Accession Number : ADA225104


Title :   Seismic Response to Sonic Boom-Coupled Rayleigh Waves


Descriptive Note : Final rept. 6 Nov 1989-6 May 1990,


Corporate Author : BBN SYSTEMS AND TECHNOLOGIES CORP CANOGA PARK CA


Personal Author(s) : Legg, Mark R ; Haber, Jerold M


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a225104.pdf


Report Date : 28 Jun 1990


Pagination or Media Count : 265


Abstract : Whenever sonic booms strike the ground a certain amount of energy is transferred to the ground which propagates as seismic waves. Under most conditions, the energy transfer is very inefficient, and the seismic wave energy is dissipated over a relatively short distance. If, however, a supersonic aircraft flew in a manner so that the sonic boom carpet velocity matched the propagation velocity of seismic surface waves (Rayleigh waves), the magnitude of the seismic waves would be amplified. For special soil (ground) characteristics, the energy transfer into the ground becomes more efficient. The seismic energy can propagate with little dissipation, allowing the magnitude of the ground vibrations to build up to damaging levels. If the vibration characteristics of the ground match those of a structure, the potential for structural damage may be significant. Three types of conditions are necessary for sonic boom-coupled Rayleigh waves to pose a threat. The overflown geologic (soil) profile must be characterized by a low velocity layer over a higher velocity layer. An aircraft must fly a steady maneuver for which the sonic boom carpet speed varies by no more than approximately + or - 10% over a distance of several wave lengths. The structures in the region must have natural frequencies matching those of the Rayleigh waves and the amplitude and duration of the waves must be great enough to cause damage. Numerous near-surface geologic conditions and soil profiles of the appropriate character exist near supersonic operating areas. (jhd)


Descriptors :   *SONIC BOOM , *ENERGY TRANSFER , *RAYLEIGH WAVES , *SEISMIC WAVES , PROPAGATION , VIBRATION , SURFACE WAVES , AIRCRAFT , DAMAGE , LAYERS , STRUCTURES , DISSIPATION , GEOLOGY , TIME , SURFACES , RESONANT FREQUENCY , LOW VELOCITY , SOILS , PROFILES , RESPONSE , SHORT RANGE(DISTANCE) , MANEUVERS , TRANSFER , MATCHING , SEISMOLOGY , WAVES , SUPERSONIC AIRCRAFT , STEADY STATE , GROUND LEVEL , MECHANICAL IMPEDANCE , VELOCITY , FREQUENCY


Subject Categories : Military Aircraft Operations
      Seismology


Distribution Statement : APPROVED FOR PUBLIC RELEASE