WANG Xia, senior engineer, majors in seismicity and comprehensive prediction, E-mail: 365372858@qq.com
Using the arrival time data of natural earthquakes from January 2009 to June 2023 in Shanxi and adjacent areas, the double-difference tomography method was employed to obtain the relocated catalog of the region, as well as high-resolution three-dimensional crustal velocity structure and velocity ratio structure. The tectonic environment for historical earthquakes of magnitude 6 or above in this area was discussed. The two-dimensional profiles of velocity and velocity ratio versus depth for historical earthquakes of magnitude 6 or above that passed through the southern part of Shanxi show that the 1303 Hongtong earthquake of magnitude 8 occurred on a gradient belt of high and low velocity anomalies, with a low-velocity anomaly beneath the earthquake, indicating that the ductile creep of the lower-middle crust can lead to localized stress and strain concentration in the brittle upper crust, triggering earthquakes. The earthquake is located in an area of low velocity ratio, and the Linfen basin has a low velocity ratio beneath it, with slightly higher velocity ratios on both sides of the mountainous areas, which is related to the process of crustal extension and thinning beneath the basin. Both the velocity and velocity ratio structures show that the structural characteristics beneath Luoyunshan piedmont fault are steep in the shallow part and gentle in the deep part, with the fault cutting extending to a depth of about 30 km, which is similar to the results of existing seismic reflection profiles and may be the reason for multiple earthquakes of magnitude 6 or above in this area. Most historical earthquakes in the southern part of Shanxi occurred near the gradient belt of high and low velocity ratios, which may be related to these areas being located at the boundary of the basin and mountain, where the crustal material composition changes more dramatically and is more likely to accumulate stress and strain, thus generating earthquakes.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |