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Testing a Rotational Seismometer in the Byerly Vault (BKS.BK)

Session: Sensors, Seismicity and Imaging [Poster]

Type: Poster

Date: 4/21/2021

Presentation Time: 11:30 AM Pacific

Description: 

A rotational seismometer, model iXblue BlueSeis 3A, was installed in the Byerly Vault, next to the seismic station BKS.BK operated by the UC Berkeley Seismological Lab, between 2020-03-24 and 2020-06-18. During this interval a variety of broadband translational seismometers were also in operation. This instrument uses three orthogonal optical fiber sensors to measure rotations around the North, East and Vertical axes, sampled at 200 sps, and with a sensitivity of 1 nanoradian/s/count. Its rotational response is flat between DC and 50 Hz, and it nominally has no sensitivity to translational movement. During the deployment, the two largest regional earthquakes were the M6.5 event in southern Idaho (44.465°, -115.118°, 2020-03-31 23:52:30 UTC) and the M6.5 event in the Monte Cristo Range of Nevada (38.169°, -117.850°W, 2020-05-15 11:03:27 UTC) at epicentral distances and azimuths of 943 km and 37°, and 386 and 83° from BKS.BK, respectively. While the Idaho quake was well recorded by all broadband seismometers, it produced signals on the BlueSeis that were only slightly above the rotational noise. Signals from the Nevada mainshock and many aftershocks down to M3.5 were also recorded well by the broadband seismometers, but only the mainshock produced signals on the all three components of the BlueSeis. The clearest and most interesting waveform on the rotational seismometer occurred during a M1.9 earthquake on the Hayward Fault at a depth of 8 km beneath BKS.BK. We present rotational and translational seismograms from these events and discuss our experience with the BlueSeis 3A.

Presenting Author: Margaret Hellweg

Student Presenter: No

Authors