Earthquake sensors reveal vital information about how hurricanes move and grow
Seismic stations in Louisiana have been found to provide insights into Hurricane Isaac The post Earthquake sensors reveal vital information about how hurricanes move and grow appeared first on Physics World .
Researchers in the US have discovered that sensors designed to record earthquakes can also provide crucial insights into the formation, movement and intensity of hurricanes. Seismic sensors installed in Louisiana for studying the Earth's interior were examined to analyze data collected during Hurricane Isaac's 2012 landfall. While earthquakes and hurricanes differ in their formation, movement and impact, the parameters governing each – and the methods of measurement – are distinct.
Hurricanes, which form over warmer tropical and subtropical ocean waters, are characterized by a calm central "eye," surrounding tall thunderstorms, and strong winds called the "eyewall." Meteorologists use three main parameters – track, intensity, and wind radius – to describe hurricane structures and evolution. However, the turbulence in the lower layer is especially important for forecasting wind intensity and developing weather models.
Traditionally, this data is collected using reconnaissance aircraft, ocean buoys, onshore towers and radar. But these methods are limited by the danger of flying planes into hurricanes, sparsity of onshore towers, and difficulty in continuous monitoring. In the study, researchers from Stanford University processed data from 1700 seismic stations across the US.
These "seismoacoustic" stations, equipped with infrasound sensors and seismometers, recorded pressure fluctuations at the Earth's surface caused by the hurricane's passage. The infrasound sensors measured direct turbulence pressure fluctuations, while seismometers recorded elastic responses. The team found that these data revealed the calm eye and turbulent eyewall, as well as the circular layers of thunderstorms and winds.
They used the seismometer data and other atmospheric sensor data to calibrate a computer model of hurricane turbulence, which provided space-time correlations of pressure fluctuations and matched the recorded pressure spectra. By calculating the Earth's elastic response using the simulated pressure field, the researchers aligned their findings with observed vertical displacement.
More importantly, they discovered that the relevant parameter for calculating the Earth's elastic response to pressure fluctuations is the velocity at which these fluctuations are carried downstream, rather than the near-surface wind speed. The researchers hope this study will encourage the deployment of seismometers and infrasound sensors in areas with sparse coverage, such as the southeastern US.
They also note the growing interest in using "noise" signals from seismic stations for environmental monitoring. Seismoacoustic stations have already been used to study ocean wave energy, tropical storms, and winds. However, the atmospheric imprints of hurricanes are less studied due to smaller amplitudes and potentially more complex nature. The study was published in Science.
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