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Decadal Seismicity Prior to Great earthquakes at Subduction Zones: Roles of Major Asperities and Low-Coupling Zones

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International Journal of Geosciences 2021年第9期12卷 845-926页

作者： Lynn R. Sykes lamont-doherty earth observatory of columbia university Palisades New York USA

Decadal forerunning seismic activity of magnitude Mw ≥ 5.0 is mapped for all 45 mainshocks of Mw 7.7 to 9.1 at subduction zones of the world from 1993 to mid 2020. The zones of high slip in nearly all great earthquakes were nearly quiescent beforehand and are identified as the sites of great asperities and zones of strong seismic coupling. Much forerunning activity occurred at smaller asperities along the peripheries of the rupture zones of many great and giant mainshocks. Those sizes of great asperities as ascertained from forerunning activity generally agree with the areas of high seismic slip as determined by others from geodetic and tide-gauge data and finite-source seismic modeling. Asperities are strong, well-coupled portions of plate interfaces. Different patterns of forerunning activity on time scales of about 5 to 45 years are attributed to either the sizes and spacing of asperities (or lack of). This permits many great asperities to be mapped decades before they rupture in great and giant shocks. Several poorly coupled subduction zones such as Java, Lesser Sunda, Marianas, Tonga and Kermadec are characterized by few great thrust earthquakes and little, in any forerunning activity. Rupture zones of many great and giant earthquakes are bordered either along strike, updip, or downdip by zones of lower plate coupling. Several bordering regions were sites of forerunning activity, aftershocks, and slow-slip events. The detection of forerunning and precursory activities of various kinds should be sought on the peripheries of great asperities as well as within zones of high co-seismic slip.

关键词： earthquakes Subduction Prediction Plate Coupling Asperities

A Connection between Geometrical Spreading and the Adjoint Field in Travel Time Tomography

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Applied Mathematics 2020年第2期11卷 84-96页

作者： William Menke lamont-doherty earth observatory of columbia university Palisades New York USA

The goal of tomography is to reconstruct a spatially-varying image function s(x,m), where x is position and m is a finite-length vector of parameters. Many reconstruction methods minimize the total L2 error E ≡ eTe, where individual errors ei quantify misfit between predictions and observations, to quantify goodness of fit. So-called adjoint state methods allow the gradient ∂E/∂mi to be computed extremely efficiently from an adjoint field, facilitating image reconstruction by gradient-descent methods. We examine the structure of the differential equation for the adjoint field under the ray approximation and find that it has the same form as the transport equation, whose solution involves the well-known geometrical spreading function R Consequently, as R is routinely tabulated as part of a ray calculation, no extra work is needed to compute the adjoint field, permitting a rapid calculation of the gradient?∂E/∂mi.

关键词： Adjoint State Method Eikonal Equation Geometrical Spreading Gradient-Descent Method Transport Equation Travel Time Tomography

Preliminary study of mollusk fossils in the Qinan Miocene loess-soil sequence in western Chinese Loess Plateau

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Science China earth Sciences 2006年第7期49卷 724-730页

作者： Denis-Didier Rousseau Université Montpellier II Institut des Sciences de l’Evolution (UMR CNRS 5554) Case 61 Place E. Bataillon 34095 Mont-pellier Cedex 05 France Lamont-Doherty Earth Observatory of Columbia University Palisades New York 10964 USA

The first near continuous mollusk fossil record from the Qinan Miocene loess-soil se-quence is presented. Results show that mollusk species are abundant in the QA-I section between 22 and 6.2 Ma, and both loess layers and soil layers yield mollusk fossil individuals. All mollusk species are terrestrial and well preserved in the section. Most species are identical to those identified in the Quaternary loess-soil sequence of the Loess Plateau. The thermo-humidiphilous group generally is distributed in soil layers, whereas cold-aridiphilous group can be observed in loess layers. From the Miocene to Quaternary, the occurrence and divergence of new species of Metodontia and Cathaica correspond to the crucial periods of regional and global environmental changes, indicating that mol-lusk species are sensitive to environmental variations. Preliminary study on the QA-I mollusk record indicates that the Qinan Miocene loess-soil sequence may have a similar sedimentary environment to the Quaternary loess-soil sequence of the Loess Plateau.

关键词： mollusk fossils, Miocene loess, Loess Plateau, mollusk evolution, sedimentary environment.

FAIR Geoscientific Samples and Data Need International Collaboration

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Acta Geologica Sinica(English Edition) 2019年第S01期93卷 32-33页

作者： Kerstin LEHNERT Lesley WYBORN Jens KLUMP lamont-doherty earth observatory Columbia UniversityPalisadesNY10964USA National Computational Infrastructure Facility and Research School of earth Sciences Australian National UniversityCanberra2600ACTAustralia CSIRO ARRC KensingtonWA 6151Australia

1 Introduction The primary goal of the Deep-time Digital earth project is to develop an open collaboration and data sharing platform that enables the transition of deep-time geoscientific research to a Big Data driven *** an open platform will require the ability to effectively and efficiently access and integrate a wide variety of digital earth data.

关键词： FAIR findable accessible interoperable reusable data standards samples IGSN

An intermediate coupled model for the tropical ocean-atmosphere system

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Science China earth Sciences 2018年第12期61卷 1859-1874页

作者： Xunshu SONG Dake CHEN Youmin TANG Ting LIU Ocean College Zhejiang UniversityZhoushan 316021China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyHangzhou 310012China lamont-doherty earth observatory of columbia university New York 10964USA Environmental Science and Engineering University of Northern British ColumbiaPrince George V2N 4Z9Canada

An intermediate ocean-atmosphere coupled model is developed to simulate and predict the tropical interannual variability. Originating from the basic physical framework of the Zebiak-Cane(ZC) model, this tropical intermediate couple model(TICM) extends to the entire global tropics, with a surface heat flux parameterization and a surface wind bias correction added to improve model performance and inter-basin connections. The model well reproduces the variabilities in the tropical Pacific and Indian basins. The simulated El Ni?o-Southern Oscillation(ENSO) shows a period of 3–4 years and an amplitude of about 2°C, similar to those observed. The variabilities in the Indian Ocean, including the Indian Ocean basin mode(IOBM) and the Indian Ocean Dipole(IOD), are also reasonably captured with a realistic relationship to the Pacific. However, the tropical Atlantic variability in the TICM has a westward bias and is overly influenced by the tropical Pacific. A 47-year hindcast experiment using the TICM for the period of 1970–2016 indicates that ENSO is the most predictable mode in the tropics. Skillful predictions of ENSO can be made one year ahead, similar to the skill of the latest version of the ZC model, while a "spring predictability barrier" still exists as in other models. In the tropical Indian Ocean, the predictability seems much higher in the west than in the east. The correlation skill of IOD prediction reaches 0.5 at a 5-month lead, which is comparable to that of the state-of-the-art coupled general circulation models. The prediction of IOD shows a significant "winter-spring predictability barrier", implying combined influences from the tropical Pacific and the local sea-air interaction in the eastern Indian Ocean. The TICM has little predictive skill in the equatorial Atlantic for lead times longer than 3 months, which is a common problem of current climate models badly in need of further investigation.

关键词： Intermediate coupled model ENSO IOD Prediction

Simultaneous detection of flare-associated kink oscillations and extreme-ultraviolet waves

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Science China(Technological Sciences) 2024年第5期67卷 1592-1601页

作者： LI Dong HOU ZhenYong BAI XianYong LI Chuan FANG Matthew ZHAO HaiSheng WANG JinCheng NING ZongJun Key Laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing210023China Yunnan Key Laboratory of the Solar Physics and Space Science Kunming650216China School of earth and Space Sciences Peking UniversityBeijing100871China National Astronomical Observatories Chinese Academy of SciencesBeijing100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing100049China School of Astronomy and Space Science Nanjing UniversityNanjing210023China Key Laboratory of Modern Astronomy and Astrophysics Ministry of EducationNanjing UniversityNanjing210023China Columbus Academy GahannaOhio43230USA Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing100049China Yunnan Observatories Chinese Academy of SciencesKunming650216China

Kink oscillations,which are frequently observed in coronal loops and prominences,are often accompanied by extreme-ultraviolet(EUV)***,much more needs to be explored regarding the causal relationships between kink oscillations and EUV *** this article,we report the simultaneous detection of kink oscillations and EUV waves that are both associated with an X2.1 flare on 2023 March 03(SOL2023-03-03T17:39).The kink oscillations,which are almost perpendicular to the axes of loop-like structures,are observed in three coronal loops and one *** short loop shows in-phase oscillation within the same period of 5.2 min at three *** oscillation could be triggered by the pushing of an expanding loop and interpreted as the standing kink *** lags are found between the kink oscillations of the short loop and two long loops,suggesting that the kink wave travels in different *** kink oscillations of one long loop and the prominence are possibly driven by the disturbance of the coronal mass ejection(CME),and that of another long loop might be attributed to the interaction of the EUV *** onset time of the kink oscillation of the short loop is nearly same as the beginning of an EUV *** fact demonstrates that they are almost *** EUV wave is most likely excited by the expanding loop structure and shows two *** leading component is a fast coronal wave,and the trailing one could be due to the stretching magnetic field lines.

关键词： coronal loops solar flares solar prominence solar oscillations extreme-ultraviolet wave magnetohydrodynamic

Asymmetric variability between maximum and minimum temperatures in Northeastern Tibetan Plateau:Evidence from tree rings

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Science China earth Sciences 2008年第1期51卷 41-55页

作者： Jacoby GORDON Tree-Ring Laboratory Lamont-Doherty Earth Observatory Columbia University NY 10964 USA

Ecological systems in the headwaters of the Yellow River, characterized by hash natural environmental conditions, are very vulnerable to climatic change. In the most recent decades, this area greatly attracted the public's attention for its more and more deteriorating environmental conditions. Based on tree-ring samples from the Xiqing Mountain and A'nyêmagên Mountains at the headwaters of the Yellow River in the Northeastern Tibetan Plateau, we reconstructed the minimum temperatures in the winter half year over the last 425 years and the maximum temperatures in the summer half year over the past 700 years in this region. The variation of minimum temperature in the winter half year during the time span of 1578―1940 was a relatively stable trend, which was followed by an abrupt warming trend since 1941. However, there is no significant warming trend for the maximum temperature in the summer half year over the 20th century. The asymmetric variation patterns between the minimum and maximum temperatures were observed in this study over the past 425 years. During the past 425 years, there are similar variation patterns between the minimum and maximum temperatures; however, the minimum temperatures vary about 25 years earlier compared to the maximum temperatures. If such a trend of variation patterns between the minimum and maximum temperatures over the past 425 years continues in the future 30 years, the maximum temperature in this region will increase significantly.

关键词： Tibetan Plateau tree-ring minimum temperature maximum temperature asymmetric variability warming trend

Castable solid pressure media for multianvil devices

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Matter and Radiation at Extremes 2020年第1期5卷 23-33页

作者： David Walker Jie Li lamont-doherty earth observatory Columbia UniversityPalisades New York 10964USA earth and Environmental Sciences University of MichiganAnn Arbor Michigan 48109USA

Castable solids from Aremco(http://***/potting-casting-materials/)are convenient media for pressure transmission in multianvil geometries of complex shape.A zirconia-based castable ceramic,Aremco Ceramacast 646,is introduced and compared to MgO-Al2O3-SiO2-based Aremco Ceramacast *** 646 has some advantages over the widely used Ceramacast 584;these include ease of consistent fabrication and better thermal *** disadvantages are poorer efficiency in converting press thrust to sample pressure and slower quenching *** applications are informed by these differences.

关键词： ceramic Ceram media

Decoding the inconsistency of six cropland maps in China

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The Crop Journal 2024年第1期12卷 281-294页

作者： Yifeng Cui Ronggao Liu Zhichao Li Chao Zhang Xiao-Peng Song Jilin Yang Le Yu Mengxi Chen Jinwei Dong Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China university of Chinese Academy of Sciences Beijing 100049China Department of Geographical Sciences University of MarylandCollege ParkMD 20740USA College of Grassland Science and Technology China Agricultural UniversityBeijing 100193China Ministry of Education Ecological Field Station for East Asian Migratory Birds Department of Earth System ScienceInstitute for Global Change StudiesTsinghua UniversityBeijing 100084China Ministry of Education Ecological Field Station for East Asian Migratory Birds Beijing 100084China Tsinghua university(Department of earth System Science)-Xi’an Institute of Surveying and Mapping Joint Research Center for Next-Generation Smart Mapping Beijing 100084China Institute of Remote Sensing and Geographic Information System Peking UniversityBeijing 100871China Department of Forest and Conservation Sciences University of British ColumbiaVancouverBCV6T 1Z4Canada

Accurate cropland information is critical for agricultural planning and production,especially in foodstressed countries like *** widely used medium-to-high-resolution satellite-based cropland maps have been developed from various remotely sensed data sources over the past few decades,considerable discrepancies exist among these products both in total area and in spatial distribution of croplands,impeding further applications of these *** factors influencing their inconsistency are also *** this study,we evaluated the consistency and accuracy of six cropland maps widely used in China in circa 2020,including three state-of-the-art 10-m products(i.e.,Google Dynamic World,ESRI Land Cover,and ESA WorldCover)and three 30-m ones(i.e.,GLC_FCS30,GlobeLand 30,and CLCD).We also investigated the effects of landscape fragmentation,climate,and agricultural *** using a ground-truth sample revealed that the 10-m-resolution WorldCover provided the highest accuracy(92.3%).These maps collectively overestimated Chinese cropland area by up to 56%.Up to 37%of the land showed spatial inconsistency among the maps,concentrated mainly in mountainous regions and attributed to the varying accuracy of cropland maps,cropland fragmentation and management practices such as *** work shed light on the promotion of future cropland mapping efforts,especially in highly inconsistent regions.

关键词： Consistency and accuracy 10-and 30 m Cropland mapping Agricultural management China