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meichenl@umich.edu
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- Creator:
- Liu, Meichen
- Description:
- The raw seismic records are downloaded from Incorporated Research Institutions for Seismology. The facilities of IRIS Data Services, and specifically the IRIS Data Management Center, were used for access to waveforms, related metadata, and/or derived products used in this study. The synthetic seismograms are generated by SPECMFEM3D_Globe software which was downloaded from the Computational Infrastructure for Geodynamics ( https://geodynamics.org/).
- Keyword:
- Composition and structure of the mantle, Phase transitions, North America, Body waves, and Computational seismology
- Discipline:
- Science
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- Creator:
- Liu, Meichen
- Description:
- We intend to figure out the difference of stress drops, which is a characteristic source parameter, between shallow and deep-focus earthquakes. Significant stress drop difference may shed light on the difference of physical mechanisms of shallow and deep-focus earthquakes, which has been a elusive question. We select from deep-focus earthquakes (> 400 km) in 2000-2018 and obtain their stress drops using P and S waves. We find that stress drops of deep-focus earthquakes are about one order of magnitude higher than that of shallow earthquakes, indicating about one order of magnitude higher shear strength of shallow faults than faults in the mantle. The wide range of stress drops further suggests coexistence of phase transformation and shear-induced melting mechanisms of deep-focus earthquakes.
- Citation to related publication:
- Liu, M., Huang, Y., & Ritsema, J. (2020, March 4). Stress drop variation of deep-focus earthquakes based on empirical Green's function [preprint]. Submitted to Geophysical Research Letters. https://doi.org/10.31223/osf.io/8jx6p and Liu, M., Huang, Y., & Ritsema, J. (2020). Stress Drop Variation of Deep-Focus Earthquakes Based on Empirical Green’s Functions. Geophysical Research Letters, 47(9), e2019GL086055. https://doi.org/10.1029/2019GL086055
- Discipline:
- Science
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An analysis of recorded and simulated SH wave reverberations in the upper mantle beneath the USArray
- Creator:
- Meichen Liu
- Description:
- We use waveform data from the USArray and spectral-element method synthetics for 3-D seismic models. The recorded waveform data are downloaded from Incorporated Research Institutions for Seismology (IRIS) which is open to everyone. The synthetic waveform data are generated by the SPECMFEM3D_Globe software that was downloaded from the Computational Infrastructure for Geodynamics ( https://geodynamics.org/). This dataset includes the scripts we use to automatically download data from IRIS, the selection of data, and the application of the CRP method. In doing this, we use the TauP toolkit which is free to download ( https://www.seis.sc.edu/taup/) to compute the travel time.
- Keyword:
- seismology
- Discipline:
- Science
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- Creator:
- Liu, Meichen
- Description:
- The Brune source model is widely used in studies of complex earthquakes with multiple episodes of high moment release (i.e., multiple subevents). In this study, we investigate how corner frequency estimates of earthquakes with multiple subevents are biased if they are based on the Brune source model. By assuming complex sources as a sum of multiple Brune sources, we analyze 1,640 source time functions (STFs) of Mw 5.5-8.0 earthquakes in the SCARDEC catalog to estimate the corner frequencies, onset times, and seismic moments of subevents. We identify more subevents for strike-slip earthquakes than dip-slip earthquakes, and the number of resolvable subevents increases with magnitude. We find that earthquake corner frequency correlates best with the corner frequency of the subevent with the highest moment release (i.e., the largest subevent). This suggests that, when the Brune model is used, the estimated corner frequency and therefore the stress drop of a complex earthquake is determined primarily by the largest subevent rather than the total rupture area. and Our results imply that the stress variation of asperities, rather than the average stress change of the whole fault, contributes to the large variance of stress drop estimates.
- Citation to related publication:
- Meichen Liu, Yihe Huang, Jeroen Ritsema. 2021. Characterizing Multi-Subevent Earthquakes Using the Brune Source Model [Preprint]. https://essoar.org (2021) DOI: doi.org/10.1002/essoar.10507564.1
- Discipline:
- Science