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  • cratering  (1)
  • nonlinear heat diffusion  (1)
  • 1
    Electronic Resource
    Electronic Resource
    On the efficiency of nuclear explosives in deflecting the orbits of NEOs (1996)
    Springer
    Earth, moon and planets 74 (1996), S. 183-189 
    Details
    ISSN: 1573-0794
    Keywords: Near Earth objects ; nuclear explosives ; nonlinear heat diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Heat transport at very high temperatures is governed by a nonlinear diffusion equation, and in order to estimate the efficiency of nuclear explosions near the surface of a near earth object (NEO) in the orbit deflecting, it is required to solve the non-linear diffusion equation. Here, the solution is obtained by similarity considerations. It is shown that the earlier (approximate) value of the efficiency obtained by Simonenko et al. of the fraction of absorbed energy to the total incident energy is an overestimate by 60%. Other differences are in the propagation velocity of the thermal front and in the time required for hydrodynamical motion to start. A brief comparison is also made with the explosion where neutrons are the major products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00055185
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A Statistical Test of Correlations and Periodicities in the Geological Records (1997)
    Springer
    Celestial mechanics and dynamical astronomy 69 (1997), S. 31-48 
    Details
    ISSN: 1572-9478
    Keywords: cratering ; mass extinction ; periodicities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Matsumoto & Kubotani argued that there is a positive and statistically significant correlation between cratering and mass extinction. This argument is critically examined by adopting a method of Ertel used by Matsumoto & Kubotani but by applying it more directly to the extinction and cratering records. It is shown that on the null-hypothesis of random distribution of crater ages, the observed correlation has a probability of occurrence of 13%. However, when large craters are excluded whose ages agree with the times of peaks of extinction rate of marine fauna, one obtains a negative correlation. This result strongly indicates that mass extinction are not due to accumulation of impacts but due to isolated gigantic impacts. Further, correlations between cratering and flood basalts and between mass extinction and flood basalts originally recognized by Stothers are further investigated. It is shown that for the former, large craters corresponds to 7 of 11 major flood basalts. Periodicity analyses are carried out for the geomagnetic reversal events and extinction rate peaks recently given by Sepkoski for the interval up to 540 M yr BP. The former exhibits a significant periodicity at P = 15 M yr, but the latter shows no significant period. It seems premature to regard the periodicity in geological records established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008313929503
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    Paper (German National Licenses)
    Fulltext
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