Crustal Heterogeneity of the Bhutan Himalaya: Insights from <i>PgQ</i> Tomography

Abstract We present the results of a seismic investigation conducted in Bhutan using data from the Geodynamics and Seismic Structure of the Eastern Himalaya Region broadband network, focusing on variations in crustal structure and seismic attenuation properties. Through analysis of seismic data from 56 events recorded between 2013 and 2014, with magnitudes exceeding 4.5 and depths shallower than 50 km, we examined 1 Hz PgQ (Q0)-values among multiple station pairs using the two-station method. Our findings reveal significant disparities in PgQ0-values across Bhutan. The western region exhibits low PgQ0 values, indicating high seismic attenuation, whereas the central region shows medium-to-high PgQ0 values, suggesting lower attenuation. Notably, these results are consistent with the geometry of the Moho, providing valuable insights into crustal geometry and rheology. This study contributes to a deeper understanding of Bhutan’s complex crustal structure, offering insights into crustal properties and seismic attenuation mechanisms in this geologically significant region.