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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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Influence of self-similar stresses on scenario earthquake construction:An example along the Tanlu Fault

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Science China earth Sciences 2024年第5期67卷 1687-1697页

作者： Feng HU Huajian YAO Houyun YU Zeyu LU Jieyi HOU Song LUO Zhigang SHAO Xiaofei CHEN School of earth and Space Sciences University of Science and Technology of ChinaHefei 230026China Mengcheng Geophysical National Field Scientific observatory Hefei 230026China Department of earth and Space Science Southern University of Science and TechnologyShenzhen 518055China Institute of earthquake Prediction China Earthquake AdministrationBeijing 100036China

As a famous deep and large fault in eastern China,the Tanlu Fault passes through Anhui,Jiangsu,and Shandong and into northeastern *** is important to improve the understanding of seismic hazard assessments in areas near *** start a scenario earthquake simulation in the M7.5 earthquake potential area of the Xinyi-Sihong segment of the Tanlu *** fault rupture length and width are constrained according to the scaling law of large intraplate earthquakes,the background normal stress is depth dependent,and the initial shear stresses are determined using trial and error by matching the earthquake *** the 120 km rupture length of the M7.5 earthquake,we compare the horizontal uniform stress model and self-similar stress perturbation *** findings reveal that the seismic source time function of the horizontal uniform stress model is similar to that of the Haskell model and that of the self-similar stress perturbation model is more similar to that of a real earthquake *** compare the dynamic rupture simulation and ground motion results under four different stress conditions and find that the shorter the characteristic length of the self-similar function is,the rougher the initial *** the M7.5earthquake with an epicenter in the vicinity of Suqian,the Xinyi-Tancheng segment,which is located in the IX-intensity zone north of the epicenter,vibrates more strongly on the northern side than on the southern side due to the influence of the lowvelocity zone and the peak slip *** response spectra analysis at stations in the study area is useful for improving the earthquake resistance capability.

关键词： Scenario earthquakes Self-similar stress Tanlu Fault Dynamic rupture Ground motion

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A virtual thermometer for ultrahigh-temperature-pressure experiments in a large-volume press

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Matter and Radiation at Extremes 2024年第4期9卷 98-110页

作者： Bingtao Feng Longjian Xie Xuyuan Hou Shucheng Liu Luyao Chen Xinyu Zhao Chenyi Li Qiang Zhou Kuo Hu Zhaodong Liu Bingbing Liu State Key Laboratory of Superhard Materials Synergetic Extreme Condition User FacilityCollege of PhysicsJilin UniversityChangchun 130012China Department of earth Sciences University College LondonLondon WC1E 6BSUnited Kingdom earth and Planetary Laboratory Carnegie Institute for ScienceWashingtonDistrict of Columbia 20015USA College of earth Sciences Jilin UniversityChangchun 130012China

Ultrahigh-temperature-pressure experiments are crucial for understanding the physical and chemical properties of *** recent development of boron-doped diamond(BDD)heaters has made such melting experiments possible in large-volume ***,estimates of temperatures above 2600 K and of the temperature distributions inside BDD heaters are not well constrained,owing to the lack of a suitable ***,we establish a three-dimensional finite element model as a virtual thermometer to estimate the temperature and temperature field above 2600 *** advantage of this virtual thermometer over those proposed in previous studies is that it considers both alternating and direct current heating modes,the actual sizes of cell assemblies after compression,the effects of the electrode,thermocouple and anvil,and the heat dissipation by the pressure-transmitting *** virtual thermometer reproduces the power-temperature relationships of ultrahigh-temperature-pressure experiments below 2600 K at press loads of 2.8-7.9 MN(~19 to 28 GPa)within experimental *** temperatures above 2600 K predicted by our virtual thermometer are within the uncertainty of those extrapolated from power-temperature relationships below 2600 ***,our model shows that the temperature distribution inside a BDD heater(19-26 K/mm along the radial direction andearth and material sciences.

关键词： virtual ultrahigh sizes

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Response of InSight resonance modes to environmental factors on Mars

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earth and Planetary Physics 2024年第4期8卷 579-588页

作者： LiFei Tian HuaJian Yao Laboratory of Seismology and Physics of earth’s Interior School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230026China Chinese Academy of Sciences Center for Excellence in Comparative Planetology University of Science and Technology of ChinaHefei 230026China Mengcheng National Geophysical observatory University of Science and Technology of ChinaMengcheng 230026China

The InSight(Interior Exploration using Seismic Investigations,Geodesy,and Heat Transport)mission has recorded continuous ambient noise signals with many spectral peaks since its landing in *** majority of these peaks are modes produced by instrumental vibrations and are associated with environmental factors,such as temperature and wind energy *** how these modes react under various conditions is crucial because it aids in identifying their *** this study,we analyzed the three-component spectra of InSight recordings from sols 184–738 and obtained the horizontal-to-vertical spectral ratio(HVSR,also known as H/V)curves for different time *** primary modes,such as those at 3.3 and 4.1 Hz,exhibited different behaviors,suggesting diverse *** modes were sensitive to low temperature and some were sensitive to high ***,we investigated the influence of wind and temperature on the H/V *** peak frequency was mainly affected by temperature,whereas the H/V value was not associated with the temperature or wind *** these modes and elucidating their origins are significant for processing signals from InSight and can provide valuable guidance for designing future planetary seismometers.

关键词： Mars InSight spectral peaks H/V curve

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Long-lived lunar volcanism sustained by precession-driven core-mantle friction

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National Science Review 2024年第2期11卷 114-123页

作者： Shuoran Yu Xiao Xiao Shengxia Gong Nicola Tosi Jun Huang Doris Breuer Long Xiao Dongdong Ni State Key Laboratory of Lunar and Planetary Sciences Macau University of Science and Technology Planetary Science Institute State Key Laboratory of Geological Processes and Mineral Resources School of Earth Sciences China University of Geosciences CAS Key Laboratory of Planetary Sciences Shanghai Astronomical Observatory Institute of Planetary Research German Aerospace Centre(DLR)

Core-mantle friction induced by the precession of the Moon's spin axis is a strong heat source in the deep lunar mantle during the early phase of a satellite's evolution, but its influence on the long-term thermal evolution still remains poorly explored. Using a one-dimensional thermal evolution model, we show that core-mantle friction can sustain global-scale partial melting in the upper lunar mantle until ～3.1 Ga, thus accounting for the intense volcanic activity on the Moon before ～3.0 Ga. Besides, core-mantle friction tends to suppress the secular cooling of the lunar core and is unlikely to be an energy source for the long-lived lunar core dynamo. Our model also favours the transition of the Cassini state before the end of the lunar magma ocean phase(～4.2 Ga), which implies a decreasing lunar obliquity over time after the solidification of the lunar magma ocean. Such a trend of lunar obliquity evolution may allow volcanically released water to be buried in the lunar regolith of the polar regions. As a consequence, local water ice could be more abundant than previously thought when considering only its accumulation caused by solar wind and comet spreading.

关键词： Moon precession orbit volcanism

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Assessing the effects of model parameter assumptions on surface-wave inversion results

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earthquake Science 2024年第6期37卷 529-545页

作者： Xuezhen Zhang Xiaodong Song SinoProbe Laboratory School of Earth and Space SciencesPeking UniversityBeijing 100871China Hebei Hongshan National observatory on Thick Sediments and Seismic Hazards Beijing 100871China

Surface-wave inversion is a powerful tool for revealing the earth's internal ***,aside from shear-wave velocity(v_(S)),other parameters can influence the inversion outcomes,yet these have not been systematically *** study investigates the influence of various parameter assumptions on the results of surface-wave inversion,including the compressional and shear velocity ratio(v_(P)/v_(S)),shear-wave attenuation(Q_(S)),density(ρ),Moho interface,and sedimentary *** constructed synthetic models to generate dispersion data and compared the obtained results with different parameter assumptions with those of the true *** results indicate that the v_(P)/v_(S) ratio,Q_(S),and density(ρ) have minimal effects on absolute velocity values and perturbation patterns in the ***,assumptions about the Moho interface and sedimentary layer significantly influenced absolute velocity values and perturbation *** an erroneous Mohointerface depth in the initial model of the inversion significantly affected the v_(S) model near that depth,while using a smooth initial model results in relatively minor *** assumption on the sedimentary layer not only affects shallow structure results but also impacts the result at greater ***-linear inversion methods outperform linear inversion methods,particularly for the assumptions of the Moho interface and sedimentary *** inversion with other data types,such as receiver functions or Rayleigh wave ellipticity,and using data from a broader period range or higher-mode surface waves,can mitigate these ***,incorporating more accurate prior information can improve inversion results.

关键词： shear-wave velocity model surface-wave inversion Moho interface sedimentary layer non-linear inversion

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Cascading multi-segment rupture process of the 2023 Turkish earthquake doublet on a complex fault system revealed by teleseismic P wave back projection method

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earthquake Science 2024年第2期37卷 158-173页

作者： Bonan Cao Zengxi Ge Department of Geophysics School of Earth and Space SciencesPeking UniversityBeijing 100871China Hebei Hongshan National Geophysical observatory for Thick Sediments and Seismic Hazards Peking UniversityBeijing 100871China

In this study,the vertical components of broadband teleseismic P wave data recorded by China earthquake Network are used to image the rupture processes of the February 6th,2023 Turkish earthquake doublet via back projection *** in two frequency bands(0.5-2 Hz and 1-3 Hz)are used in the imaging *** results show that the rupture of the first event extends about 200 km to the northeast and about 150 km to the southwest,lasting~90 s in *** southwestern rupture is triggered by the northeastern rupture,demonstrating a sequential bidirectional unilateral rupture *** rupture of the second event extends approximately 80 km in both northeast and west directions,lasting~35 s in total and demonstrates a typical bilateral rupture *** cascading ruptures on both sides also reflect the occurrence of selective rupture behaviors on bifurcated *** addition,we observe super-shear ruptures on certain fault sections with relatively straight fault structures and sparse aftershocks.

关键词： 2023 Turkish earthquake doublet back projection method cascading segmented rupture process coseismic triggering super-shear ruptures

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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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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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3D near-surface P-wave velocity structure imaging with Distributed Acoustic Sensing and electric hammer source

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earthquake Research Advances 2024年第3期4卷 27-33页

作者： Heting Hong Fu Yin Yuhang Lei Yulan Li Baoshan Wang Deep Space Exploration Laboratory University of Science and Technology of ChinaHefei230026China School of earth and Space Sciences University of Science and Technology of ChinaHefei230026China Mengcheng National Geophysical observatory University of Science and Technology of ChinaHefei230026China

Distributed Acoustic Sensing(DAS) is an emerging technique for ultra-dense seismic observation, which provides a new method for high-resolution sub-surface seismic imaging. Recently a large number of linear DAS arrays have been used for two-dimensional S-wave near-surface imaging in urban areas. In order to explore the feasibility of three-dimensional(3D) structure imaging using a DAS array, we carried out an active source experiment at the Beijing National earth observatory. We deployed a 1 km optical cable in a rectangular shape, and the optical cable was recast into 250 sensors with a channel spacing of 4 m. The DAS array clearly recorded the P, S and surface waves generated by a hammer source. The first-arrival P wave travel times were first picked with a ShortTerm Average/Long-Term Average(STA/LTA) method and further manually checked. The P-wave signals recorded by the DAS are consistent with those recorded by the horizontal components of short-period seismometers. At shorter source-receiver distances, the picked P-wave arrivals from the DAS recording are consistent with vertical component recordings of seismometers, but they clearly lag behind the latter at greater *** is likely due to a combination of the signal-to-noise ratio and the polarization of the incoming wave. Then,we used the Tomo DD software to invert the 3D P-wave velocity structure for the uppermost 50 m with a resolution of 10 m. The inverted P-wave velocity structures agree well with the S-wave velocity structure previously obtained through ambient noise tomography. Our study indicates the feasibility of 3D near-surface imaging with the active source and DAS array. However, the inverted absolute velocity values at large depths may be biased due to potential time shifts between the DAS recording and seismometer at large source-receiver distances.

关键词： Distributed Acoustic Sensing(DAS) Near-surface structure First-arrival travel time tomography Body wave Active source

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