Seismic shaking has been regarded as an essential source of resurfacing on asteroids. The Small Carry‐on Impactor (SCI) operation on Hayabusa2 has been expected to be a unique opportunity for testing in situ seismic shaking whose energy is sufficiently large to excite observable surface modification. However, no obvious regolith hopping was identified even immediately outside of the crater formed by the SCI impact. To understand this discrepancy from the expectation, we simulate seismic wave propagation on Ryugu with a wide range of surface material properties and evaluate maximum acceleration on the surface. Numerical results reveal that low‐quality factor or low seismic efficiency is required to explain the lack of geomorphological change after the SCI experiment. Considering that scattering under anhydrous conditions cannot efficiently dissipate energy, such a low‐quality factor is not plausible. The weak yield strength in porous materials can efficiently decrease seismic wave energies, making the apparent seismic efficiency extremely low. Based on this hypothesis, we propose a formulation of surface mobility on asteroids that considers the physical properties of regolith. We consistently estimate the occurrence of seismic shaking with the existence of unstable boulders on Ryugu.

中文翻译：

---

Hayabusa2撞击实验引起的地震波在Ryugu小行星上传播的模拟任务：多孔多孔石的低屈服强度限制了有限的质量传输

地震已经被认为是小行星表面重铺的重要来源。人们期望在Hayabusa2上使用小型随身撞击器（SCI），这将是一次现场地震振动测试的独特机会，其能量足够大，可以激发可观察到的表面改性。但是，即使在由SCI撞击形成的火山口之外，也没有发现明显的重排石屑跳跃。为了从预期中了解这种差异，我们模拟了Ryugu地震波在具有广泛表面材料特性的情况下的传播，并评估了表面上的最大加速度。数值结果表明，在SCI实验之后，需要低质量因数或低地震效率来解释缺乏地貌变化。考虑到在无水条件下的散射不能有效地耗散能量，因此这种低品质因数是不合理的。多孔材料的弱屈服强度可有效降低地震波能量，从而使表观地震效率极低。基于此假设，我们提出了一种考虑小块体物理特性的小行星表面迁移率公式。我们一直估计龙古岛上存在不稳定的巨石，从而产生地震震动。我们提出了一种考虑到重碎石物理特性的小行星表面迁移率公式。我们一致地估计了龙古岛上不稳定石块的存在引起的地震震动的发生。我们提出了一种考虑到稀土元素的物理特性的小行星表面迁移率的公式。我们一直估计龙古岛上存在不稳定的巨石，从而产生地震震动。