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The Earth Similarity Index ( ESI) is a proposed characterization of how similar a planetary-mass object or natural satellite is to Earth. It was designed to be a scale from zero to one, with Earth having a value of one; this is meant to simplify planet comparisons from large databases. The scale has no quantitative meaning for habitability .
The volcanic explosivity index ( VEI) is a relative measure of the explosiveness of volcanic eruptions. It was devised by Christopher G. Newhall of the United States Geological Survey and Stephen Self in 1982. Volume of products, eruption cloud height, and qualitative observations (using terms ranging from "gentle" to "mega-colossal") are used ...
The Modified Mercalli intensity scale ( MM, MMI, or MCS) measures the effects of an earthquake at a given location. This is in contrast with the seismic magnitude usually reported for an earthquake. Magnitude scales measure the inherent force or strength of an earthquake – an event occurring at greater or lesser depth.
In contrast, if the entire Earth was covered by water – a so-called ocean planet – the average temperature on the planet would rise to almost 27 °C (81 °F). In 2021, scientists reported that Earth dimmed by ~0.5% over two decades (1998–2017) as measured by earthshine using modern photometric techniques.
Map showing countries shaded by their score in the Happy Planet Index (2019). The Happy Planet Index ( HPI) is an index of human well-being and environmental impact that was introduced by the New Economics Foundation in 2006. Each country's HPI value is a function of its average subjective life satisfaction, life expectancy at birth, and ...
The index score can also be interpreted as the percentage of one of the two groups included in the calculation that would have to move to different geographic areas in order to produce a distribution that matches that of the larger area. The index of dissimilarity can be used as a measure of segregation. A score of zero (0%) reflects a fully ...
In seismology, the Gutenberg–Richter law [1] ( GR law) expresses the relationship between the magnitude and total number of earthquakes in any given region and time period of at least that magnitude. or. where. is the number of events having a magnitude , and are constants, i.e. they are the same for all values of and .
The normalized difference vegetation index ( NDVI) is a widely-used metric for quantifying the health and density of vegetation using sensor data. It is calculated from spectrometric data at two specific bands: red and near-infrared. The spectrometric data is usually sourced from remote sensors, such as satellites.