The Tian Shan is one of the most active intracontinental orogenic belts in the world. It has undergone complex deformation that has resulted in the formation of several fold-and-thrust belts (FTBs) in the piedmonts and intermontane basins. Investigating the deformation histories of these FTBs is important for understanding the tectonic propagation processes of the Tian Shan. Here, we gain insight into these crustal shortening processes by deciphering the Houyanshan structure, a typical fold-thrust belt in the eastern Chinese Tian Shan. We first describe a curved thrust ramp and related fold pairs of the structure using high-resolution remote sensing photography, deformation of fluvial terraces, and field-based geological cross-section. Combined with deformed terrace records and optically stimulated luminescence (OSL) dating results, the kinematic style allows us to yield a geologic shortening rate of 1.6 ± 0.2 mm/a since ~52 ka. Second, to reduce uncertainty in the seismic interpretation and quantify the amount and time of crustal shortening, we interpret three seismic reflection profiles by using the theory of quantitative fault-related fold, area-depth-strain (ADS), and reverse modeling analyses. These profiles provide direct evidence that this structure connects by means of a listric thrust ramp to a shallow detachment level. ADS analysis reveals that the maximum shortening of the Huoyanshan structure is ~4.5 km, which is consistent with the result of quantitative inverse modeling. Each of the structural analysis methods gives similar parameters, and the high consistency of results greatly improves the soundness of a given geologic interpretation. Finally, the shortening rate and total shortening amount suggest that the structure may have formed at 1.8–3.7 Ma, which is nearly synchronous around the Tibetan Plateau. Together, these results indicate that this combined geological and geomorphological analysis provides greater insight into deformation information than can be achieved by any individual technique in studying fold-and-thrust belts worldwide.

The 2008 $Mw$ 5.2 Mt. Carmel earthquake is the largest earthquake in the last 50 yrs in southeastern Illinois, near the north termination of the north‐northeast‐trending Wabash Valley fault system (WVFS). The earthquake shows almost pure strike‐slip focal mechanism, but it is still uncertain which nodal plane (NP) is the ruptured fault plane. To resolve the fault plane, we determine rupture directivity of the earthquake via the relative centroid method. We begin with inverting the point‐source solution (strike 297°/dip 84°/rake 1° for NP1, strike 206°/dip 89°/rake 173° for NP2, and centroid depth 16 km) and then determine the relative location between the centroid and hypocenter via regional waveform fitting. Two M 4+ aftershocks are used as reference events, and the waveform time shifts of reference events with respect to the 1D velocity model are used to calibrate the path effects. The results show that the Illinois mainshock ruptured to east‐southeast along the 297° NP for about 2–3 km, consistent with relocated aftershock distribution, and we infer that the sinistral causative fault connects the north‐northwest‐trending La Salle anticlinal belt and the north‐northeast‐trending WVFS.

The quantity and quality of remote sensing measurements of tectonic deformation have increased dramatically over the past two decades, improving our ability to observe active geomorphological tectonic processes. High-precision and high-resolution topography is the basis for the quantitative study of active geomorphological and tectonic processes. Recently, with the rapid development of computer visual science and the growing application of light detection and ranging (LiDAR), small unmanned aerial vehicles (UAVs) and structure from motion (SfM) photogrammetry have shown great potential in providing high-resolution and high-precision topographic information. In this Special Issue, we focus on the tectonic activity of active faults and the geomorphic processes in various global tectonic regimes that are related to remote sensing measurements. This Special Issue covers major earthquake hazards and seismogenic structures, new methods in seismological studies using high-resolution data sets, and the tectonic and geomorphic application of high-resolution data sets worldwide and, in particular, in the Eastern Tibetan Plateau and Tian Shan. These contributions will provide new insights into the remote sensing perspectives of geomorphological and tectonic processes.

Over the past 424 years, the Littoral Fault Zone (LFZ), located offshore of the South China coast, has experienced four destructive earthquakes (M ≥ 7). These events have resulted in an approximately 700 km seismic gap centered on the Greater Bay Area of China, home to over 70 million people. Despite previous studies on deeper crustal structures and geodynamic processes, the shallow structural architecture and recent tectonic activity of the LFZ within the seismic gap remain poorly understood due to limited offshore geophysical investigations. Here, we present new offshore geophysical data to explore the shallow crustal architecture and Holocene activity of the LFZ within this seismic gap. Multichannel seismic data reveal that the LFZ comprises a high-angle listric main normal fault along with several secondary normal faults. The main fault trends northeast and dips southeast in the shallow crustal architecture, serving as the basin-controlling fault in the north of the Pearl River Mouth Basin, with accumulated displacements ranging from 1.5 to 1.8 km. Furthermore, analysis of single-channel seismic data, and ¹⁴C dating results from the borehole, indicate that the most recent movement of the main fault occurred within the last ~10,000 years, with minimum vertical offsets of 1.2 m. Based on these findings, we emphasize the LFZ’s potential to generate a significant earthquake, estimated at M_w 7.0–7.5, within the inferred seismic gap. Our study highlights the potential earthquake hazard posed by the LFZ to the Greater Bay Area of China, while also providing valuable insights for the assessment of active submarine faults worldwide.

鉴识南海北部历史上大规模海啸灾害事件及其指示特征与影响区域，对沿海地区海啸灾害的预测、评估和防范具有重要意义。现有南海北部古海啸灾害研究多集中于沿海陆地或海岛上零星保存的事件沉积物，而对沉积环境相对稳定、且不易受后期改造破坏的浅海沉积物关注很少。本文以汕头海门镇和惠州三门岛外海B01和D02钻孔的浅海岩芯为研究对象，通过沉积物粒度分析、地球化学指标、沉积环境和加速器质谱(Accelerator Mass Spectrometry, AMS) 14C年代测定等，分别在B01和D02岩芯的~195-228 cm和72-105 cm深度鉴别出了“海啸事件沉积层”。两个岩芯的事件层有着相似的形成年龄，介于公元1048-1108年的北宋年间。该层平均粒径较上下层位显著增加，显示为正粒序单层沉积结构、未见平行或交错纹层。层内贝壳碎屑丰富、“新老”共存，其沉积物特征性地球化学指标明显不同于上下层位，且在界面附近地球化学元素含量或元素比值呈现突变规律。综合南海内部及其周缘同期海啸或疑似海啸记录与历史文献记载，认为南海北部上千公里沿岸一带可能发生了与菲律宾、西沙和南沙群岛近同时的海洋巨灾事件。如此空间规模的极端灾害很可能代表了北宋年间的超级海啸事件，其触发机制应主要受控于该时期马尼拉俯冲带Mw >8.0的超强地震。