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  • 1
    Electronic Resource
    Electronic Resource
    Are cratering and probably related geological records periodic? (1996)
    Springer
    Earth, moon and planets 72 (1996), S. 343-356 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The controversial topic of periodicity in geological records in relation to astronomical modeling is reviewed. Although impact cratering, frequency distribution of geo-magnetic reversals, and mass extinction of fauna yield periods when certain tests are applied, none of them can be regarded significant in the sense of mathematical statistics. The first two records yield periods of 30 Myr, while the faunal-extinction record yields a period of ~ 26 – 27 Myr. It seems that although catastrophes in the form of large impacts trigger mass extinctions, certain geophysical or geological conditions need be satisfied for mass extinctions to be realized. One should not expect to find an indisputable periodicity in cratering record because random impacts by asteroids are dominant. Thus, the earth-crossing cometary flux modulated by the galactic tidal force appears consistent with the weak detected periodicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00117540
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    Paper (German National Licenses)
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  • 2
    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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  • 3
    Electronic Resource
    Electronic Resource
    On the Possible Hazard on the Major Cities Caused by Asteroid Impact in the Pacific Ocean – II (1997)
    Springer
    Earth, moon and planets 76 (1997), S. 117-121 
    Details
    ISSN: 1573-0794
    Keywords: Asteroid ; tsunami ; economic loss
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Earlier, it was pointed out that asteroids with diameters close to 200 m that hit the Pacific Ocean once in 104 y create large tsunami waves which could cause serious hazards to the cities and countries lying along the periphery. Here, a more detailed investigation is carried out in relation to tsunami hazards created by earthquakes. It is shown that the energy involved in the asteroid induced tsunami wave is some 300 times greater than large tsunami waves and 100 times greater than the Chile tsunami of 1960, the largest this century. Second, if the impact should take place in the Pacific south of Japan, so that the tsunami wave enters Tokyo Bay, the damage could cost 800 billion dollars, which is 6 times greater than the damage due to the Hanshin (Kōbe-Osaka) earthquake of 1995.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006091826493
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    Paper (German National Licenses)
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  • 4
    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)
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