Statistical analysis of strong-motion accelerograms and its application to earthquake early-warning systems   总被引：2，自引：0，他引：2  

Gunnar Grecksch  Hans-Joachim Kümpel 《Geophysical Journal International》1997,129(1):113-123

In view of increasing damage due to earthquakes, and the current problems of earthquake prediction, real-time warning of strong ground motion is attracting more interest. In principle, it allows short-term warning of earthquakes while they are occurring. With warning times of up to tens of seconds it is possible to send alerts to potential areas of strong shaking before the arrival of the seismic waves and to mitigate the damage, but only if the seismic source parameters are determined rapidly. The major problem of an early-warning system is the real-time estimation of the earthquake's size.
We investigated digitized strong-motion accelerograms from 244 earthquakes that occurred in North and Central America between 1940 and 1986 to find out whether their initial portions reflected the size of the ongoing earthquake. Applying conventional methods of time-series analyses we calculate appropriate signal parameters and describe their uncertainties in relation to the magnitude and epicentral distance. The study reveals that the magnitude of an earthquake can be predicted from the first second of a single accelerogram within ±1.36 magnitude units. The uncertainty can be reduced to about ±0.5 magnitude units if a larger number (≥8) of accelerograms are available, which requires a dense network of seismic stations in areas of high seismic risk.  相似文献   

Comparative study of the Ferranti,Honeywell and Litton inertial surveying systems testnet Ebersberger Forst     

Caspary  W. F.  König  R. 《Journal of Geodesy》1986,60(2):143-153

In order to assess the accuracy, reliability and efficiency of current inertial surveying systems a joint project has been started at the University of the Bundeswehr Munich. As a part of this project the testnet Ebersberger Forst has been established. It consists of 60 monumented points located at cross-roads in a flat area and it makes up a grid pattern of6 N-S and9 E-W traverses with a spacing of1–2 km. The points are determined by classical surveying techniques with a standard deviation of less than1 cm forE, N andH. Observation campaigns were carried through with a Ferranti, a Honeywell and a Litton system. Each campaign consisted of three independent missions performed under identical observation schemes. The preliminary evaluation of the data sets leads to standard deviations of between8 and16 cm for each coordinate if determined in a single mission with a Honeywell or Litton system. The correlations along a traverse follow approximately the series ρ, ρ², ρ³, ... with ρ⋟0.9. Cross correlation is only present betweenE orN, respectively, andH. The positions observed with the Ferranti system are less accurate, which might be explainable by the applied software and by two gross input errors during the missions. A rigorous post-mission adjustment of the data considerably improved the results.  相似文献   

Eclogites from the Chinese continental scientific drilling borehole, their petrology and different P-T evolutions   总被引：1，自引：0，他引：1  

Yong-Feng  Zhu  Hans-Joachim  Massonne  Thomas  Theye 《Island Arc》2007,16(4):508-535

Abstract Four phengite‐bearing eclogites, taken from different depths of the Chinese continental scientific drilling (CCSD) borehole in the Sulu ultrahigh pressure terrane, eastern China, were studied with the electron microprobe. The compositional zonations of garnet and omphacite are moderate, whereas phengite compositions generally vary significantly in a single sample from core to rim by decrease of the Si content. Various geothermobarometric methods were applied to constrain the P‐T conditions of these eclogites on the basis of the compositional variability of the above minerals. The constrained P‐T path for sample B218 is characterized by pressure decrease from ca 3.0 GPa (ca 600°C) to 1.3 GPa (ca 550°C). Eclogite B310 yielded P‐T conditions of 3.0 GPa and 750°C. The path for eclogite B1008 starts at about 650°C and 3.6–3.9 GPa (stage I) followed by a pressure decrease to 2.8–3.0 GPa and a significant temperature rise (stages II and IIIa, 750–810°C). Afterwards, this rock cooled down to 620–660°C at still high pressures (2.5–2.7 GPa, stage IIIb). Retrograde conditions were about 670°C and 1.3 GPa (stage IV). Eclogite B1039 yielded a P‐T path starting at ca 600°C and 3.3–3.9 GPa (stage I). A pressure decrease to about 3.0 GPa (stage II, 590–610°C) and then a moderate isobaric temperature increase to ca 630°C (stage III) followed. Stage IV is characterized by temperatures of 650°C at pressures close to 1.3 GPa. During and after this stage (hydrous) fluids partially rich in potassium penetrated the rocks causing minor changes. Relatively high oxygen fugacities led to andradite and magnetite among the newly formed minerals. We think that the above findings can be best explained by mass flow in a subduction channel. Thus, we conclude that the assembly of UHP rocks of the CCSD site, eclogites, quartzofeldspathic rocks, and peridotites, cannot represent a crustal section that was already coherent at UHP conditions as it is the common belief currently. The coherency was attained after significant exhumation of these UHP rocks.  相似文献   

海洋双壳类软体动物幼虫发育类型及其在东太平洋的地理分布     

刘春莲  杨建林  白雁 《海洋通报》2002,21(3):19-26

沿东太平洋浅海分布的双壳类软体动物数据显示,大量非浮游异养型双壳类具有广泛的地理分布.其中某些种的纬度跨度可达30°以上,这些种绝大部分是分布在38°N～5°S之间.东太平洋沿岸海流、热带海洋相对适宜的环境以及生物地理分区性是导致这一现象的主要原因.经历浮游异养型幼虫发育阶段的双壳类一般具有较高的地理散布潜力,但是,其中某些种由于其对环境的忍耐性较差,只能局限于狭窄的分布范围.东太平洋浅海双壳类的种多样性以及非浮游异养型与浮游异养型双壳类的比例随纬度发生变化.低纬度地区显示很高的多样性,向高纬度地区逐渐降低,浮游异养型双壳类的下降率大大高于非浮游异养型.热带地区以浮游异养型双壳类占主导地位,随着纬度增加其所占比例减少,而非浮游异养型双壳类的比例随纬度增加而逐渐提高.表明随纬度增加所发生的环境变化对浮游异养型双壳类的影响更为显著,而对以本身卵黄为幼虫营养来源的非浮游异养型双壳类影响相对较小一些.  相似文献   

A stock rebuilding algorithm featuring risk assessment and an optimization strategy of single or multispecies fisheries     

Groger  Joachim P.; Rountree  Rodney A.; Missong  Martin; Ratz  Hans-Joachim 《ICES Journal of Marine Science》2007,64(6):1101-1115

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Stock structure of Atlantic cod (Gadus morhua) in West Greenland waters: implications of transport and migration     

Storr-Paulsen  Marie; Wieland  Kai; Hovgard  Holger; Ratz  Hans-Joachim 《ICES Journal of Marine Science》2004,61(6):972-982

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Long-term variability of growth and recruitment of cod (Gadus morhua) off Greenland   总被引：1，自引：0，他引：1  

Ratz  Hans-Joachim; Lloret  Josep 《ICES Journal of Marine Science》2005,62(7):1310-1321

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Provenance of Cretaceous clastics in the Subhercynian Basin: constraints to exhumation of the Harz Mountains and timing of inversion tectonics in Central Europe     

Hilmar von Eynatten  Thomas Voigt  Angela Meier  Hans-Joachim Franzke  Reinhard Gaupp 《International Journal of Earth Sciences》2008,97(6):1315-1330

The Harz Mountains and the adjacent Subhercynian Cretaceous Basin figure as the most prominent surface representative for Late Cretaceous inversion structures in Central Europe. Facies, depositional architecture and provenance of the basin fill reflect mechanisms and timing of the exhumation of the Harz. From Hauterivian to Early Santonian there is no evidence for detrital input from the nearby Harz area. Sediments are mature quartzarenites derived from Paleozoic basement rocks and/or recycled Permian to Mesozoic sedimentary rocks. This situation changed drastically in Middle to Late Santonian when freshly exhumed and eroded Mesozoic sedimentary cover rocks of the Harz were delivered into the basin. Feldspar and lithoclasts reflect erosion of Triassic and, in places, Jurassic to Turonian strata. Apatite and garnet in heavy mineral spectra are derived from largely unweathered Lower Triassic Buntsandstein as indicated by apatite and garnet chemistry. In Early Campanian, Paleozoic lithoclasts indicate erosion cutting down into the basement of the Harz. Simultaneous strong decrease of feldspar, garnet and apatite suggest an almost complete removal of the 2–3 km thick Mesozoic cover of the Harz within only 2–4 Myr. This translates into an exhumation rate of approximately 1 mm/a consistent with apatite fission track data from granitoid rocks of the Harz Mountains.  相似文献   

Buchbesprechungen     

Hans-Joachim Felber 《Astronomische Nachrichten》1997,318(3):172-172

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Molecular isotopic evidence of environmental and ecological changes across the Cenomanian–Turonian boundary in the Levant Platform of central Jordan     

Julio Sepúlveda  Jens Wendler  Arne Leider  Hans-Joachim Kuss  Roger E. Summons  Kai-Uwe Hinrichs 《Organic Geochemistry》2009,40(5):553-568

We evaluated the structure of planktonic communities and paleoenvironmental conditions throughout the Cenomanian–Turonian Oceanic Anoxic Event (OAE2) by studying bulk geochemical properties and the molecular isotopic composition of source-specific hydrocarbons from organic-rich sediments deposited in an intrashelf basin at the Levant Platform, central Jordan. High concentrations of desmethyl and 4-methylsteranes as well as dinosteranes indicate that marine algae including dinoflagellates were the main primary producing organisms. The presence of 2-methylhopanes and ¹³C-enriched hopanes, in addition to isotopically enriched aryl isoprenoids, evidenced the contribution of cyanobacteria and green sulfur bacteria, respectively. Additionally, variable but fairly low δ¹⁵N values during OAE2 suggest the occurrence of diazotrophy as a likely important process fueling primary production during OAE2 in this stratified/anoxic continental platform. Variations in the relative contribution of biomarkers revealed changes in planktonic communities associated with sea level change and water column stratification. OAE2 was characterized by strong stratification, anoxic bottom waters and a deep chemocline, as evidenced by high gammacerane and homohopane indices and the absence of photic zone euxinia (PZE) markers, respectively. However, the presence of isorenieratane and its derivatives in post-OAE black shales points to a shoaling of the chemocline and to PZE. This interval was also characterized by an exceptionally high abundance of chlorophyll-derived pristane and phytane (up to 2 mg g^?1 TOC), likely as a result of highly enhanced primary production and organic matter preservation. Remarkably, this high productivity event co-occurs with an exceptionally high abundance of calcispheres reported elsewhere to be part of a global bio-event.  相似文献