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91.
On 3 December 1828 at half past six in the evening, the border region between Belgium and Germany was stricken by a moderate earthquake. Up to now, the available information on this event has been essentially provided by a few contemporaneous scientific studies. To better evaluate its impact, location and magnitude, we have searched for new original historical reports. We collected 57 additional witness testimonies, which complete those previously collected about the earthquake effects. Among the testimonies, we also retrieved a questionnaire sent by the Prussian government to local authorities with the purpose of quickly obtaining information on the earthquake effects in the western part of the kingdom of Prussia. This inquiry is the oldest of its kind that has been discovered to date in this part of Europe, suggesting a rare concern by a national authority about the seismic hazard, and prefiguring the seismic inquiries that scientific institutions use today. The analysis of these new data made it possible to evaluate the intensity in 50 cities out of the 75 where the earthquake was observed. From these intensity data, we determine that the epicentre was in the Hautes-Fagnes region [lat. 50.38°N/long. 6.19°E?±?30 km] where moderate damage, corresponding to EMS-98 intensity VI–VII, was observed. At large distances, the earthquake was felt as far as Düsseldorf to the north, Brussels to the west, Metz to the south and Wiesbaden to the east. These distances correspond to a perceptibility radius of about 150 km. The magnitude of this earthquake is evaluated to be ML?=?4.7 (?0.2/+0.5) and MW?=?4.2 (+0.4/?0.2). 相似文献
92.
93.
Temporal and spatial information on land use/cover is a prerequisite for effective planning decisions in the context of social and economic development. Satellite remote sensing data have become increasingly important in the study of land use/cover changes. This paper uses multitemporal satellite data to measure and spatially characterize land use/cover changes in the Jaffna Peninsula, northern Sri Lanka over the two decades from 1984 to early 2004 in terms of potential drivers. Over this period, the Jaffna Peninsula has been impacted severely by armed conflict between the government of Sri Lanka and the Liberation Tigers of Tamil Eelam. A postclassification method is used to compare land use/cover classes from satellite images using Geographical Information Systems (GIS) to analyze the spatial pattern of land use/cover changes over the study period. Results indicate that the land use/cover pattern has been very dynamic since early the 1980s, showing a remarkable decrease in agricultural land use and concomitant increase in non-agricultural land uses. The ethnic conflict and its consequences, particularly large-scale population migrations, have been the main driving forces for such land use/cover changes in the Jaffna Peninsula. The results of this study are not only important in aiding efforts to reconstruct this area after decades of physical and socioeconomic devastation, but should also prompt similarly urgent studies in other inaccessible war-torn areas of the world. 相似文献
94.
F.J. García-Tortosa P. Alfaro J. Galindo-Zaldívar L. Gibert A.C. Lpez-Garrido C. Sanz de Galdeano M. Urea 《Geomorphology》2008,97(3-4):374-391
The present work investigates a mountain front within the Plio-Quaternary deposits belonging to the sedimentary fill of the Guadix-Baza Basin (Betic Cordillera, Southern Spain). This 30 km-long front, developed in soft sediments and within a context of high erosion, is generated by the recent activity of the Baza Normal Fault. The mountain front is the natural limit between the western and eastern sectors, corresponding to the two sub-basins of Guadix and Baza. The two main glacis described in previous works in the area of the Baza Fault – the Old Glacis in the Guadix Sub-basin and the Recent Glacis in the Baza Sub-basin – are interpreted here as a single one, displaced by the fault. Using this Glacis as a marker we deduced that its age and the transition of the basin from endorheic to exorheic must be much older than previous estimations. The Baza Fault may be considered as one of the most active faults of the central part of the Betic Cordillera, according to the results of the general quantitative analysis of the mountain front relief using the Smf/Vf ratio and the SL index. 相似文献
95.
96.
Elisabeth Dologlou 《Acta Geophysica》2008,56(4):1015-1024
A 12-year period experimental data, from 1 January 1995, to 20 August 2007, have been examined for possible correlations between Seismic Electric Signals (SES) of the VAN method and source parameters of the corresponding earthquakes in Western Greece. During that period 13 earthquakes of magnitude M W ≥ 5 with epicenters in the area 19–24°E, 36–41°N and available the CMT solutions (Centroid Moment Tensor focal mechanism solutions) have been found to be preceded by a SES each time at one of the three VAN stations of IOA, PIR or PAT. The results of IOA and PIR stations are compared to those reported by Uyeda et al. 1999, for the previous period 1983–1994. The IOA station seems to be sensitive to earthquakes with thrust type mechanisms being mainly consistent to its past behavior. The PIR station, which is moved from its previous position by few kilometers, exhibits some changes. It detects now both strike slip and thrust type earthquakes and becomes sensitive to new areas indicating probably the strong dependence of the SES station detection ability upon its location. 相似文献
97.
Study of a longshore transect off Southern California suggests that the length scales (22 to 27 km) of phytoplankton species patches may be related to those of low-frequency currents. The patch boundaries were independent of shelf width but they were probably not independent of changes in chlorophyll fluorescence, temperature, and bottom topography. 相似文献
98.
A sequence of 25 bread-kiln floors was sampled for archaeomagnetic measurements in a bakehouse in the old town of Lübeck, Germany. Due to archaeological dating this kiln floor sequence has been built up presumably from the late 13
th
to the 18
th
century. The primary magnetisation component is carried by magnetite (maghemite) and is very stable. Small viscous magnetisation components could be removed easily. The preliminary results of characteristic remanent magnetisation for 23 of the kiln-floor layers show clearly the trend of the geomagnetic secular variation expected for that time interval. By comparison with French and British master curves, the kiln-floor sequence started around 1425 and lasted until 1775 AD. Presently, confidence circles are relatively large and need refineing by measuring more samples, which have already been collected. Together with
14
C dating that can be determined from the charcoals found in the lowest layers and thermoluminescence dating of the layers, we expect to obtain, for the first time, a secular variation curve for Northern Germany covering the time interval from 1400 to 1800 years AD. 相似文献
99.
Recurrent climate hazards challenge subsistence farmers in developing countries. Reliance on various diversification strategies and traditional risk sharing among kin and families has serious limitations, such as the problem of covariate risk within such networks. Index-based crop insurance could help to reduce people's climate-related risk, but raising the necessary capital to make insurance schemes financially secure is difficult for micro-insurance providers. We examine the extent to which spatial pooling of micro-insurance schemes could reduce these capital requirements. We simulate a hypothetical insurance market operating in Ethiopia, using rainfall data and yield estimates for 15 stations. By performing a Monte Carlo analysis, risk capital required to keep the probability of financial ruin below a threshold value is identified. We investigate the marginal benefits of pooling increasing numbers of sites, as well as the relationship between the benefits of pooling and the spatial covariance of rainfall. We find spatial diversification to offer considerable savings in required capitalization with as few as three sites pooled, as well as a weak but significant relationship between rainfall covariance and those benefits. The results suggest that spatial pooling may be an attractive option for micro-insurers, worthy of a detailed case-by-case analysis when designing index-insurance schemes. 相似文献
100.
Elisabeth Blanc 《Comptes Rendus Geoscience》2010,342(4-5):312-322
Sprites, jets and elves called Transient Luminous Events (TLE), observed in the middle and upper atmosphere above thunderstorms, are the manifestation of intense energy exchanges between the troposphere, stratosphere and mesosphere. Different types of luminous emissions have been identified by ground-based observations, showing the complexity of these phenomena. Space missions showed that transient emissions in the Earth atmosphere are very broad including Radio Frequency (RF), IR to FUV radiations and X-gamma ray emissions called Terrestrial Gamma Flashes (TGF) with energies reaching 30 Mev. However, there are no global observations of these events together. This paper reviews space observations performed up to now and emphasizes the challenges of the future space missions in global measurements of all possible emissions together for the understanding of the physical mechanisms at the origin of these phenomena and their effects on the Earth environment. 相似文献