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Journal: |
Journal of Geophysical Research 2019 No.8
clicks:188 |
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Title:
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Author:
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Julien Renou |
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Adress: |
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Abstract:
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Observation of the seismic process for a large earthquake population is
of key interest to detect potential magnitude‐dependent behaviors and,
more generally, to quantify how seismic rupture develops. In contrast
with studies focusing on the first radiated waves, we here propose to
characterize the growing phase leading to the main seismic moment
release episode(s), which we refer to as the development phase. Our
analysis uses the 2,221 teleseismic source time functions (STFs) of
shallow dip‐slip earthquakes provided by the global SCARDEC database and
consists in measuring the moment acceleration during the development
phase at prescribed moment rates. This approach is therefore insensitive
to hypocentral time uncertainties and aims at quantifying how seismic
ruptures accelerate, independently of when they accelerate. Our results
first show that rupture acceleration does not exhibit any
magnitude‐dependent signal emerging above the intrinsic measurements
variability. We thus use the full STF catalog to characterize the moment
rate  of the development phase and show that, on average,  with nd equal to 2.7. This time evolution therefore does not follow the steady t2 growth expected for classical circular crack models, which indicates
that stress drop and/or rupture velocity transiently vary during the
development phase. We finally illustrate with a synthetic STF catalog
that, due to initial rupture variability, approaches based on
hypocentral time are not expected to fully characterize the behavior of
the development phase. |
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Comment: |
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