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Direct Comparison of the Tsunami‐Generated Magnetic Field With Sea Level Change for the 2009 Samoa and 2010 Chile Tsunamis
Direct Comparison of the Tsunami‐Generated Magnetic Field With Sea Level Change for the 2009 Samoa and 2010 Chile Tsunamis
- Source :
- Journal of Geophysical Research - Solid Earth; November 2021, Vol. 126 Issue: 11
- Publication Year :
- 2021
-
Abstract
- The motion of conductive seawater by tsunamis can generate magnetic fields in the presence of the background geomagnetic main field. Previous studies found that, using the tsunami‐generated seafloor magnetic field, it is possible to predict the propagation direction and wave height prior to the actual arrivals of tsunamis. This study correlates the tsunami magnetic field and the tsunami sea level change using observed data and three‐dimensional simulations of the 2009 Samoa and 2010 Chile tsunamis. Our direct comparison of the tsunami observed magnetic field and tsunami sea level change illustrate that the vertical tsunami magnetic component, bz, arrived earlier than the sea level change. The “initial rise” signal in the observed horizontal tsunami magnetic component, bh, which was arrived even earlier than bzalso is found by combing the observation with the three‐dimensional simulations. We further examine the precision of conversion of the tsunami magnetic field to the sea level change and find that the magnetic field derived tsunami sea levels are as precise as those obtained from differential pressure gauge data. However, our simulation shows that existing tsunami source models are incompatible with our tsunami magnetic data. Therefore, it is necessary to include magnetic field derived tsunami sea level changes to improve those source models. The tsunami‐generated magnetic field is a magnetic field that appears with movement of seawater by tsunamis. In the previous studies, researchers found that the tsunami‐generated magnetic field arrives earlier than the tsunami sea level change based on analytical solutions and numerical simulations. In this study, we used the world's first simultaneous data of sea level change and magnetic field in the 2009 Samoa and 2010 Chile tsunamis to study the relation between these two physical quantities. We found that the vertical component of tsunami magnetic field arrives earlier than the sea level change. Moreover, the horizontal component of tsunami magnetic field arrives even earlier than the vertical component. We also revealed that the tsunami magnetic field can be used to estimate the tsunami wave height very accurately. We investigated the observed tsunami magnetic field by the 3‐D time domain simulation. However, the currently available tsunami source models were unable to reproduce the observation in our research area. We confirmed that a better source model can improve the simulation. It follows that our high precision tsunami wave height data calculated from the magnetic field can improve the existing tsunami source models. Direct comparison of the observed tsunami magnetic field with tsunami sea level change for the 2009 Samoa and 2010 Chile tsunamisEstimation of the tsunami wave height by the tsunami‐generated magnetic field3‐D time domain simulation of both tsunami sea level change and magnetic field for the 2009 Samoa and 2010 Chile tsunamis Direct comparison of the observed tsunami magnetic field with tsunami sea level change for the 2009 Samoa and 2010 Chile tsunamis Estimation of the tsunami wave height by the tsunami‐generated magnetic field 3‐D time domain simulation of both tsunami sea level change and magnetic field for the 2009 Samoa and 2010 Chile tsunamis
Details
- Language :
- English
- ISSN :
- 21699313 and 21699356
- Volume :
- 126
- Issue :
- 11
- Database :
- Supplemental Index
- Journal :
- Journal of Geophysical Research - Solid Earth
- Publication Type :
- Periodical
- Accession number :
- ejs58338250
- Full Text :
- https://doi.org/10.1029/2021JB022760