The Martian hemispheric dichotomy is delineated by significant differences in elevation and crustal thickness between the Northern Lowlands and Southern Highlands. Yet, its origin remains controversial. Here, we improve the signal-to-noise ratios and determine the locations of the low-frequency marsquakes recorded during the InSight mission. We find a new cluster of marsquakes in Terra Cimmeria, Southern Highlands, in addition to those previously located in Cerberus Fossae, Northern Lowlands. Using the spectral ratio method, we estimate the quality factor Q in the range 481–543 for Terra Cimmeria versus 800–2,000 determined for Cerberus Fossae. The attenuation difference might be linked to the temperature differences between the two hemispheres, along with more vigorous convection beneath the Southern Highlands. These seismological observations, together with geochronological constraints of giant impacts, reinforce the “endogenic” hypothesis that mantle convection causes the crustal dichotomy.

中文翻译：

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南部高地火星地震火星二分法起源的约束


火星半球二分法由北部低地和南部高地之间海拔和地壳厚度的显着差异来描绘。然而，它的起源仍然存在争议。在这里，我们提高了信噪比，并确定了 InSight 任务期间记录的低频火星地震的位置。除了之前位于北部低地 Cerberus Fossae 的火星地震之外，我们还在南部高地的 Terra Cimmeria 发现了一组新的火星地震。使用光谱比法，我们估计 Terra Cimmeria 的品质因数 Q 在 481-543 范围内，而 Cerberus Fossae 的品质因数 Q 为 800-2,000。衰减差异可能与两个半球之间的温差以及南部高地下方更剧烈的对流有关。这些地震观测结果，加上巨大撞击的地质年代学限制，强化了地幔对流导致地壳二分法的“内生”假说。