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We have collected broad band seismograms of the earthquakes with magnitudes greater than 4.0 recorded by the Kunming station for the period 1990~2000 and 23 Kunming digital network stations located in Yunnan province for the period 1999~2000. The total 280 Lg coda traces are studied using the stack spectral ratio (SSR) method. Supposing Q of Lg coda correlates with frequency f by Q = Q0fη, the Q value at 1Hz (Q0) and frequency‐related factor η for each record are calculated. Based on the calculated results, the distribution maps of Q0 and η for 0.5°×0.5° cells are obtained using the back‐projection technique. Our results indicate that Q0 in Yunnan and its adjacent regions exhibits low values, varying between 150 and 300. The Q0 in eastern Yunnan is higher than that in western Yunnan. The η varies between 0.3 and 0.8. For most of the regions under study η is within the range from 0.5 to 0.6.

A Curie surface indicates the distribution of the thermal fields underground, providing a clear marker for the thermodynamic effect in the crust and mantle. In this paper, based on a geomagnetic field model (NGDC-720) and aeromagnetic data, we use power spectrum analysis of magnetic anomalies to estimate the Curie surface in Yunnan Province, China, and its adjacent areas. By combining the distribution of the Curie surface with regional heat flow, the geothermal gradient, crustal wave velocity ratio anomalies, high-conductivity layer anomalies, and the Moho surface, we reveal the connection between the undulation of the magnetic basement and the crustal structures. The results indicate that the uplift and depression of the Curie surface in the research area are distinct. The Curie surface is approximately inversely correlated to the surface heat flow. The Lijiang-Jianchuan-Baoshan-Tengchong and Jianchuan-Chuxiong-Kunming-Yuxi zones are two Curie surface uplift zones, and their crust-mantle heat flows are relatively high. The Curie surface uplift zone along the Lijiang-Xiaojinhe fault and Red River fault is consistent with the heading direction of the fault zone and is partially in agreement with the eastward mass flow of the Tibetan Plateau. The Curie surface uplift zone is consistent with the high wave velocity ratio and high-conductivity layer anomaly region of the crust. The depth of the Curie surface is less than the depth of the Moho surface.