China has a nearly 3000‐year‐long earthquake record listed in various Chinese earthquake catalogs. The magnitudes in those catalogs are expressed in surface‐wave magnitude $Ms$. However, modern seismic‐hazard analysis prefers earthquake catalogs in moment magnitude $Mw$. Here, we compile a homogeneous $Mw$‐based historical earthquake catalog based on three Chinese earthquake catalogs and three global $Mw$ catalogs. For post‐1900 earthquakes, we compare the common events with $Ms$ in Chinese catalogs and with $Mw$ in global catalogs, and derive $Ms–Mw$ regression relationships using a constrained general orthogonal regression method. The regressions are performed separately over two magnitude ranges ($5.5≤Ms<7.0$ and $Ms≥7.0$) and three time periods (1900–1965, 1966–1975, and 1976–2015) because earthquake monitoring capabilities in China varied over those magnitudes and time ranges. We use the regression results to convert $Ms$ magnitudes in the Chinese catalog to $Mw$ magnitudes. For pre‐1900 events, we apply the regression results of the 1900–1965 period because the $Ms$ values of the pre‐1900 events were converted from shaking intensity, and the $Ms$‐intensity relationships were derived from the post‐1900 earthquakes. We also add earthquakes from other catalogs to obtain a more complete $Mw$‐based catalog for China. The final catalog has about 15,700 earthquakes of $Mw≥4.0.$ The catalog is more complete for eastern China than western China because eastern China has a much longer history of human settlement.

Magnitude‐rupture scaling relations describe how the length, width, and area of fault rupture vary with earthquake magnitude. These parameters are required in seismic hazard models to fit the models’ earthquakes onto faults and to define the site‐rupture distances needed in ground‐motion prediction equations. We collected the magnitude and rupture parameters of 91 earthquakes in Mainland China and nearby regions to study magnitude‐rupture scaling relations. We find no systematic deviations for the subsurface rupture length (RLD) obtained from different methods versus earthquake magnitude. We performed regressions of RLD versus magnitude and versus rupture width using general orthogonal regression. Then, we derived the relations between rupture area and magnitude. Our relations are not statistically different from the results derived by others using global datasets, if the parameters of the five pre‐1900 great earthquakes in eastern China are not used. However, if the five earthquakes are used, the magnitude‐rupture length scaling relation for large strike‐slip earthquakes in eastern China gives shorter rupture lengths than earthquakes in western China and other plate boundary regions in the world.

The Xianshuihe fault is a remarkable strike‐slip fault characterized by high slip rate (⁠ $∼10mm/yr$⁠) and frequent strong historical earthquakes. The potential for future large earthquakes on this fault is enhanced by the 2008 $Mw$ 7.9 Wenchuan earthquake. Previous works gave little attention to the probabilities of multisegment ruptures on the Xianshuihe fault. In this study, we build five possible multisegment rupture combination models for the Xianshuihe fault. The fault slip rates and historical earthquakes are used as input constraints to model the future seismicity on the fault segments and test whether the rupture combination models are appropriate. The segment combination model, based essentially on historical ruptures, has produced the seismicity rates most consistent with the historical records, although the model with ruptures on both the entire northern section and southern section should also be considered. The peak ground acceleration values with a return period of 475 yr calculated using the modeled rates on the Xianshuihe fault for both two models are on average larger than the values of the China Seismic Ground Motion Parameters Zonation Map.

The establishment of a regional historical landslide inventory plays an indispensable role in landslide assessment and prevention. In this study, based on the Google Earth platform, an inventory of ancient landslides in Hualong County, Qinghai Province was established. The inventory includes 3517 ancient landslides with individual areas ranging from 2354.6 m² to 12.44 km². The dominant characteristics include an elevation of 2600–2800 m, slope of 10–20°, aspects SW, W, and NW, mudstone and sandstone of Paleoproterozoic, Neoproterozoic and Quaternary loess, 8–10 km from faults, 0–1 km from rivers, cultivated and grassland types, NDVI of 0.25–0.3, and an average precipitation in the range of 480–500 mm. In addition, the geometric analysis of landslides shows that the average height and length of ancient landslides in the study area are 151.92 m and 429.52 m, respectively. The power law relationship between the two is L = 0.41 × H^1.37. The ancient landslide inventory of this study exhibits an integrated pattern of the development characteristics and spatial distribution of landslides in the Tibetan Plateau and the upper Yellow River basin, as well as providing a significant reference for subsequent landslide susceptibility mapping in the area.