Developing a novel hybrid model for seismic loss prediction of regional-scale buildings

Bulletin of Earthquake Engineering - Seismic loss prediction of regional-scale buildings provides key information for disaster management. However, previous seismic loss prediction models ignored...     

Estimation of constant-damage residual displacements in terms of maximum inelastic displacements for SDOF structures

Bulletin of Earthquake Engineering - This paper investigates the constant-damage residual displacement ratios Cr (i.e., the ratio of the residual displacement in terms of the maximum inelastic...     

Multi-scale climate variations and mechanisms of the onset and withdrawal of the South China Sea summer monsoon

Science China Earth Sciences - The onset of the South China Sea summer monsoon (SCSSM) heralds the establishment of the large-scale East Asian summer monsoon and the western North Pacific summer...     

Under the surface: Pressure-induced planetary-scale waves,volcanic lightning,and gaseous clouds caused by the submarine eruption of Hunga Tonga-Hunga Ha'apai volcano

We present a narrative of the eruptive events culminating in the cataclysmic January 15, 2022 eruption of Hunga Tonga-Hunga Ha'apai Volcano by synthesizing diverse preliminary seismic, volcanological, sound wave, and lightning data available within the first few weeks after the eruption occurred. The first hour of eruptive activity produced fast-propagating tsunami waves, long-period seismic waves, loud audible sound waves, infrasonic waves, exceptionally intense volcanic lightning and an unsteady volcanic plume that transiently reached—at 58 ?km—the Earth's mesosphere. Energetic seismic signals were recorded worldwide and the globally stacked seismogram showed episodic seismic events within the most intense periods of phreatoplinian activity, and they correlated well with the infrasound pressure waveform recorded in Fiji. Gravity wave signals were strong enough to be observed over the entire planet in just the first few hours, with some circling the Earth multiple times subsequently. These large-amplitude, long-wavelength atmospheric disturbances come from the Earth's atmosphere being forced by the magmatic mixture of tephra, melt and gasses emitted by the unsteady but quasi-continuous eruption from 0402±1–1800 UTC on January 15, 2022. Atmospheric forcing lasted much longer than rupturing from large earthquakes recorded on modern instruments, producing a type of shock wave that originated from the interaction between compressed air and ambient (wavy) sea surface. This scenario differs from conventional ideas of earthquake slip, landslides, or caldera collapse-generated tsunami waves because of the enormous (～1000x) volumetric change due to the supercritical nature of volatiles associated with the hot, volatile-rich phreatoplinian plume. The time series of plume altitude can be translated to volumetric discharge and mass flow rate. For an eruption duration of ～12 ?h, the eruptive volume and mass are estimated at 1.9 ?km³ and ～2 900 ?Tg, respectively, corresponding to a VEI of 5–6 for this event. The high frequency and intensity of lightning was enhanced by the production of fine ash due to magma—seawater interaction with concomitant high charge per unit mass and the high pre-eruptive concentration of dissolved volatiles. Analysis of lightning flash frequencies provides a rapid metric for plume activity and eruption magnitude. Many aspects of this eruption await further investigation by multidisciplinary teams. It represents a unique opportunity for fundamental research regarding the complex, non-linear behavior of high energetic volcanic eruptions and attendant phenomena, with critical implications for hazard mitigation, volcano forecasting, and first-response efforts in future disasters.     

川东南盆缘常压区页岩裂缝脉体特征及古压力演化

为了查明川东南盆缘常压页岩气区五峰组页岩裂缝脉体记录的古温度及古压力特征,揭示常压页岩气区储层压力降低的主要影响因素和页岩气散失机理.以松坎地区五峰组黑色碳质页岩裂缝脉体内的流体包裹体为主要研究对象,通过显微镜光学观察、阴极发光测试、包裹体测温和激光拉曼分析,结合埋藏-生烃-热史模拟,对裂缝脉体中的气-液两相盐水包裹体和高密度甲烷包裹体进行了系统研究.研究表明:松坎地区五峰组裂缝中主要存在着两期脉体充填,M1裂缝脉体形成时间距今约103~86 Ma,脉体较宽、阴极发光颜色为橘红色,其内甲烷包裹体捕获压力为82.6~91.5 MPa,反映燕山中期盆缘地区页岩气藏处在超压状态;M2裂缝脉体生长于M1裂缝脉体两侧,形成时间距今约90~72 Ma,脉体较窄、阴极发光颜色为暗红色,其内甲烷包裹体捕获压力为43.6~47.3 MPa.综合分析认为,川东南盆缘松坎地区五峰组在燕山期经历了由超压至常压的转变.燕山期以来的抬升剥蚀与褶皱变形导致地层内大量页岩气沿着滑脱层发生侧向运移和散失,地层压力快速下降.燕山晚期时,盆内稳定构造区页岩气藏仍处于超压状态,而盆缘地区已降至常压.      

生物氧化锰矿物的研究进展

生物氧化锰矿物具有很强的氧化、催化及吸附能力,对表生元素地球化学循环有重要驱动作用,在环境科学领域具有重要应用价值。本文通过应用文献计量学方法对2001—2010年、2011—2020年生物氧化锰矿物国内外研究状况进行归纳分析,发现对生物氧化锰矿物的研究具有如下较为突出的特点:1)未命名的锰矿物较多;2)诱导矿化微生物物种范围扩大;3)微生物驱动锰氧化机制增多。作者提出需要在以下几方面开展进一步的研究:1)微生物驱动机制仍需更深层次完善;2)较为单一的室内实验与自然环境微生物诱导锰矿化存在较大差异;3)自然界微生物诱导形成的锰矿物与室内单一条件试验诱导合成的锰矿物在结构类型的不同。     

Time–frequency characteristics and trend feature of the ENPEMF signal before Lushan $${{\varvec{M}}}_{{\varvec{w}}}$$ M w 6.6 earthquake via DE-DDTFA method

Natural Hazards - The Earth's natural pulse electromagnetic field (ENPEMF) signal, is generally considered to be a nonlinear or nonstationary signal received from our instrument, placed on the...     

Influence Mechanism of Mine Pressure on Coal Seam Gas Emission During Mining

Geotechnical and Geological Engineering - Gas is one of the main factors causing coal mine accidents in China. Understanding the mechanism of the influence of mine pressure on coal seam gas...     

冻融循环作用下含水率对粗颗粒填料水分迁移影响的宏细观试验研究北大核心CSCD

冻融循环作用和初始含水率是影响粗颗粒填料水分迁移特征和冻胀融沉变形的两个主要因素。为明确冻融循环作用下,不同初始含水率粗颗粒填料的水分迁移特征及细观机制,采用荧光素为追踪剂,以CT细观机理观测为研究手段,开展了不同初始含水率条件下粗颗粒填料的一系列冻融循环试验,探究了温度场和冻深变化、水分迁移图像、补水量变化、最终含水率分布及CT值变化规律等。试验结果表明,冻深基本随冻融循环的次数增加不断加深,初始含水率越大,不同冻融循环作用下冻深的变化越稳定。外界补水量和液态水迁移高度与初始含水率呈负相关。CT扫描结果分析表明,经历多次冻融循环后,试样中的水分迁移导致土体孔隙结构及颗粒构造发生变化,试样的密度普遍增加,孔隙率以减小为主,进而导致土体发生相应变形。     

西沙群岛西科1井第四纪生物礁中典型暴露面的岩石学与孔隙特征

根据岩心观察、薄片鉴定和图像分析, 对西科1井第四纪发育的典型暴露面及其附近的岩石类型、成岩作用和孔隙类型进行了系统的分析.研究表明: 典型暴露面(埋深68.75~70.24 m)附近的岩石类型为骨架灰岩和泥粒灰岩, 成岩作用类型包括溶解作用、胶结作用、泥晶化作用和新生变形作用, 孔隙类型主要为粒间孔和粒间溶孔、粒内孔及粒内溶孔、生长骨架孔及其溶孔、铸模孔和晶间溶孔.碳酸盐矿物的悬垂状产状、生物体腔孔充填物的方解石化和普遍发育的溶解作用指示该深度段遭受了大气水淋滤的强烈改造.