Download 7-06 Garces Le Pichon - Laboratory for Atmospheric Acoustics

Infrasound Technology Workshop, Bermuda
Section 6. Infrasound from Geophysical Sources
Chairs: Milton Garces and Alexis Le Pichon
Infrasound from Bolides
Meteor research showed a mature integration of imaging, radar, and infrasound
technologies in an automated operational system, allowing a better statistical
assessment of bolide detections and physical parameters. There appears to be
substantial improvements in source models, with an introduction of a quasi-ballistic
component of the radiated sound field. There seems to be a higher bolide incidence rate
and a lower detection threshold than previously anticipated. New neural network
implementations may help optimize the detection and recognition of meteor events.
There appears to be good agreement between theory and observations up to 100g for
size and speed of meteors. Revisited historical events for larger bolides and validated
and refined previous yield relationships.
The compelling evidence provided by the falling cyclist, the unbroken shed, the bull with
a broken horn, and the standing man incriminated the rapidly falling rock. Infrasound
recordings provided the essential evidence to seal the case. The remarkable survival of
the rock upon entry remains exceptional, and may shed insight into similar cases in the
outer planets. Different methods has been applied, provide similar results.
Infrasound Technology Workshop, Bermuda
Section 6. Infrasound from Geophysical Sources
Chairs: Milton Garces and Alexis Le Pichon
The 2008TC3 Sudan bolide, although not exceptional in size and yield, is the first
predicted bolide impact. Lot of observations. Provides a unique and unprecedented
ground truth event for yield relations.
Many interesting presentations demonstrating the potential of a continuous infrasound
monitoring. The IMS network has multiple geophysical applications for the monitoring of
volcanic eruptions, severe weather, bolides, and mass wasting. Microbarom signals may
provide a useful tool for the passive acoustic tomography of the atmosphere, and may
contribute to monitoring climate change at global scales. Monitoring gravity waves may
also provide useful information on the atmospheric dynamics.
The acoustic remote sensing of volcanic eruptions with IMS and regional networks has
progressed substantially. The growing number of stations is allowing a greater collection
of case studies of large eruptions that inject ash into the stratosphere. Preliminary
results suggest that the eruption onset time, duration, and ash height probability of large
eruptions may be reliably inferred from infrasound data.