Sciency Thoughts: Jingxi County

Friday, 29 November 2019

Magnitude 5.2 Earthquake in Guangxi Province, China.

The China Earthquake Networks Center recorded a Magnitude 5.2 Earthquake at a depth of 10 km in Jingxi County in Guangxi Province, China, slightly before 9.20 am local time (slightly before 9.20 am GMT) on Monday 25 November 2019. The Earthquake triggered a number of landslides in the area, resulting in one person being killed and four more injured, and was felt across Guangxi Province and northern Vietnam.

A landslide in the town of Hurun in Jingxi County, Guangxi, triggered by an Earthquake on 25 November 2019. Xinhau.

Earthquakes are common in west and southwest China, where the Eurasian Plate is being compressed by the impact of the Indian Plate from the south, but much less common in the east and centre of the country. However southeastern China is in fact dominated by a series of tectonic blocks, annealed onto the Eurasian Plate during the Triassic. Guangxi Province is located on the South China Block, which is being pushed to the southeast by the motion of the Tibetan Block to the northwest and North China Block to the northeast.

Tectonic map of Asia, showing relationships between the India–Asia collision, escape of Indonesian and South China blocks seaward, and extension from Siberia to the Pacific margin. (Note also the opening of back-arc basins including the Sea of Japan and the South China Sea, and extension in the Bohai Basin and eastern part of the NCC.) The North China Craton is also strongly influenced by Pacific and palaeo-Pacific subduction, perhaps also inducing extension in the eastern NCC. The palaeo Pacific and Pacific subduction zones developed in the Mesozoic, and also contributed to the hydration of the subcontinental lithospheric mantle beneath the NCC. Kusky et al. (2007).

Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.

Hedychium viridibracteatum: A new species of Ginger Lily from the Guangxi Autonomous Region of South China.

Ginger Lilies, Hedychium, are a group of 50-80 species of flowering herbaceous plants in the Ginger Family, Zingiberaceae, found predominantly in tropical Asia. They are widely cultivated as both a garden plant and for use as cut flowers, due to their attractive and fragrant flowers. There are currently twelve recognised species found in the Guangxi Autonomous Region of South China, though one of these is divided into two varieties that have recently been shown to have different chromosome numbers, and which should therefore be recognised as separate species.

In a paper published in the journal PhytoKeys on 2 November 2018, Xiu Hu, Jia-qi Huang, Jia-chuan Tan, and Yong-qing Wu, of the Zhongkai University of Agriculture and Engineering, and Juan Chen of the South China Botanical Garden of the Chinese Academy of Sciences, describe a new species of Ginger Lily from the Guangxi Autonomous Region.

The new species is named Hedychium viridibracteatum, in reference to its green bracts and pure white flowers. The species is epilithic (grows on rocks), and is an evergreen perennial rhizomatous herb, producing seven to ten leaves, and a flower spike 10-15 cm high with clusters of pure white flowers in September and October. The plants were found growing on limestone rocks beneath the forest canopy at altitudes of 600-800 m in Napo, Longzhou and Jingxi Counties.