A spatial distribution in statistics is the arrangement of a phenomenon across the Earth's surface and a graphical display of such an arrangement is an important tool in geographical and environmental statistics.[1] A graphical display of a spatial distribution may summarize raw data directly or may reflect the outcome of a more sophisticated data analysis. Many different aspects of a phenomenon can be shown in a single graphical display by using a suitable choice of different colours to represent differences.
One example of such a display could be observations made to describe the geographic patterns of features, both physical and human across the earth.
The information included could be where units of something are, how many units of the thing there are per units of area, and how sparsely or densely packed they are from each other.
Patterns of spatial distribution
Usually, for a phenomenon that changes in space, there is a pattern that determines the location of the subject of the phenomenon and its intensity or size, in X and Y coordinates. The scientific challenge is trying to identify the variables that affect this pattern. The issue can be demonstrated with several simple examples:
The spatial distribution of the human population
The spatial distribution of the population and development are closely related to each other, especially in the context of sustainability. The challenges related to the spatial spread of a population include: rapid urbanization and population concentration, rural population, urban management and poverty housing, displaced persons and refugees. Migration is a basic element in the spatial distribution of a population, and it may remain a key driver in the coming decades, especially as an element of urbanization in developing countries.[2]
The curve above expresses the slope of the seismic intensity as a function of the distance from the epicenter, R =0.26 . When in a certain methodology the influence of the geological structure variable of each observation was neutralized, the R increases to 0.41, which means that the distance together with the geological structure already affect 41% of the variation in the spatial distribution of the intensities, and so on, one can continue and try to understand the effect of the other variables.
The spatial distribution of economic activity in the world
In a pair of studies from Brown University by urban economist J. Vernon Henderson, with co-authors Adam Storeygard and David Weil, the spatial distribution of the economic activity in the world was examined by mapping the artificial lights at night from space over 250,000 grid cells, the average area of each of which is 560 square kilometers. They found that 50% of the variation in this activity can be explained through a system of physical geographic features.[3][4]
The spatial distribution of the seismic intensities of an earthquake
The seismic intensityies of an earthquake are distributed across space with an elementary regularity, so that in towns located close to the epicenter of the earthquake, high seismic intensities are observed and vice versa; Low intensities were observed in settlements far from the epicenter. The distance of each settlement from the epicenter is marked with XY coordinates, a variable that affects the seismic intensity observed there. But there are other variables that affect these intensities, such as the geological structure of each settlement, its topography, and more. All these make the simple regularity of the effect of the distance variable more complex. If we succeed in identifying the contribution of most of the variables to the fact that Intensity Z occurred in the XY settlement and not other one, we will understand the pattern that stands behind the organization of the seismic intensity in a specific earthquake, a fact that will help us in the field of seismic risks surveys and their assessments.[5]
The spatial distribution of a population with health impairments related to vitamin A deficiency
Vitamin A deficiency is a major public health problem in poor societies. Dietary consumption of foods rich with vitamin A was low in Ethiopia. In 2021, a study was published that evaluated the spatial distribution and the spatial variables affecting it in dietary consumption of foods rich (or poor) in vitamin A among children aged 6–23 months in Ethiopia.[6]
More examples
Many police departments colour-code a city map based on crime statistics.
The two-step floating catchment area (2SFCA) method has been used to prepare maps showing the relative accessibility of individuals (demand units) to physicians (supply units), by shading which shows many different degrees of accessibility.
↑ Avni, R., 1999. The 1927 Jericho Earthquake: Comprehensive Macroseismic Analysis Based on Contemporary Sources. Ben-Gurion University of the Negev, pp. 35-38D.
An earthquake – also called a quake, tremor, or temblor – is the shaking of the surface of Earth resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those that are so weak that they cannot be felt, to those violent enough to propel objects and people into the air, damage critical infrastructure, and wreak destruction across entire cities. The seismic activity of an area is the frequency, type, and size of earthquakes experienced over a particular time. The seismicity at a particular location in the Earth is the average rate of seismic energy release per unit volume. The word tremor is also used for non-earthquake seismic rumbling.
In physics, attenuation is the gradual loss of flux intensity through a medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at variable attenuation rates.
Economic geography is the subfield of human geography that studies economic activity and factors affecting it. It can also be considered a subfield or method in economics. There are four branches of economic geography.
The 1811–1812 New Madrid earthquakes were a series of intense intraplate earthquakes beginning with an initial earthquake of moment magnitude 7.2–8.2 on December 16, 1811, followed by a moment magnitude 7.4 aftershock on the same day. Two additional earthquakes of similar magnitude followed in January and February 1812. They remain the most powerful earthquakes to hit the contiguous United States east of the Rocky Mountains in recorded history. The earthquakes, as well as the seismic zone of their occurrence, were named for the Mississippi River town of New Madrid, then part of the Louisiana Territory and now within the U.S. state of Missouri.
The New Madrid Seismic Zone, sometimes called the New Madrid Fault Line, is a major seismic zone and a prolific source of intraplate earthquakes in the Southern and Midwestern United States, stretching to the southwest from New Madrid, Missouri.
A choropleth map is a type of statistical thematic map that uses pseudocolor, meaning color corresponding with an aggregate summary of a geographic characteristic within spatial enumeration units, such as population density or per-capita income.
A heat map is a 2-dimensional data visualization technique that represents the magnitude of individual values within a dataset as a color. The variation in color may be by hue or intensity.
A thematic map is a type of map that portrays the geographic pattern of a particular subject matter (theme) in a geographic area. This usually involves the use of map symbols to visualize selected properties of geographic features that are not naturally visible, such as temperature, language, or population. In this, they contrast with general reference maps, which focus on the location of a diverse set of physical features, such as rivers, roads, and buildings. Alternative names have been suggested for this class, such as special-subject or special-purpose maps, statistical maps, or distribution maps, but these have generally fallen out of common usage. Thematic mapping is closely allied with the field of Geovisualization.
GeoDa is a free software package that conducts spatial data analysis, geovisualization, spatial autocorrelation and spatial modeling.
Spatial inequality refers to the unequal distribution of income and resources across geographical regions. Attributable to local differences in infrastructure, geographical features and economies of agglomeration, such inequality remains central to public policy discussions regarding economic inequality more broadly.
The Richter scale, also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale, is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 paper, where he called it the "magnitude scale". This was later revised and renamed the local magnitude scale, denoted as ML or ML .
A dot distribution map is a type of thematic map that uses a point symbol to visualize the geographic distribution of a large number of related phenomena. Dot maps are a type of unit visualizations that rely on a visual scatter to show spatial patterns, especially variances in density. The dots may represent the actual locations of individual phenomena, or be randomly placed in aggregation districts to represent a number of individuals. Although these two procedures, and their underlying models, are very different, the general effect is the same.
The 1940 Vrancea earthquake, also known as the 1940 Bucharest earthquake, occurred on Sunday, 10 November 1940, in Romania, at 03:39, when the majority of the population was at home.
Recent advances are improving the speed and accuracy of loss estimates immediately after earthquakes so that injured people may be rescued more efficiently. "Casualties" are defined as fatalities and injured people, which are due to damage to occupied buildings. After major and large earthquakes, rescue agencies and civil defense managers rapidly need quantitative estimates of the extent of the potential disaster, at a time when information from the affected area may not yet have reached the outside world. For the injured below the rubble every minute counts. To rapidly provide estimates of the extent of an earthquake disaster is much less of a problem in industrialized than in developing countries. This article focuses on how one can estimate earthquake losses in developing countries in real time.
A geographical cluster is a localized anomaly, usually an excess of something given the distribution or variation of something else. Often it is considered as an incidence rate that is unusual in that there is more of some variable than might be expected. Examples would include: a local excess disease rate, a crime hot spot, areas of high unemployment, accident blackspots, unusually high positive residuals from a model, high concentrations of flora or fauna, areas with high levels of creative activity, physical features or events like earthquake epicenters etc...
A map symbol or cartographic symbol is a graphical device used to visually represent a real-world feature on a map, working in the same fashion as other forms of symbols. Map symbols may include point markers, lines, regions, continuous fields, or text; these can be designed visually in their shape, size, color, pattern, and other graphic variables to represent a variety of information about each phenomenon being represented.
The 1930 Senigallia earthquake struck the city of Senigallia in central Italy on October 30. It occurred just a few months after the destructive 1930 Irpinia earthquake, which had caused over 1,400 casualties in the southern part of the country.
The 2020 Kashgar earthquake, also known as the Jiashi earthquake occurred on 19 January 2020 at 21:27:56 China Standard Time in Xinjiang Province, China. According to the United States Geological Survey, the earthquake had a moment magnitude of 6.0 and a surface wave magnitude of 6.4 according to the China Earthquake Network Center. It struck at a shallow depth of 5.6 km according to the USGS while the CENC has the figure at 16 km. Local emergency management agencies said the earthquake damaged more than 1,000 homes and businesses in the nearby populated towns and villages. One person is known to have died while two other children were injured.
The 1997 Bojnurd earthquake occurred on 4 February at 14:07 IRST in Iran. The epicenter of the Mw 6.5 earthquake was in the Kopet Dag mountains of North Khorasan, near the Iran–Turkmenistan border, about 579 km (360 mi) northeast of Tehran. The earthquake is characterized by shallow strike-slip faulting in a zone of active faults. Seismic activity is present as the Kopet Dag is actively accommodating tectonics through faulting. The earthquake left 88 dead, 1,948 injured, and affected 173 villages, including four which were destroyed. Damage also occurred in Shirvan and Bojnord counties. The total cost of damage was estimated to be over US$ 30 million.
John Vernon Henderson is a Canadian-American economist and an academic. He is a Research Affiliate at the International Growth Centre, Director of the Urbanisation in Developing Countries Program, and a School Professor of Economic Geography at the London School of Economics.
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