detection threshold for the proposed 60-station IMS network is estimated to be slightly higher than the CTBT design goal of 1 kiloton in some locations.  相似文献   

Estimating the carbon transfer between the ocean, atmosphere and the terrestrial biosphere since the last glacial maximum     

M.A. Maslin  J. Adams  E. Thomas  H. Faure  R. Haines-Young 《地学学报》1995,7(3):358-366

Carbon dioxide records from polar ice cores and marine ocean sediments indicate that the last glacial maximum (LGM) atmosphere CO₂ content was 80–90 ppm lower than the mid-Holocene. This represents a transfer of over 160 GtC into the atmosphere since the LGM. Palaeovegetation studies suggest that up to 1350 GtC was transferred from the oceans to the terrestrial biosphere at the end of the last glacial. Evidence from carbon isotopes in deep sea sediments, however, indicates a smaller shift of between 400 and 700 GtC. To understand the functioning of the carbon cycle this apparent discrepancy needs to be resolved. Thus, older data have been reassessed, new data provided and the potential errors of both methods estimated. New estimates of the expansion of terrestrial biomass between the LGM and mid-Holocene are 700 GtC ± > 300 GtC, using the ocean carbon isotope-based method, compared with of 1100 GtC ± > 500 GtC using the palaeovegetation estimate. If these estimates of the carbon shift to the terrestrial biosphere are equilibrated with the dissolved carbon in the oceans, and the CaCO₃ compensation of the ocean is taken into account, then the glacial atmospheric CO₂ would have been between 50 (± 30) ppm and 95 (± 50) ppm higher. The glacial atmosphere therefore should have had a CO₂ partial pressure of between 330 and 375 μatm. Hence, a rise of between 130 and 175 μatm in atmospheric CO₂, rather than 80 μatm, at the end of the last glacial must be accounted for.  相似文献