Elongated Crater Diameter

The seismic reflection database has revealed in detail Mjolnir's distinct radial zonation pattern of the impact-induced relief (Fig. 1 and 2) composed of a 12 km-wide complex outer zone, including a marginal fault zone and a modestly elevated peak ring, a 4-km-wide annular depression, and an uplifted central high, 8 km in diameter. Sharp boundary faults form a 100 to 150 m-high, near-circular rim wall and separate highly deformed strata within the crater from intact platform strata (Fig. 1 and 2). The most representative diameter for the near-circular Mjolnir crater periphery was found to be 40 km (Tsikalas et al. 1998b).

Fig. 3. Histogram of the crater diameter versus azimuth at 1° intervals around the entire Mjelnir periphery normalized to the 40 km average crater diameter. The normalized histogram lengths range from 0 to 1.

The well-established Mjolnir crater structure and morphology (Fig. 1) is fUrther used as the basis for detailed measurements on the crater diameter. In particular, the crater diameter is estimated at 1° intervals for a 360° circle at Mjolnir's periphery, and after normalization to the 40 km average crater diameter the residuals are plotted versus the azimuth direction. The resulting histogram (Fig. 3) reveals that there is a dominant elongation of the structure in a N-S/NNE-SSW direction, and a second, smaller, elongation trend at an ESE-WNW direction.

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