Chile2015: Induced Magnetic Fields on the Z Component by Tsunami Wave Propagation

摘要

This study reports the magnetic disturbances due to the Chilean tsunami (2015). Using 10 ground-based magnetometer observatories spread in the Pacific Ocean, covering approximately epicentral distance, for a time duration of 24 h from the tsunami initiation, tsunamigenic disturbances in the Z-component of the geomagnetic field are investigated. The methodologies namely, the discrete wavelet transform (DWT), the newly developed approach called effectiveness wavelet coefficient (EWC), and intrinsic mode functions (IMF) decomposition are implemented to detect these tsunamigenic disturbances. The analysis reveals the presence of an increase of EWC amplitude due to tsunamigenic magnetic disturbances nearly around the tsunami arrival time at each observatory. The IMF decomposition analysis using 10-40 min levels of decomposition shows the amplified magnetic disturbances around the time of the increase in EWC amplitude. In most of the observatories, the time of the amplified EWC is consistent with the approximate time of the tsunami arrival, while in the other observatories, the IMF decomposition provides better consistency. The results suggest that the methodologies implemented in the present work can be effectively used to characterize the tsunamigenic contributions in the geomagnetic field, since the tsunami wavefront propagates towards the Pacific Ocean covers the time duration as long as 24 h from the tsunami initiation.