Magnetic Field Variations in Alaska: Recording Space Weather Events on the Transportable Array

Session: Recent Advances in Very Broadband Seismology
Type: Oral
Date: 4/30/2020
Time: 11:00 AM
Room: 215 + 220
Description: 

Seismometers are highly sensitive instruments to not only ground motion but many other non-seismic noise sources (e.g. temperature, pressure and magnetic field variations). Because magnetic flux variations are stronger at high latitudes, the Alaska component of the Transportable Array (TA) is particularly susceptible to recording space weather events. We show that vertical-component seismic records across Alaska are directly recording magnetic field variations between 40 to 800 s period, as opposed to ground motion during strong geomagnetic/auroral events. Using co-located magnetic field records, it is possible to remove this signal from the seismic record and attain as much as 10 dB in noise improvement. However, this correction does not work across large spatial distances (e.g. greater than 200 km) and the magnetometer network in Alaska is sparse. We demonstrate that low-cost magnetometers, such as the Bartington Mag-690, are capable of recording magnetic field signals with a signal-to-noise ratio similar to observatory-grade magnetometers, operated by the U.S. Geological Survey Geomagnetic Program, at periods below 1000 s. However, the accuracy of these low-cost magnetometers must be better constrained. Deploying low-cost magnetometers at seismic stations could provide a unique opportunity to reduce long-period vertical seismic noise as well as increase the spatial resolution of magnetic field observations.

Presenting Author: Adam T. Ringler

Authors