AZGS geologists Jeri Young and Phil Pearthree pulled out four of the seven portable seismometers deployed in the area around June's M5.2 earthquake near Duncan, Arizona. The portable instruments were installed in July to monitor the aftershocks from the June 28 event, detect small events, and provide accurate locations for all of the aftershocks.
However, the PASSCAL facility that owns the instruments needs to redeploy them in the Napa California area to monitor the aftershocks from last weeks M6.1 earthquake there.
Since they were installed, the portable instruments have recorded hundreds of aftershocks, with the largest a M4.1 event [right. waveforms of aftershock as recorded by different stations]
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