The seismic, geodetic, and tsunami observations are utilized to investigate the October 30th 2020 Samos, Greece earthquake. We adopt back projection (BP) and multi-point source (MPS) techniques to determine the rupture directivity and focal mechanism change of this event. Both methods reveal a unilateral rupture propagation to the west of the epicenter, and also resolve a changed focal mechanism. We use a two-segment-faults geometry to parameterize the fault model with strikes at 283^° for the east segment and 250^° for the west respectively, and conduct a finite fault inversion (FFI) combining seismic and geodetic observations. The kinematics results indicate the whole rupture process lasts about 25 s, yielding a total seismic moment of 3.16×10¹⁹ Nm (M_w = 6.9) with a peak moment rate reaching 3.1×10¹⁸ Nm/s around 10 s. The rupture is composed of two asperities separated by the junction of two fault planes. The main slip area, with maximum amplitude reaching three meters, distributes at a shallow depth and displays a complementary pattern with aftershocks. The slip in the first six seconds is dominated by a pure normal faulting mechanism, while the following rupture includes an additional strike-slip component. The change of focal mechanism reflects the tectonic transition from dilatation to lateral shearing, which is also evident in the aftershock mechanisms. The synthetic tsunami waves also well fit three tidal gauge observations. The coseismic Coulomb stress is calculated to analyze the relationship between the mainshock and aftershock evolution. The mechanism combination of two rupture epochs reflects the combination of shear and dilatational stress status and complicated fault system of the Samos source area.

地震、大地测量和海啸观测用于调查 2020 年 10 月 30 日希腊萨摩斯岛地震。我们采用反投影（BP）和多点源（MPS）技术来确定该事件的破裂方向性和震源机制变化。这两种方法都揭示了向震中以西的单侧破裂传播，并且还解决了改变的震源机制。我们使用两段断层几何参数化断层模型，东段走向为 283 ^{° ，西段走向为 250 °}，并结合地震和大地测量进行有限断层反演（FFI）。运动学结果表明，整个破裂过程持续约25 s，产生的总地震矩为3.16×10 ¹⁹  Nm (M_w = 6.9)，峰值力矩率达到 3.1×10 ¹⁸ Nm/s 大约 10 秒。断裂由两个断层平面的交界处隔开的两个凹凸体组成。主滑动区最大振幅达3米，分布较浅，与余震呈互补格局。前六秒的滑动以纯正断层机制为主，而随后的破裂包括额外的走滑成分。震源机制的变化反映了构造从扩张向横向剪切的转变，这在余震机制中也很明显。合成的海啸波也很适合三个潮汐仪观测。计算同震库仑应力，分析主震与余震演化的关系。