Hi Michael,
a month ago I localised bolide trajectory acording seismic data. It was shown that many moteoroids produce air shock waves and VLF signals too. Small bolide Moravka (6.5.2000) with weight about 2 tons produced so big VLF signal that it was observed in the distance of about 400 km from the trajectory. Paper about bolide Moravka will be published in Meteoritics next year.