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1.
There were 407 deaths from wind-related tree failures in the United States, 1995–2007. The most common cause of the deadly fallen tree was a thunderstorm (41%), followed by nonconvective high winds (35%), tropical cyclones (14%), tornadoes (7%), and snow and ice (3%). Most (62%) of the deaths were males while the median age was 44 years. The most common location of the fatality was in a vehicle struck by the tree or a vehicle that crashed into a downed tree on the road (44%), followed by persons outdoors (38%), in mobile homes (9%), and in frame houses (9%). Persons killed by wind-related tree failures during tropical cyclones and tornadoes were more commonly at home (40%) when struck than those killed at home by thunderstorm and nonconvective high winds (13%). Seasonality of the deaths varied by weather type with deaths in thunderstorms clustered during May–August, nonconvective high winds October–April, tropical cyclones August–October, tornadoes in April and November, and snow and ice December–April. Regional patterns result from frequency of the wind events, population density, and tree cover. Suggestions are made for hazard reductions.  相似文献   

2.
Property insurance data available for 1949–2006 were assessed to get definitive measures of hurricane losses in the U.S. Catastrophes, events causing >$1 million in losses, were most frequent in the Southeast and South climate regions. Losses in these two regions totaled $127 billion, 85% of the nation’s total losses. During the period 1949–2006 there were 79 hurricane catastrophes, causing $150.6 billion in losses and averaging $2.6 billion per year. All aspects of these hurricanes showed increases in post-1990 years. Sizes of loss areas averaged one state in 1949–1967, but grew to 3 states during 1990–2006. Seven of the ten most damaging hurricanes came in 2004 (4) and 2005 (3). The number of hurricanes also peaked during 1984–2006, increasing from an annual average of 1.2 during 1949–1983 to 2.1 per year. Losses were $49.3 billion in 1991–2006, 32% of the 58-year total. Various reasons have been offered for such recent increases in hurricane losses including more hurricanes, more intense tropical storms, increased societal vulnerability in storm-prone areas, and a change in climate due to global warming, although this is debatable.  相似文献   

3.
With increasing high-quality geological and geophysical data it becomes clear that seismicity of the continents is characterized by linear patterns which are closely associated with tectonic features. The aim of this paper is to give reasonable interpretation for the earthquake distribution in the contiguous continent of the United States. Seismic lines and earthquake concentrated zones are defined, which reflect the characteristics of the continental seismotectonics. Similarities and differences in seismotectonics between the continental part of China and the contiguous continent of US are analysed. It is demonstrated that the spatial distribution of earthquakes can provide the information of the active structures in the earth's crust. The authors consider that the patterns of continental seismotectonics are not only controlled by the pre—existing tectonic frameworks and the current boundary dynamic conditions, but also possibly affected by dynamic factors of global tectonics at a higher level.  相似文献   

4.
Beta convergence theorizes that regions with low levels of income will grow faster than regions with higher incomes as investment is moved to regions where returns can be maximized. The formal test for beta convergence is an OLS regression with income change as the dependent variable and initial income as the predictor. Beta convergence is present when the coefficient on initial income is negative. Empirical evidence of convergence is mixed, however. We contend that omission of spatial effects, and the confounding problem of geographic scale, help explain inconsistent empirical findings. We, therefore, examine the role of spatial effects on the standard convergence model at three spatial scales—states, Economic Areas, and counties—in the United States from 1970 to 2004. Our results indicate failure to account for spatial and scalar effects can lead to conflicting results. Convergence evidence is strongest at smaller levels of spatial aggregation, yet model fit is better at larger levels. In addition, accounting for spatial effects improves model diagnostic performance but weakens convergence evidence.  相似文献   

5.
Analytical results for Pb-concentrations and isotopic ratios from ca. 150 samples of soil A horizon and ca. 145 samples of soil C horizon collected along a 4000-km east–west transect across the USA are presented. Lead concentrations along the transect show: (1) generally higher values in the soil A-horizon than the C-horizon (median 21 vs. 16.5 mg/kg), (2) an increase in the median value of the soil A-horizon for central to eastern USA (Missouri to Maryland) when compared to the western USA (California to Kansas) (median 26 vs. 20 mg/kg) and (3) a higher A/C ratio for the central to eastern USA (1.35 vs. 1.14). Lead isotopes show a distinct trend across the USA, with the highest 206Pb/207Pb ratios occurring in the centre (Missouri, median A-horizon: 1.245; C-horizon: 1.251) and the lowest at both coasts (e.g., California, median A-horizon: 1.195; C-horizon: 1.216). The soil C-horizon samples show generally higher 206Pb/207Pb ratios than the A-horizon (median C-horizon: 1.224; A-horizon: 1.219). The 206Pb/207Pb-isotope ratios in the soil A horizon show a correlation with the total feldspar content for the same 2500-km portion of the transect from east-central Colorado to the Atlantic coast that shows steadily increasing precipitation. No such correlation exists in the soil C horizon. The data demonstrate the importance of climate and weathering on both Pb-concentration and 206Pb/207Pb-isotope ratios in soil samples and natural shifts thereof in the soil profile during soil-forming processes.  相似文献   

6.
Tsunami-like intense sea-level oscillations, associated with atmospheric activity (meteorological tsunamis), are common in the Great Lakes and on the East Coast of the United States. They are generated by various types of atmospheric disturbances including hurricanes, frontal passages, tornados, trains of atmospheric gravity waves, and derechos. “Derecho” is a rapidly moving line of convectively induced intense thunder storm fronts producing widespread damaging winds and squalls. The derecho of June 29–30, 2012 devastatingly propagated from western Iowa to the Atlantic coast, passing more than 1,000 km and producing wind gusts up to 35 m/s. This derecho induced pronounced seiche oscillations in Lake Michigan, Chesapeake Bay, and along the US Atlantic coast. Sea-level records from the updated National Oceanic and Atmospheric Administration (NOAA) tide gauge network, together with the NOAA and automated surface-observing system air pressure and wind records, enabled us to examine physical properties and temporal/spatial variations of the generated waves. Our findings indicate that the generation mechanisms of extreme seiches in the basins under study are significantly different: energetic winds play the main role in seiche formation in Chesapeake Bay; atmospheric pressure disturbances are most important for the Atlantic coast; and the combined effect of pressure oscillations and wind is responsible for pronounced events in the Great Lakes. The “generation coefficient,” which is the ratio of the maximum observed sea-level height and the height of air pressure disturbance, was used to map the sea-level response and to identify “hot spots” for this particular event, i.e., harbors and bays with amplified seiche oscillations. The Froude number, Fr = U/c, where U is the speed of the atmospheric disturbance and c is the long-wave speed, is the key parameter influencing the water response to specific atmospheric disturbances; the maximum response was found for those regions and disturbance parameters for which Fr ~1.0.  相似文献   

7.
In the United States, there is a growing awareness of the implications of our globalized food system, a system that incorporates all manner of agriculture, food distribution, food processing and transformation, and consumption. The ever increasing distance between where our food is produced and where it is consumed has helped spur a movement to develop a system of place based foods. Right now multiple models are in play, including farmers markets, community supported agriculture, and the localvore movement. This article will do a close examination of another model from France, the French system of appellation d’origine contrôlée (AOC); nationally regulated by the French Ministry of Agriculture it supports and protects foods and drinks with unique links to particular territories. The AOC system is based on geographically distinct and historically specific food and drink found throughout France. By closely examining one AOC product—Comté cheese produced in the rural agricultural region in Jura—the authors consider the possibilities for an AOC-style system in the United States.  相似文献   

8.
Analyses of regional carbon sources and sinks are essential technologies in mitigating the accumulation of CO2 in the for assessing the economical feasibility of various carbon sequestration atmosphere and in preventing global warming. Such an inventory is a prerequisite for the regional trading of CO2 emission. As a U.S. Department of Energy Southeast Regional Carbon Sequestration Partner, we have estimated the state-level terrestrial carbon pools in the southeast and south-central US, and have projected the potential for terrestrial carbon sequestration in the region. This region includes: Alabama, Arkansas, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Texas, and Virginia. The total terrestrial carbon storage in southeast and south-central US (11 states) was estimated to be 21.1 Pg C. Total annual terrestrial carbon sink in the region was calculated to be 189.1 Tg C/a. Of the various carbon sinks, the annual forest carbon sink (estimated as 76 Tg C g/a) could compensate for 13% of the total annual greenhouse gas emission in the region in the early 1990s. Through proper policies and the use of best management practices, a further 9.3% of the total greenhouse gas emission could be offset by terrestrial sequestration (53.9 Tg C/a).  相似文献   

9.
Recent years have witnessed debates in the American South between traditional white Southerners and African American Southerners over whether and how symbols from the region's two defining historical events – the Civil War and the Civil Rights movement – are displayed on the region's landscape. This paper examines the most contentious of these debates, the conflict over government sanction for flying the various flags of the Confederate States of America. This article first discusses the concepts of iconography and public memory, and then the role of Confederate flags in traditional white Southern iconography. We then examine four recent attempts in the states of Georgia, Alabama and South Carolina, and within the chambers of the U.S. Senate to remove government sanction for flying Confederate flags. We conclude from these debates that while icons can act as centripetal forces binding a people together, they can also emerge as centrifugal forces, further splitting apart a region's population along major cultural and racial divisions.  相似文献   

10.
Geochemical studies of the Middle—Late Cenozoic succession of volcanic rocks from the northern part of the Rio Grande Rift were conducted. The initial activation of the rift structure was coeval with voluminous eruptions of lava and pyroclastic material of mainly intermediate and acid compositions in the San Juan volcanic field 35–27 Ma. The composition of the volcanic products after the rifting was dominated by basic and intermediate lavas. It is shown that the basanites and alkali basalts of the territory had geochemical characteristics of sublithospheric slab and above–sl ab sources. The processes of the riftogenic thinning of lithosphere are expressed by geochemical parameters that reflect the interaction between the liquids from the sublithospheric mantle and the rocks from different levels of both the lithospheric mantle and lower crust. In the 35–18 Ma interval, melts of different–depth sublithospheric and lithospheric sources erupted simultaneously in the northern part of the rift. However, the products of interaction between the sublithospheric and lithospheric materials dominated later in the past 15 Ma, although the sublithospheric magmatic liquids erupted at the northern structural termination of the rift within the Yampa volcanic field at about 10 Ma.  相似文献   

11.
Doklady Earth Sciences - The content of polycyclic aromatic hydrocarbons (PAHs) in soil and snow cover near the carbon black plants in Moscow, Omsk, and Samara regions was studied. The differences...  相似文献   

12.
During 1990–1996 the United States experienced record-setting insured property losses due to numerous weather catastrophes, each event causing $100 million or more in losses (1991 dollars). The total loss in this 7-year period, after adjustment to inflation and other factors, was $39.65 billion with $15 billion coming from one event, Hurricane Andrew. In the 1990s, 72 catastrophes occurred, half of the total number in the 40 preceding years, 1950–1989. Although the total loss and the number of catastrophes were exceptionally high in the 1990s, the average loss per event was $551 million, only slightly more than the $467 million average for catastrophes during 1950–1989. Furthermore, storm intensities in the 1990s were slightly less than those during the preceding 40 years, revealing the excess losses of the 1990s to be a result of an extremely large number of damaging storms causing losses exceeding $100 million. Examination of historical values of most weather extremes including hurricanes, floods, and tornadoes, did not show an increase during the 1990s, revealing that weather changes were not the principal cause of more catastrophes. Examination of recent demographic shifts in the U.S. reveals two changes, each based on major re-locations to higher-valued property concentrated in areas either with a high frequency of damaging storms (Gulf and East Coast), or to where even a small but intense storm can cause huge losses (urban areas and West Coast). These shifts, plus the continuing growth of population in other storm-prone areas have greatly increased society's vulnerability to storm damage. An in-depth analysis of many conditions was required to establish that the high losses and numerous catastrophes of the 1990s were largely the result of societal changes and not major weather changes. This revised version was published online in June 2006 with corrections to the Cover Date.  相似文献   

13.
This study presents the data on the hydrochemical characteristics and isotope chemistry of Liwa aquifer, which could be useful to clarify the hydrochemical facies and hydrogeological regime in the study area. Electric conductivity and total dissolved solid values show that the investigated water is slightly brackish, due to the effect of evaporation and the occurrences of evaporite rocks in the adjacent Sabkhas of Abu Dhabi. Major cations and anions arranged according to their decreasing concentrations are: Na+ > Ca+2 > K+ > Mg+2 and Cl > HCO3  > SO4−2, respectively. As sodium is the dominate cation and chloride is the prevailing anion, hydrochemically the groundwater of Liwa can be classified as Na–Cl rich, predominantly chloridic. Ion concentrations increase towards the northeast and presumably coincide with the lithological sources of ions. Factors affecting the hydrochemistry of the groundwater of the investigated area include the effect of weathering of soil and rocks, evaporation and agricultural activities. Stable isotopes of oxygen and hydrogen show that the shallow aquifers contain a single water type that originated in a distinct climatic regime. This water type deviates from the local meteoric water line, as well as from the Eastern Mediterranean Meteoric Water Line, suggesting potential evaporation of recharged water prior to infiltration. The waters are poor in tritium, and thus can be considered generally as indication for recharge prior to 1952. The degradation of groundwater quality can be attributed to evaporation and agricultural practices in most cases.  相似文献   

14.
15.
The source region of the Yellow River, located in the northeastern portion of the Qinghai–Tibet Plateau, plays a critical role in water conservation, biodiversity protection, and wetland conservation. Aeolian desertification of this area is an important concern. Remote sensing and GIS technology were employed to assess the trends in aeolian desertification from 1975 to 2005. The monitoring results showed that, aeolian desert land increased from 15,112 to 17,214 km2 during 1975–2005. In addition, it was found that the area of aeolian desertification increased rapidly from 1975 to 1990, was stable from 1990 to 2000, and slightly decreased from 2000 to 2005. Increasing temperature, overgrazing, and drainage of wetlands have been key driving factors of aeolian desertification. Thus, to control the expansion of aeolian desert lands in the source region of the Yellow River and to rehabilitate existing desert areas, the priority should be given to altering human behavior in these areas.  相似文献   

16.
The Malaqet–Mundassah area lies on the western flank of the Northern Oman Mountains in the UAE and Oman. This area is a well-exposed example of Alpine thrusted and folded Ophiolitic assemblage and post-obduction autochthonous sequences. The hinge zones of the thrust propagation folds accommodated stronger deformation compared with the weaker deformation that occurred in the other parts of these folds. In this area, there have been three main tectonic shortening events, two associated with the formation of unconformities (pre-Late Campanian and Cretaceous/Tertiary) and one during the deposition of megabreccia and conglomerates units (Early–Middle Eocene). Each event continued mildly during the deposition of sediments above. Tectonism was accompanied by sea level changes so that the Malaqet–Mundassah area experienced two marine regressions and two transgressions between the Late Cretaceous and the Oligocene times. Activity of northwest striking (NE-dipping) thrust faults and similarly trending thrust-propagation folds is responsible for the formation of a local basin, the Malaqet–El Saah basin in which the Simsima, Muthaymimah, Saah, and Tawi Uwayyir formations of the area were deposited. The syn-sedimentary activity of thrusts, folds and strike-slip faults is documented in thickness variations, stratigraphic onlapping of formations towards the fold hinges, and the presence of megabreccia and conglomerate deposits not found elsewhere in the foreland basin.  相似文献   

17.
We present an analysis of multicolor (U BV RI JH K) observations of the blazar 3C 454.3 made in 2004–2006. We used the light curves compiled at the Turin Observatory from coordinated observations in the framework of the WEBT program. We consider color variations in two time intervals, when an unprecedented strong outburst occurred (2004–2005), and when the object was in a post-eruptive state and a low-amplitude brightness increase was observed (2006). The spectral energy distribution (SED) of the variable component remained the same within each of these intervals, but differed between them. In both cases, this SED followed a power law after correction for extinction, suggesting the variable component has a synchrotron nature. We conclude that the variations in the optical and IR were due to the same variable source. The object’s unusual color behavior (the brighter, the redder) was due to an increasing contribution from a variable component that was redder than the constant component (big blue bump).  相似文献   

18.
Cattle-raising, especially for dairy, has expanded in the Ecuadorian Andes since the late 1990s as smallholding farmers have shifted their livelihood activities away from crop-based agriculture due to changes in climate, market conditions, and rural out-migration. Non-migrants constructing cattle-based livelihoods are turning to cattle as the basis for “viable” livelihoods in order to remain in depopulating rural parishes. Non-migrant farmers express ideals such as autonomy and tranquility as reasons for their attachment to rural places. In turn, their livelihood activities remake these places materially. Drawing on Tim Ingold’s conceptualization of taskscape and landscape, I argue that cattle-based livelihoods create a taskscape prone to human–wildlife conflict. Since 2009, residents have reported dozens of Andean bear attacks on cattle. Cattle are vulnerable capital assets. They represent both an investment with daily and weekly dividends over many years, in the form of milk, and a long-term form of wealth storage. The turn to cattle-based livelihoods in this region has thus heightened human–bear conflict. The phenomenon of the human–bear conflict is therefore a product of shifting livelihoods and accompanying changes in the taskscape. This analysis demonstrates the importance of listening to narratives of place attachment and accounting for the cultural logics of livelihood choices when considering interventions to address human–wildlife conflict.  相似文献   

19.
Doklady Earth Sciences - A statistical analysis of extreme episodes of aridity and humidity for the territory of the Southern Urals was performed. The calculations were based on the average daily...  相似文献   

20.
Escanaba Trough is the southernmost segment of the Gorda Ridge and is filled by sandy turbidites locally exceeding 500 m in thickness. New results from Ocean Drilling Program (ODP) Sites 1037 and 1038 that include accelerator mass spectrometry (AMS) 14C dates and revised petrographic evaluation of the sediment provenance, combined with high-resolution seismic-reflection profiles, provide a lithostratigraphic framework for the turbidite deposits. Three fining-upward units of sandy turbidites from the upper 365 m at ODP Site 1037 can be correlated with sediment recovered at ODP Site 1038 and Deep Sea Drilling Program (DSDP) Site 35. Six AMS 14C ages in the upper 317 m of the sequence at Site 1037 indicate that average deposition rates exceeded 10 m/k.yr. between 32 and 11 ka, with nearly instantaneous deposition of one approximately 60-m interval of sand. Petrography of the sand beds is consistent with a Columbia River source for the entire sedimentary sequence in Escanaba Trough. High-resolution acoustic stratigraphy shows that the turbidites in the upper 60 m at Site 1037 provide a characteristic sequence of key reflectors that occurs across the floor of the entire Escanaba Trough. Recent mapping of turbidite systems in the northeast Pacific Ocean suggests that the turbidity currents reached the Escanaba Trough along an 1100-km-long pathway from the Columbia River to the west flank of the Gorda Ridge. The age of the upper fining-upward unit of sandy turbidites appears to correspond to the latest Wisconsinan outburst of glacial Lake Missoula. Many of the outbursts, or j?kulhlaups, from the glacial lakes probably continued flowing as hyperpycnally generated turbidity currents on entering the sea at the mouth of the Columbia River.  相似文献   

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