Path and site effects deduced from transfrontier internet macroseismic data of two recent M4 earthquakes in NW Europe

Abstract. The online collection of earthquake testimonies in Europe is strongly fragmented across numerous seismological agencies. This paper demonstrates how collecting and merging “Did You Feel It?” (DYFI) institutional macroseismic data strongly improves the quality of real-time intensity maps. Instead of using ZIP code Community Internet Intensity Maps we geocode individual response addresses for location improvement, assign intensities to grouped answers within 100 km2 grid cells, and generate intensity attenuation relations from the grid cell intensities. Grid cell intensity maps are less subjective and illustrate a more homogeneous intensity distribution than the ZIP code intensity maps. Using grid cells for ground motion analysis offers an advanced method for exchanging transfrontier equal-area intensity data without sharing any personal’s information. The applicability of the method is demonstrated on the DYFI responses of two well-felt earthquakes: the 8 September 2011 ML 4.3 (MW 3.7) Goch (Germany) and the 22 May 2015 ML 4.2 (MW 3.7) Ramsgate (UK) earthquakes. Both events resulted in non-circular distribution of intensities which is not explained by geometrical amplitude attenuation alone but illustrates an important low-pass filtering due the sedimentary cover above the Anglo-Brabant Massif and in the Lower Rhine Graben. Our study illustrates the effect of increasing bedrock depth on intensity attenuation and the importance of the WNW-ESE Caledonian structural axis of the Anglo-Brabant Massif on seismic wave propagation: seismic waves are less attenuated – high Q – along the strike of the massif but are stronger attenuated – low Q – perpendicular to this structure, especially when they cross rheologically different seismotectonic units that are separated by crustal-rooted faults.

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Path and site effects deduced from merged transfrontier internet macroseismic data of two recent <i>M</i>4 earthquakes in northwest Europe using a grid cell approach

Solid Earth ◽

10.5194/se-8-453-2017 ◽

2017 ◽

Vol 8 (2) ◽

pp. 453-477 ◽

Cited By ~ 7

Author(s):

Koen Van Noten ◽

Thomas Lecocq ◽

Christophe Sira ◽

Klaus-G. Hinzen ◽

Thierry Camelbeeck

Keyword(s):

Personal Information ◽

Sedimentary Cover ◽

Grid Cell ◽

Individual Response ◽

Macroseismic Data ◽

Grid Cells ◽

Attenuation Relations ◽

Circular Distribution ◽

Intensity Attenuation ◽

Zip Code

Abstract. The online collection of earthquake reports in Europe is strongly fragmented across numerous seismological agencies. This paper demonstrates how collecting and merging online institutional macroseismic data strongly improves the density of observations and the quality of intensity shaking maps. Instead of using ZIP code Community Internet Intensity Maps, we geocode individual response addresses for location improvement, assign intensities to grouped answers within 100 km2 grid cells, and generate intensity attenuation relations from the grid cell intensities. Grid cell intensity maps are less subjective and illustrate a more homogeneous intensity distribution than communal ZIP code intensity maps. Using grid cells for ground motion analysis offers an advanced method for exchanging transfrontier equal-area intensity data without sharing any personal information. The applicability of the method is demonstrated on the felt responses of two clearly felt earthquakes: the 8 September 2011 ML 4.3 (Mw 3.7) Goch (Germany) and the 22 May 2015 ML 4.2 (Mw 3.7) Ramsgate (UK) earthquakes. Both events resulted in a non-circular distribution of intensities which is not explained by geometrical amplitude attenuation alone but illustrates an important low-pass filtering due to the sedimentary cover above the Anglo-Brabant Massif and in the Lower Rhine Graben. Our study illustrates the effect of increasing bedrock depth on intensity attenuation and the importance of the WNW–ESE Caledonian structural axis of the Anglo-Brabant Massif for seismic wave propagation. Seismic waves are less attenuated – high Q – along the strike of a tectonic structure but are more strongly attenuated – low Q – perpendicular to this structure, particularly when they cross rheologically different seismotectonic units separated by crustal-rooted faults.

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Description and Analysis of a 20-Year (1960-79) Digital Ice-Concentration Database for the Great Lakes of North America

Annals of Glaciology ◽

10.1017/s0260305500005164 ◽

1983 ◽

Vol 4 ◽

pp. 14-18 ◽

Cited By ~ 2

Author(s):

Raymond A. Assel

Keyword(s):

North America ◽

Great Lakes ◽

Surface Area ◽

Information Service ◽

Grid Cell ◽

Ice Cover ◽

Unit Surface Area ◽

Grid Cells ◽

Data Set ◽

Ice Concentration

A digital ice-concentration database spanning 20 years (1960 to 1979) was established for the Great Lakes of North America. Data on ice concentration, i.e. the percentage of a unit surface area of the lake that is ice-covered, were abstracted from over 2 800 historic ice charts produced by United States and Canadian government agencies. The database consists of ice concentrations ranging from zero to 100% in 10% increments for individual grid cells of size 5 × 5 km constituting the surface area of each Great Lake. The data set for each of the Great Lakes was divided into half-month periods for statistical analysis. Maxinium, minimum, median, mode, and average ice-concentrations statistics were calculated for each grid cell and half-month period. A lakewide average value was then calculated for each of the half-month ice-concentration statistics for all grid cells for a given lake. Ice-cover variability and the normal extent and progression of the ice cover is discussed within the context of the lakewide averaged value of the minimum and maximum ice concentrations and the lakewide averaged value of the median ice concentrations, respectively. Differences in ice-cover variability among the five Great Lakes are related to mean lake depth and accumulated freezing degree-days. A Great Lakes ice atlas presenting a series of ice charts which depict the maximum, minimum, and median icecover concentrations for each of the Great Lakes for nine half-monthly periods, starting the last half of December and continuing through the last half of April will be published in 1983 by the National Oceanic and Atmospheric Administration (NOAA). The database will be archived at the National Snow and Ice Data Center of the National Environmental Satellite Data and Information Service (NESDIS) in Boulder, Colorado, USA, also in 1983.

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A new discrete multiplicative random cascade model for downscaling intermittent rainfall fields

10.5194/hess-2019-449 ◽

2019 ◽

Author(s):

Marc Schleiss

Keyword(s):

Classical Method ◽

Mathematical Problem ◽

Grid Cell ◽

Cascade Model ◽

Small Scale ◽

Grid Cells ◽

Cascade Generator ◽

Cascade Models ◽

First Results ◽

Original Amount

Abstract. Spatial downscaling of rainfall fields is a challenging mathematical problem for which many different types of methods have been proposed. One popular solution consists in redistributing rainfall amounts over smaller and smaller scales by means of a discrete multiplicative random cascade (DMRC). This works well for slowly varying, homogeneous rainfall fields but often fails in the presence of intermittency (i.e., large amounts of zero rainfall values). The most common workaround in this case is to use two separate cascade models, one for the occurrence and another for the intensity. In this paper, a new and simpler approach based on the notion of equal-volume areas (EVAs) is proposed. Unlike classical cascades where rainfall amounts are redistributed over grid cells of equal size, the EVA cascade splits grid cells into areas of different sizes, each of them containing exactly half of the original amount of water. The relative areas of the sub-grid cells are determined by drawing random values from a logit-normal cascade generator model with scale and intensity dependent standard deviation. The process ends when the amount of water in each sub-grid cell is smaller than a fixed bucket capacity, at which point the output of the cascade can be re-sampled over a regular Cartesian mesh. The present paper describes the implementation of the EVA cascade model and gives some first results for 100 selected events in the Netherlands. Performance is assessed by comparing the outputs of the EVA model to bilinear interpolation and to a classical DMRC model based on fixed grid cell sizes. Results show that on average, the EVA cascade outperforms the classical method, producing fields with more realistic distributions, small-scale extremes and spatial structures. Improvements are mostly credited to the higher robustness of the EVA model to the presence of intermittency and to the lower variance of its generator. However, improvements are not systematic and both approaches have their advantages and weaknesses. For example, while the classical cascade tends to overestimate small-scale extremes and variability, the EVA model tends to produce fields that are slightly too smooth and blocky compared with observations.

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Neurobiological successor features for spatial navigation

10.1101/789412 ◽

2019 ◽

Cited By ~ 3

Author(s):

William de Cothi ◽

Caswell Barry

Keyword(s):

Grid Cell ◽

Biological Data ◽

Basis Set ◽

Grid Cells ◽

Dimensional Representation ◽

Boundary Vector ◽

Good Account ◽

Cell Firing ◽

Low Dimensional ◽

Environmental Geometry

AbstractThe hippocampus has long been observed to encode a representation of an animal’s position in space. Recent evidence suggests that the nature of this representation is somewhat predictive and can be modelled by learning a successor representation (SR) between distinct positions in an environment. However, this discretisation of space is subjective making it difficult to formulate predictions about how some environmental manipulations should impact the hippocampal representation. Here we present a model of place and grid cell firing as a consequence of learning a SR from a basis set of known neurobiological features – boundary vector cells (BVCs). The model describes place cell firing as the successor features of the SR, with grid cells forming a low-dimensional representation of these successor features. We show that the place and grid cells generated using the BVC-SR model provide a good account of biological data for a variety of environmental manipulations, including dimensional stretches, barrier insertions, and the influence of environmental geometry on the hippocampal representation of space.

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Path integration in place cells of developing rats

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1719054115 ◽

2018 ◽

Vol 115 (7) ◽

pp. E1637-E1646 ◽

Cited By ~ 18

Author(s):

Tale L. Bjerknes ◽

Nenitha C. Dagslott ◽

Edvard I. Moser ◽

May-Britt Moser

Keyword(s):

Path Integration ◽

Grid Cell ◽

Cell System ◽

Place Cells ◽

Postnatal Life ◽

Motion Information ◽

Grid Cells ◽

Adult Rats ◽

Self Motion ◽

Made In

Place cells in the hippocampus and grid cells in the medial entorhinal cortex rely on self-motion information and path integration for spatially confined firing. Place cells can be observed in young rats as soon as they leave their nest at around 2.5 wk of postnatal life. In contrast, the regularly spaced firing of grid cells develops only after weaning, during the fourth week. In the present study, we sought to determine whether place cells are able to integrate self-motion information before maturation of the grid-cell system. Place cells were recorded on a 200-cm linear track while preweaning, postweaning, and adult rats ran on successive trials from a start wall to a box at the end of a linear track. The position of the start wall was altered in the middle of the trial sequence. When recordings were made in complete darkness, place cells maintained fields at a fixed distance from the start wall regardless of the age of the animal. When lights were on, place fields were determined primarily by external landmarks, except at the very beginning of the track. This shift was observed in both young and adult animals. The results suggest that preweaning rats are able to calculate distances based on information from self-motion before the grid-cell system has matured to its full extent.

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Grid Cells Lose Coherence in Realistic Environments

10.5772/intechopen.100310 ◽

2021 ◽

Author(s):

Yifan Luo ◽

Matteo Toso ◽

Bailu Si ◽

Federico Stella ◽

Alessandro Treves

Keyword(s):

Short Range ◽

Short Range Order ◽

Grid Cell ◽

Place Cells ◽

Grid Cells ◽

Lateral Connectivity ◽

Cell Pattern ◽

In The Wild ◽

Freely Moving ◽

Adaptation Model

Spatial cognition in naturalistic environments, for freely moving animals, may pose quite different constraints from that studied in artificial laboratory settings. Hippocampal place cells indeed look quite different, but almost nothing is known about entorhinal cortex grid cells, in the wild. Simulating our self-organizing adaptation model of grid cell pattern formation, we consider a virtual rat randomly exploring a virtual burrow, with feedforward connectivity from place to grid units and recurrent connectivity between grid units. The virtual burrow was based on those observed by John B. Calhoun, including several chambers and tunnels. Our results indicate that lateral connectivity between grid units may enhance their “gridness” within a limited strength range, but the overall effect of the irregular geometry is to disable long-range and obstruct short-range order. What appears as a smooth continuous attractor in a flat box, kept rigid by recurrent connections, turns into an incoherent motley of unit clusters, flexible or outright unstable.

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Proposal for delineation of Botanical regions in Australia.

Brunonia ◽

10.1071/bru9840195 ◽

1984 ◽

Vol 7 (1) ◽

pp. 195 ◽

Cited By ~ 3

Author(s):

BA Barlow

Keyword(s):

Data Base ◽

Grid Cell ◽

Grid Cells ◽

Cell Mapping ◽

Geographic Distributions ◽

Mapping Systems

A division of Australia into 33 botanical regions is proposed. The regions may be useful for describing and illustrating geographic distributions of plant taxa, for arrangement of specimens in herbaria, or for data base construction. The proposed common boundaries of the botanical regions are meridians of longitude and parallels of latitude, generating regions comprising from 10 to 44 1-degree grid cells. The botanical regions proposed are thus compatible with grid cell mapping systems.

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Network mechanisms of grid cells

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2012.0511 ◽

2014 ◽

Vol 369 (1635) ◽

pp. 20120511 ◽

Cited By ~ 37

Author(s):

Edvard I. Moser ◽

May-Britt Moser ◽

Yasser Roudi

Keyword(s):

Functional Organization ◽

Cell Formation ◽

Grid Cell ◽

Mammalian Brain ◽

Grid Cells ◽

Entire Space ◽

Competitive Network ◽

Sensory Cortices ◽

Firing Properties ◽

Organizing Principles

One of the major breakthroughs in neuroscience is the emerging understanding of how signals from the external environment are extracted and represented in the primary sensory cortices of the mammalian brain. The operational principles of the rest of the cortex, however, have essentially remained in the dark. The discovery of grid cells, and their functional organization, opens the door to some of the first insights into the workings of the association cortices, at a stage of neural processing where firing properties are shaped not primarily by the nature of incoming sensory signals but rather by internal self-organizing principles. Grid cells are place-modulated neurons whose firing locations define a periodic triangular array overlaid on the entire space available to a moving animal. The unclouded firing pattern of these cells is rare within the association cortices. In this paper, we shall review recent advances in our understanding of the mechanisms of grid-cell formation which suggest that the pattern originates by competitive network interactions, and we shall relate these ideas to new insights regarding the organization of grid cells into functionally segregated modules.

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A Budyko framework for estimating how spatial heterogeneity and lateral moisture redistribution affect average evapotranspiration rates as seen from the atmosphere

Hydrology and Earth System Sciences ◽

10.5194/hess-21-217-2017 ◽

2017 ◽

Vol 21 (1) ◽

pp. 217-233 ◽

Cited By ~ 19

Author(s):

Elham Rouholahnejad Freund ◽

James W. Kirchner

Keyword(s):

Spatial Heterogeneity ◽

Land Surface ◽

Potential Evapotranspiration ◽

Aridity Index ◽

Grid Cell ◽

Earth System ◽

Grid Cells ◽

Closure Relation ◽

System Models ◽

Earth System Models

Abstract. Most Earth system models are based on grid-averaged soil columns that do not communicate with one another, and that average over considerable sub-grid heterogeneity in land surface properties, precipitation (P), and potential evapotranspiration (PET). These models also typically ignore topographically driven lateral redistribution of water (either as groundwater or surface flows), both within and between model grid cells. Here, we present a first attempt to quantify the effects of spatial heterogeneity and lateral redistribution on grid-cell-averaged evapotranspiration (ET) as seen from the atmosphere over heterogeneous landscapes. Our approach uses Budyko curves, as a simple model of ET as a function of atmospheric forcing by P and PET. From these Budyko curves, we derive a simple sub-grid closure relation that quantifies how spatial heterogeneity affects average ET as seen from the atmosphere. We show that averaging over sub-grid heterogeneity in P and PET, as typical Earth system models do, leads to overestimations of average ET. For a sample high-relief grid cell in the Himalayas, this overestimation bias is shown to be roughly 12 %; for adjacent lower-relief grid cells, it is substantially smaller. We use a similar approach to derive sub-grid closure relations that quantify how lateral redistribution of water could alter average ET as seen from the atmosphere. We derive expressions for the maximum possible effect of lateral redistribution on average ET, and the amount of lateral redistribution required to achieve this effect, using only estimates of P and PET in possible source and recipient locations as inputs. We show that where the aridity index P/PET increases with altitude, gravitationally driven lateral redistribution will increase average ET (and models that overlook lateral redistribution will underestimate average ET). Conversely, where the aridity index P/PET decreases with altitude, gravitationally driven lateral redistribution will decrease average ET. The effects of both sub-grid heterogeneity and lateral redistribution will be most pronounced where P is inversely correlated with PET across the landscape. Our analysis provides first-order estimates of the magnitudes of these sub-grid effects, as a guide for more detailed modeling and analysis.

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A plume-in-grid approach to characterize air quality impacts of aircraft emissions at the Hartsfield–Jackson Atlanta International Airport

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-9285-2013 ◽

2013 ◽

Vol 13 (18) ◽

pp. 9285-9302 ◽

Cited By ~ 18

Author(s):

J. Rissman ◽

S. Arunachalam ◽

M. Woody ◽

J. J. West ◽

T. BenDor ◽

...

Keyword(s):

Air Quality ◽

Grid Cell ◽

Ground Level ◽

Grid Cells ◽

Aircraft Emissions ◽

International Airport ◽

Grid Approach ◽

Subgrid Scales ◽

Order Of Magnitude ◽

The One

Abstract. This study examined the impacts of aircraft emissions during the landing and takeoff cycle on PM2.5 concentrations during the months of June and July 2002 at the Hartsfield–Jackson Atlanta International Airport. Primary and secondary pollutants were modeled using the Advanced Modeling System for Transport, Emissions, Reactions, and Deposition of Atmospheric Matter (AMSTERDAM). AMSTERDAM is a modified version of the Community Multiscale Air Quality (CMAQ) model that incorporates a plume-in-grid process to simulate emissions sources of interest at a finer scale than can be achieved using CMAQ's model grid. Three fundamental issues were investigated: the effects of aircraft on PM2.5 concentrations throughout northern Georgia, the differences resulting from use of AMSTERDAM's plume-in-grid process rather than a traditional CMAQ simulation, and the concentrations observed in aircraft plumes at subgrid scales. Comparison of model results with an air quality monitor located in the vicinity of the airport found that normalized mean bias ranges from −77.5% to 6.2% and normalized mean error ranges from 40.4% to 77.5%, varying by species. Aircraft influence average PM2.5 concentrations by up to 0.232 μg m−3 near the airport and by 0.001–0.007 μg m−3 throughout the Atlanta metro area. The plume-in-grid process increases concentrations of secondary PM pollutants by 0.005–0.020 μg m−3 (compared to the traditional grid-based treatment) but reduces the concentration of non-reactive primary PM pollutants by up to 0.010 μg m−3, with changes concentrated near the airport. Examination of subgrid-scale results indicates that median aircraft contribution to grid cells is higher than median puff concentration in the airport's grid cell and outside of a 20 km × 20 km square area centered on the airport, while in a 12 km × 12 km square ring centered on the airport, puffs have median concentrations over an order of magnitude higher than aircraft contribution to the grid cells. Maximum puff impacts are seen within the 12 km × 12 km ring, not in the airport's own grid cell, while maximum grid cell impacts occur within the airport's grid cell. Twenty-one (21)% of all aircraft-related puffs from the Atlanta airport have at least 0.1 μg m−3 PM2.5 concentrations. Near the airport, median daily puff concentrations vary between 0.017 and 0.134 μg m−3 (0.05 and 0.35 μg m−3 at ground level), while maximum daily puff concentrations vary between 6.1 and 42.1 μg m−3 (7.5 and 42.1 μg m−3 at ground level) during the 2-month period. In contrast, median daily aircraft contribution to grid concentrations varies between 0.015 and 0.091 μg m−3 (0.09 and 0.40 μg m−3 at ground level), while the maximum varies between 0.75 and 2.55 μg m−3 (0.75 and 2.0 μg m−3 at ground level). Future researchers may consider using a plume-in-grid process, such as the one used here, to understand the impacts of aircraft emissions at other airports, for proposed future airports, for airport expansion projects under various future scenarios, and for other national-scale studies specifically when the maximum impacts at fine scales are of interest.

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