Residents of California may soon find themselves distinguishing between a sonic boom and an earthquake, a challenge that could arise as more rocket launches occur in the region. According to Kent Gee, a researcher involved in tracking these events, local citizens have begun reporting their experiences following launches. “Since we’re often setting up in people’s backyards, they text us the results of what they heard,” he noted. “It’s fantastic citizen science. They’ll tell us that the walls shake but the floors don’t. They’re starting to recognize the differences between an earthquake and a sonic boom from a launch.”
Launch trajectories of Falcon 9 rockets along the California coast.
Credit: Kent Gee
The trajectory of a rocket is a crucial factor in determining how sonic booms are experienced. Gee explained that while everyone witnesses the same launch, the sound can vary significantly based on an observer’s location and the rocket’s pathway. “There’s a focal region in Ventura, Oxnard, and Camarillo where the booms are more impactful,” he added. Notably, this focus can change from launch to launch, even if the path remains constant. Meteorological conditions are also influential; seasonal variations in weather may affect how sonic booms propagate due to factors like wind direction, temperature gradients, and topography.
“If you can adjust your trajectory even slightly under the right weather conditions, it can have a major impact on the sonic booms in this area,” Gee stated. The ongoing research project is still in its early stages, with the team collecting data on what they describe as a highly variable phenomenon. “No two launches look the same right now,” said Gee. “It’s like trying to catch lightning.”
As the project continues to evolve, the focus may shift toward social questions and the potential development of science-informed local regulations, such as noise ordinances, aimed at mitigating any adverse effects from launches. The next phase involves modeling sonic booms under various weather conditions, a task that presents challenges due to the diverse microclimates along the California coast. “If you’ve ever driven along the California coast, the weather changes dramatically. You can go from complete fog at Vandenberg to bright sunshine in Ventura County within just 60 miles,” Gee observed.
