Next Generation Computers Warrant Next Generation Groundwater Models

Modern hydrologic models have extraordinary capabilities for representing complex process in surface-subsurface systems. These capabilities have revolutionized the way we conceptualize flow systems, but how to represent uncertainty in simulated flow systems is not as well developed. Currently, characterizing model uncertainty can be computationally expensive, in part, because the techniques are appended to the numerical methods rather than seamlessly integrated. The next generation of computers, however, presents opportunities to reformulate the modeling problem so that the uncertainty components are handled more directly within the flow system simulation. Misconceptions about quantum computing abound and they will not be a “silver bullet” for solving all complex problems, but they might be leveraged for certain kinds of highly uncertain problems, such as groundwater (GW). The point of this issue paper is that the GW community could try to revise the foundations of our models so that the governing equations being solved are tailored specifically for quantum computers. The goal moving forward should not just be to accelerate the models we have, but also to address their deficiencies. Embedding uncertainty into the models by evolving distribution functions will make predictive GW modeling more complicated, but doing so places the problem into a complexity class that is highly efficient on quantum computing hardware. Next generation GW models could put uncertainty into the problem at the very beginning of a simulation and leave it there throughout, providing a completely new way of simulating subsurface flows.     

NGA计划简介

NGA（Next Generation Attenuation）是一个合作研究计划,由太平洋地震工程研究中心生命线计划（PEER-LL）、美国地质调查所（USGS）、南加州研究中心（SECE）联合实施。该计划旨在通过一个广泛而高度协作的研究计划,研发全新的地震动衰减关系。在整个研发计划中,5套衰减关系由5个互相独立而又互相协作的团队同时研发。该计划的参与者几乎包括了该领域所有美国的顶级专家。希望本文能给我国地震动衰减关系及地震动区划的研究者带来一些启示。     

关于下一代地震区划图编制原则与关键技术的初步探讨

本文在回顾我国四代地震区划编图原则的基础上,结合对未来我国社会经济发展状况和国家地震安全政策变化的分析,同时对国际上地震区划研究进展与编图工作的现状了解,探讨了下一代地震区划编图的基本原则,提出了与之相关的基本科学技术问题,对第五代地震区划图的编制提出了初步的建议。     

Next Generation Gravity Missions to Address the Challenges of High-Precision Space Gravimetry

Izvestiya, Physics of the Solid Earth - Abstract—Satellite constellations consisting of two spacecraft (SC) pairs moving in different orbits—the so-called next-generation gravity...     

Next stop: the Moon

Andrew J Ball, Sarah K Dunkin and David J Heather report on optimistic and innovative ideas raised at the Fourth International Conference on Exploration and Utilisation of the Moon, which resulted in a declaration reviewing the current state of lunar exploration and setting targets for future work.     

Generation of hazard-consistent ground motion

This paper presents an integrated approach for evaluating seismic hazard and establishing ground motion at a site. In this approach, we combine the advantage of probabilistic and deterministic seismic hazard analyses and generate synthetic ground motion by considering the characteristics of seismic source, path attenuation, and local soil condition. Furthermore, uncertainties in seismic and soil parameters are taken into account. The proposed approach can be used to establish site-specific ground motion for engineering applications.     

Generation of critical stochastic earthquakes

A stochastic critical excitation is defined as that excitation with a given variance that maximizes the variance in the dynamic response of a system. A non-stationary filtered shot noise is used to develop a stochastic critical excitation model of an earthquake ground motion process, and the response statistics for a linear system are determined in both time and frequency domains. The sensitivity of response to several assumed earthquake pulse arrival rate functions is examined. Responses to recorded strong ground motion and to stochastic critical excitations with the same total energy are compared to assess the degree of conservatism in the procedure. An application of the procedure to seismic qualification of equipment is presented.     

Generation of hazard-consistent fragility curves

This paper presents an analytical method for generating fragility curves of structures. In the proposed method, seismic sources, path attenuation, local soil conditions, and nonlinear building behavior are systematically considered. The uncertainties in the earthquake-site-structure system are quantified by considering the uncertainties in the seismic, site, and structural parameters that define the system. For an illustration, the proposed method is used to generate fragility curves and a damge probability matrix for Smith Hall on the main campus of The University of Memphis, Memphis, Tennessee.     

Generation of spectrum compatible accelerograms

In this paper a new method is presented for generating earthquake accelerograms which have pre-established response spectra. The non-stationary random nature and other salient features of the accelerograms can be taken care of by the procedure developed. The method leads to a sample spectrum which lies above the given spectrum. The generation of records to suit several spectra simultaneously can also be handled by this approach. The method is detailed first. This is followed by several numerical examples.     

The Earth's Climate in the Next Hundred Thousand years (100 kyr)

One of the most striking features of the Quaternary paleoclimate records remains the so-called 100-kyr cycle which is undoubtedly linked to the future of our climate. Such a 100-kyr cycle is indeed characterised by long glacial periods followed by a short-interglacial (10–15 kyr long). As we are now in an interglacial, the Holocene, the previous one (the Eemian, which corresponds quite well to Marine Isotope Stage 5e, peaking at 125 kyr before present, BP) was assumed to be a good analogue for our present-day climate. In addition, as the Holocene is 10 kyr long, paleoclimatologists were naturally inclined to predict that we are quite close to the next ice age. Simulations using the 2-D climate model of Louvain-la-Neuve show, however, that the current interglacial will most probably last much longer than any previous ones. It is suggested here that this is related to the shape of the Earth's orbit around the Sun, which will be almost circular over the next tens of thousands of years. As this is primarily related to the 400-kyr cycle of eccentricity, the best and closest analogue for such a forcing is definitely Marine Isotopic Stage 11 (MIS-11), some 400 kyr ago, not MIS-5e. Because the CO₂ concentration in the atmosphere also plays an important role in shaping long-term climatic variations – especially its phase with respect to insolation – a detailed reconstruction of this previous interglacial from deep sea and ice records is urgently needed. Such a study is particularly important in the context of the already exceptional present-day CO₂ concentrations (unprecedented over the past million years) and, even more so, because of even larger values predicted to occur during the 21st century due to human activities.