For 2 years, the InSight lander has been recording seismic data on Mars that are vital to constrain the structure and thermochemical state of the planet. We used observations of direct (P and S) and surface-reflected (PP, PPP, SS, and SSS) body-wave phases from eight low-frequency marsquakes to constrain the interior structure to a depth of 800 kilometers. We found a structure compatible with a low-velocity zone associated with a thermal lithosphere much thicker than on Earth that is possibly related to a weak S-wave shadow zone at teleseismic distances. By combining the seismic constraints with geodynamic models, we predict that, relative to the primitive mantle, the crust is more enriched in heat-producing elements by a factor of 13 to 20. This enrichment is greater than suggested by gamma-ray surface mapping and has a moderate-to-elevated surface heat flow.

两年来，洞察号着陆器一直在记录火星上的地震数据，这些数据对于限制行星的结构和热化学状态至关重要。我们使用来自八个低频地震的直接（P和S）和表面反射（PP、PPP、SS和SSS）体波相位的观测，将内部结构限制在 800 公里的深度。我们发现了一种与低速带相容的结构，该低速带与比地球上厚得多的热岩石圈相关，这可能与弱S-远震距离的波影区。通过将地震约束与地球动力学模型相结合，我们预测，相对于原始地幔，地壳中产热元素的富集程度是 13 到 20 倍。这种富集程度大于伽马射线表面映射和具有中到高的表面热流。