Superconducting Earthquake Early-warning Device (SEED) for Detection of Prompt Gravity Signals from Earthquake Ruptures
The efficiency of current Earthquake Early Warning Systems (EEWS) is limited by their reliance on seismic waves to carry information about the earthquake source: the P-waves used for earthquake detection travel only moderately faster than the damaging S-waves, which limits the EEW lead time and creates a blind zone for EEW. Harms et al. (Geophys. J. Int. vol. 201, 1416, 2015) proposed to overcome this fundamental limitation by developing an EEWS based on geophysical signals that travel at the speed of light: the transient gravity signals generated by the dynamic solid Earth deformation induced by earthquakes. While gravity signals have been recently detected before P waves using broadband seismometers about 1 min after the rupture onset of M > 8 earthquakes, their expected amplitude at earlier times relevant for EEW is generally very small, much below the sensitivity of current instruments. Here we discuss the design and principle of a Superconducting Earthquake Early-warning Device (SEED) that could meet the target sensitivity proposed by Harms et al. (2015), 8 × 10-16 s-2 Hz-1/2 at 0.2 Hz in gravity gradient spectral density.
The design of SEED will be based on the proven superconducting gravity gradiometer (SGG) technology. To reach the target sensitivity of SEED, which is two and a half orders of magnitude beyond that of our SGG under development, we will scale up the mass and baseline of the SGG and utilize a lower-noise Superconducting Quantum Interference Device (SQUID), which is now available commercially. SEED will consist of four magnetically levitated niobium cylinders with each test mass weighing 10 kg and a baseline of 1.0 m, cooled to 4.2 K by commercial cryocoolers and coupled to SQUIDs through capacitance bridges. By combining the outputs of the four three-axis accelerometers, a full-tensor gravity gradiometer can be constructed with isotropic sensitivity for gravity signals coming from any direction.
Session: Advances in Earthquake Early Warning: Research, Development, Current State of Practice and Social Science II
Type: Oral
Room: Cedar
Date: 4/21/2022
Presentation Time: 11:00 AM Pacific
Presenting Author: Ho Jung Paik
Student Presenter: No
Additional Authors
Ho Jung Paik Presenting Author Corresponding Author hpaik@umd.edu University of Maryland |
Christopher Collins cj1coll@umd.edu University of Maryland |
Zachary Metzler zmetzler@umd.edu University of Maryland |
Peter Shawhan pshawhan@umd.edu University of Maryland |
Lingsen Meng meng@epss.ucla.edu University of California, Los Angeles |
Jean-Paul Ampuero ampuero@geoazur.unice.fr Université Côte d’Azur |
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Superconducting Earthquake Early-warning Device (SEED) for Detection of Prompt Gravity Signals from Earthquake Ruptures
Session
Advances in Earthquake Early Warning: Research and Development
Description