Lg attenuation in the central and eastern United States as revealed by the EarthScope Transportable Array

摘要

Lg waveforms recorded by EarthScope's Transportable Array (TA) are used to estimate Lg Q.o in the central and eastern United States (CEUS). Attenuation is calculated based on Lg spectral amplitudes filtered at a narrow band from 0.5 to 1.5 Hz. Two-station and reverse two-station techniques are used to calculate Q_0 values. 39 events occurring from 2010 to 2012 and ranging from magnitude 3 to magnitude 6 are used in this study. 39,258 and 4,627 interstation Q_0 values are determined using the two-station and reverse two-station techniques, respectively. The results show northeast trending high Q_0 regions (low attenuation) ranging from eastern New Mexico to Wisconsin. Regions of low Q_0 (high attenuation) are seen along the Minne sota-Wisconsin border, the Gulf Coastal Plain (GCP), along the South Dakota-Nebraska border, and along the Oklahoma-Texas border. A positive correlation between heat flow, sediment thickness, recent tectonic activity, fluids, and low Q_0 was observed. Areas with low heat flow, thin sediment cover, no recent tectonic activity, and a lack of fluids were observed to have consistently high Q_0. These new models use a greater amount of data, attain more coverage than previous studies, and better constrain attenuation. This increase in detail can improve high frequency ground motion predictions of future large earthquakes for more accurate far field hazard assessment and improve the overall understanding of the structure and assemblage of the CEUS.