circularity index

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1 The ratio between the area of an inscribed circle to the area of a circumscribed circle fitted to the outline of the crest of a crater (see crater 2). For fresh lunar craters, the average circularity index reaches a maximum value of about 0.85–0.90 for craters about 10 km in diameter.

2 See drainage basin shape index.

Subjects: Earth Sciences and Geography.

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