Global Infrasonic Monitoring of Large Bolides.

Using recent infrasonic data (1995-2001) and older infrasonic data recorded by AFTAC (1960-1974), we have refined our estimates of the global influx rate (cumulative influx) of large bolides with sufficient strength to deeply penetrate the atmosphere (below {approx} 50 km). The number of bolides arriving as a function of their initial source energy has been estimated from a least-squares curve-fit of our database of 19 bolides (for a source energy > 0.053 kt) with the resulting values and an estimate of the associated statistical counting errors: 30.3{+-} 6 bolides at {ge}0.1 kt, 5.8{+-} 2 at {ge}1 kt and 0.84{+-} 0.25 at {ge}15 kt. In this work we also used these estimates to infer the recurrence interval for energy levels slightly outside the original source energy range, The Tunguska bolide of 1908 ({approx}10 Mt) is a prime example of a previously observed body of great interest. Almost regardless of how we analyze the recent data, the conclusion is that bolides with Tunguska type energy levels should reoccur on the average every 120{+-}10 years