There exists much debate about origins of Cretaceous to present volcanism in northeast (NE) China. Here we present high‐resolution seismic images of the upper mantle beneath NE China obtained by inverting P wave traveltime data recorded by two dense linear arrays. The inclusion of the new data set has greatly improved sampling of the upper mantle beneath the study region, providing tight constraints on the seismic structure under the intraplate Wudalianchi and Halaha volcanoes. Local‐scale low P wave velocity (low‐Vp) anomalies are revealed in the shallow mantle beneath the two volcanoes, whereas a large‐scale high‐Vp zone is imaged in the mantle transition zone. These new results suggest that the two volcanoes, though located at different sites above the stagnant Pacific slab in the mantle transition zone, are likely related to the deep subduction and dehydration of the Pacific slab, possibly through hot and wet upwelling in the big mantle wedge beneath Wudalianchi and through deeper hydrous upwelling related to slab avalanche beneath Halaha. Our results also reveal other striking features, such as high‐Vp anomalies resting atop the 410‐km discontinuity beneath the Great Xing'an Range and the Songliao Basin, which are attributed to detached continental lithosphere. The delamination most likely occurred in the Cretaceous, which induced widespread magmatism in NE China.

Typhoon, as one of the extreme climatic disasters, attacks the southeast coastal cities in China every year. To countermeasure the risk of a typhoon on urban tree safety, we established a cooperation research team including professions on urban design and city planning, wind engineering, and tree health assessment and management. This paper presents some statistical studies on the data of the damaged urban trees causing by the typhoons in Guangzhou and some other cities in Pearl River Delta (PRD), China in 2016 - 2018. The data of the damaged trees is imported in a geographic information system (GIS) database and a local climate zone (LCZ) map to analyze the distribution of damaged trees in different urban morphologies and underlying surface patterns. Results show a series of high-risk tree species such as Ficus microcarpa, Ficus virens var.sublanceolata, and Bauhinia variegate in typhoons. Then, six LCZ typologies and four main typologies of urban space are figured out basing on the statistical analysis of the damaged trees. Preliminary results reveal that some kinds of tree species and urban space are at a higher risk level during the typhoons. Current works will support the research on urban tree management, risk management and forecasting, urban planning, and landscape design.

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