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Decadal Forecasts of Large earthquakes along the Northern San Andreas Fault System, California: Increased Activity on Regional Creeping Faults Prior to Major and Great Events

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International Journal of Geosciences 2024年第2期15卷 204-230页

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

The three largest earthquakes in northern California since 1849 were preceded by increased decadal activity for moderate-size shocks along surrounding nearby faults. Increased seismicity, double-difference precise locations of earthquakes since 1968, geodetic data and fault offsets for the 1906 great shock are used to re-examine the timing and locations of possible future large earthquakes. The physical mechanisms of regional faults like the Calaveras, Hayward and Sargent, which exhibit creep, differ from those of the northern San Andreas, which is currently locked and is not creeping. Much decadal forerunning activity occurred on creeping faults. Moderate-size earthquakes along those faults became more frequent as stresses in the region increased in the latter part of the cycle of stress restoration for major and great earthquakes along the San Andreas. They may be useful for decadal forecasts. Yearly to decadal forecasts, however, are based on only a few major to great events. Activity along closer faults like that in the two years prior to the 1989 Loma Prieta shock needs to be examined for possible yearly forerunning changes to large plate boundary earthquakes. Geodetic observations are needed to focus on identifying creeping faults close to the San Andreas. The distribution of moderate-size earthquakes increased significantly since 1990 along the Hayward fault but not adjacent to the San Andreas fault to the south of San Francisco compared to what took place in the decades prior to the three major historic earthquakes in the region. It is now clear from a re-examination of the 1989 mainshock that the increased level of moderate-size shocks in the one to two preceding decades occurred on nearby East Bay faults. Double-difference locations of small earthquakes provide structural information about faults in the region, especially their depths. The northern San Andreas fault is divided into several strongly coupled segments based on differences in seismicity.

关键词： San Andreas and Hayward Faults California Fault Creep Forecasts Double-Difference Relocations

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Applying earth Observation Technologies to Economic Consequence Modeling:A Case Study of COVID‑19 in Los Angeles County,California

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International Journal of Disaster Risk Science 2024年第1期15卷 18-31页

作者： Fynnwin Prager Marina T.Mendoza Charles K.Huyck Adam Rose Paul Amyx Gregory Yetman Kristy F.Tiampo California State university Dominguez HillsCarsonCA 90747USA ImageCat Inc.Long BeachCA 90802USA university of Southern California Los AngelesCA 90015USA CIESIN–Center for International earth Science Information Network Columbia UniversityPalisadesNY 10964USA Cooperative Institute for Research in Environmental Sciences(CIRES) University of Colorado BoulderBoulderCO 80309USA

earth observation(EO) technologies,such as very high-resolution optical satellite data available from Maxar,can enhance economic consequence modeling of disasters by capturing the fine-grained and real-time behavioral responses of businesses and the *** investigated this unique approach to economic consequence modeling to determine whether crowd-sourced interpretations of EO data can be used to illuminate key economic behavioral responses that could be used for computable general equilibrium modeling of supply chain repercussions and resilience *** applied our methodology to the COVID-19 pandemic experience in Los Angeles County,California as a case *** also proposed a dynamic adjustment approach to account for the changing character of EO through longer-term disasters in the economic modeling *** found that despite limitations,EO data can increase sectoral and temporal resolution,which leads to significant differences from other data sources in terms of direct and total impact *** findings from this analytical approach have important implications for economic consequence modeling of disasters,as well as providing useful information to policymakers and emergency managers,whose goal is to reduce disaster costs and to improve economic resilience.

关键词： Computable general equilibrium models COVID-19 Disaster economic impacts earth observation Economic consequence analysis Los Angeles County

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UPPER OCEAN RESPONSE TO SURFACE MOMENTUM AND FRESHWATER FLUXES IN THE WESTERN PACIFIC WARM POOL

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热带海洋学报 2004年第6期23卷 1-15页

作者： Dake Chen lamont-doherty earth observatory of columbia university Palisades New York

A series of numerical experiments are carried out to study the tropical upper ocean response to combined momentum and buoyancy forcing, with emphasis on the three-dimensional thermohaline structure in the western Pacific warm pool. In response to climatological winds, heat fluxes and freshwater input, the model is able to simulate the salient dynamic and hydrographic features of the tropical Pacific Ocean and their seasonal variability. In response to idealized episodic westerly wind bursts and rainfall, the simulated upper ocean conditions compare favorably with available observations, thus enabling us to identify important physical processes involved. Local forcing, vertical mixing and meridional advection dominate the salt and heat budgets in the warm pool on short time scales, but it is necessary to include the saline water coming from the east with the South Equatorial Current to close the salt budget on seasonal and longer time scales. Strong westerly wind bursts generate a swift eastward equatorial jet and a pair of meridional circulation cells with convergence at the equator. This results in an equatorward advection of relatively fresh water from the north and a depression of the thermocline at the equator. Heavy rainfall reduces the surface mixed layer depth by creating a shallow halocline, thus trapping the momentum and heat inputs near the surface. The remote influences of the episodic momentum and buoyancy fluxes are very different. Westerly wind bursts can generate large downstream disturbances in both dynamic and thermal fields through the propagation of equatorial waves, while the effect of rainfall is mostly confined to the forcing area.

关键词： freshwater flux westerly wind burst western Pacific warm pool

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Global warming: Take action or wait?

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Chinese Science Bulletin 2006年第9期51卷 1018-1029页

作者： W. S. Broecker lamont-doherty earth observatory of columbia university 61 Route 9W/PO Box 1000 Palisades NY 10964-8000 USA

A serious split in opinion exists with re- gard to how to deal with the ongoing buildup of CO2 in our atmosphere. One group contends that, until the warming has more clearly expressed itself, we should put off costly actions. The other group contends that, even if we were to take immediate action, the buildup of CO2 is likely to reach an unacceptable level. Hence action must not be delayed. I stand with the second group. My opinion has been molded by the failure of model simulations to yield the impacts anywhere near as large as those attributable to orbital cycles, to ocean reorganizations, or to solar irradiance. These impacts are well documented in the paleoclimate record. This suggests to me that the models lack important feedbacks and amplifiers present in the real world. Hence they are more likely to underesti- mate the impacts of CO2 than overestimate them as the critics contend. The world’s energy consumption will continue to rise. Because it is so cheap and so abundant, coal will dominate as a supplier. It is also my opinion that CO2 capture and burial will have to play a key role in the struggle to bring the CO2 rise to a halt. Fortunately, it appears that capture and burial are technically and economically feasible. The big question is whether the world can come together and make this happen before CO2 has reached an un- acceptable level.

关键词：全球变暖二氧化碳古气候环境保护温室气体

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Global distribution of geothermal gradients in sedimentary basins

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Geoscience Frontiers 2023年第6期14卷 478-495页

作者： Folarin Kolawole Jonathan C.Evenick lamont-doherty earth observatory at columbia university New YorkNYUSA INPEX Corporation TokyoJapan

The heat budget of sedimentary basins is determined by heat transfer across the lithosphereasthenosphere boundary and lithospheric heat sources,such that the tectonic evolution of their host continental and oceanic lithosphere ultimately impact the present-day heat flow and average geothermal *** increase in availability of publicly-accessible geothermal gradient measurements across the world provides an opportunity to globally assess the dominant controls on the thermal regime of sedimentary ***,we compile a global dataset of152,000 unique data points with constrained bottomhole temperature measurements and assess the relationships between geothermal gradient and selected independent tectonic variables,including crustal and lithospheric thicknesses,crustal age,sediment thickness,and basin *** results show that in both oceanic and continental settings,geothermal gradients exhibit a non-linear,systematic variation with the tectonic *** find that oceanic geothermal gradients decrease with increasing crustal age and lithospheric *** gradients in the continents show no clear relationships with thermotectonic crustal age,but decrease with increasing crustal and lithospheric *** drop significantly at 1.5 km sediment-cover thickness,likely reflecting the effect of high sedimentation rates,but show a striking rise at>12 km thicknesses,potentially influenced by thinned lithosphere and thermal blanketing *** commonly-assumed‘normal’gradient of 25℃/km for continents is only valid for a narrow range(1.5–12.5 km)of sedimentary cover-thickness,and oceanic‘normal’gradient may be as high as 50–75℃/km for>20 Ma crustal age and>50 km-thick *** show that,conditionally,crustal age may best predict average geothermal gradients in oceanic settings,and lithosphere thickness in ***,we observe that tectonic basin types exhibit distinct ranges of gradients that reflect their prevalent tec

关键词： Geothermal gradient Oceanic crust Continental crust Lithosphere Tectonics

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Rock varnish microlaminations from northern Tianshan, Xinjiang and their paleoclimatic implications

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Chinese Science Bulletin 2000年第4期45卷 372-376页

作者： ZHOU Bengang LIU Tanzhuo ZHANG Yuming Institute of Geology Chinese Seismological BureauBeijing 100029China lamont-doherty earth observatory of columbia university PalisadesNY10964USA

Laterally continuous dark and orange microlaminations are observed in rock varnish from the northern Tianshan, Xinjiang. Microprobe chemical analyses indicate that dark layers in the varnish are rich in Mn and orange layers are poor in Mn. Microscopic examinations of varnish ultra-thin sections reveal a lamination pattern that is regionally consistent and comparable. Based on geomorphic age control, the Holocene varnish lamination sequence is tentatively established and its paleoclimatic implications are explored within the framework of existing paleoclimatic data in the region.

关键词： northern Tianshan rock varnish microlaminations.

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Frontsand strong currents of the upper southeast Indian Ocean

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Acta Oceanologica Sinica 2006年第2期25卷 1-24页

作者： HE Zhigang DONG Zhaoqian YUAN Xiaojun Department of Oceanography Xiamen University Xiamen 361005 China Polar Research Institute of China Shanghai 200136 China lamont-doherty earth observatory Columbia University Palisades New York NY 10964-800 USA

Hydrographic data, ADCP velocity and sea level anomaly derived from the satellite altimeter have been jointly analyzed in the southeast lndian Ocean. Results show the locations and orientations of the major oceanic fronts as well as the characteristics of the currents within these fronts in the area. Double subtropical fronts are observed in the section along 120°E, which conflicts with the frontal structure frequently observed before the North Subtropical Front （NSTF） and South Subtropical Front （SSTF） merge into a single STF between 110°-115°E. The Subantarctic Front （SAF）, influenced by the out-of-phase double eddies, runs across 48°S three times between 120° and 127°E. The surface current within the SAF is strengthened up to 105.4 cm/s by the geostrophic effect of these eddies. Furthermore eddies may cause the strong current to split up into two branches within the SAF. The SAF and the primary polar front （PFI） can be identified individually in the ADCP data with a separation distance of about 0.3° at latitude between 140° and 145°E, although they cannot be identified separately in the low-resolution hydrographic data. The different thcrmohaline characteristics of Circumpolar Deep Water （CDW） and Modified Circumpolar Deep Water （MCDW） result in the formation of Southern Antarctic Circumpolar Current Front （SACCF） in the southeast Indian Ocean. It consistently turns northward along the east flank of the Kerguclen Plateau after it runs through the Princess Elizabeth Trough and turns southward sharply north of 60°S with a little seasonal variations. It is shown that the locations and orientations of the SAK the primary PF and SACCF in the ACC of the southeast Indian Ocean can be identified more precisely by the current distribution derived from ADCP data than by hydrographic data, because these fronts are usually accompanied by strong currents. However, the locations and orientations of the STF and the secondary PF are more difficult to be identified through cur

关键词： southeast Indian Ocean front jet

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Observations of the Karimata Strait througflow from December 2007 to November 2008

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Acta Oceanologica Sinica 2013年第5期32卷 1-6页

作者： SUSANTO R Dwi WEI Zexun ADI Rameyo T FAN Bin LI Shujiang FANG Guohong lamont-doherty earth observatory Columbia University First Institute of Oceanography State Oceanic Administration Agency for Marine and Fisheries Research and Development

In order to quantitatively estimate the volume and property transports between the South China Sea and Indonesian Seas via the Karimata Strait, two trawi-resistant bottom mounts, with ADCPs embedded, were deployed in the strait to measure the velocity profile as part of the South China Sea-Indonesian Seas trans- port/exchange （SITE） program. A pair of surface and bottom acoustic modems was employed to transfer the measured velocity without recovering the mooring. The advantage and problems of the instruments in this field work are reported and discussed. The field observations confirm the existence of the South Chi- na Sea branch of Indonesian throughflow via the Karimata Strait with a stronger southward flow in boreal winter and weaker southward bottom flow in boreal summer, beneath the upper layer northward （reversal） flow. The estimate of the averaged volume, heat and freshwater transports from December 2007 to March 2008 （winter） is （-2.7±1.1）×10^6 m^3/s, （-0.30±0.11） PW, 2008 （summer） is （1.2±0.6）×10^6 m^3/s, （0.14±0.03） PW, （-0.18±0.07） × 106 m3/s and from May to September （0.12±0.04）×10^6 m^3/s and for the entire record from December 2007 to October 2008 is （-0.5±1.9）×10^6 m^3/s, （-0.05±0.22） PW, （-0.01±0.15）×10^6 m^3/s （nega- tive/positive represents southward/northward transport）, respectively. The existence of southward bottom flow in boreal summer implies that the downward sea surface slope from north to south as found by Fang et al. （2010） for winter is a year-round phenomenon.

关键词： Karimata Strait transport Indonesian throughflow ADCP measurement acoustic modem

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Interaction of western-Pacific tropical cyclones with El Nio diversity

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National Science Review 2018年第6期5卷 803-804页

作者： Dake Chen Tao Lian State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography lamont-doherty earth observatory of columbia university

Tropical cyclones (TCs) and El NioSouthern Oscillation (ENSO) are both high-impact phenomena, and their interaction is a subject of great scientific interest and practical importance. It is now widely accepted that ... 详细信息

关键词： El Interaction of western-Pacific tropical cyclones with El Ni o diversity

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The ocean's role in climate variability

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Acta Oceanologica Sinica 2008年第Z1期27卷 1-8页

作者： CHEN Dake State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography State Oceanic Administra-tion Hangzhou 310012 China lamont - doherty earth observatory of columbia university Palisades New York USA

Because of its vast volume and heat capacity, the ocean contains most of the memory of the earth's ocean-atmosphere coupled system. It has been suggested that the ocean may delay global warming by absorbing large amounts of heat, that it may cause abrupt climate change due to its disrupted thermohaline circulation, and that it may set the time-scales for various climate oscillations. Although the slow pace and persistence of oceanic variations give hope to long-range prediction, there still exist large uncertainties in climate predictability. Presently available observations and models are generally inadequate for studying and predicting long-term climate changes. However, some short-term fluctuations such as ENSO have been well studied and shown to be highly predictable even with simplified models.

关键词： ocean climate variability predictability.

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