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Historical records truthfully document human life and activities associated with climate and environmental changes. Based on the official historical records for the years 1–1911 Common Era (i.e., a period of 1911 years), we examine how the 408 epidemic events, occurring in 282 years, are related to solar activity, geographical locations, seasons, and natural disasters of anomalous temperature and irregular precipitation, in China. The epidemics occur more frequently during the low solar activity period. The inland area and area north to the climate boundary of Qinling–Huaihe Line along 35° geographic latitude, in particular, suffer epidemics more often during low solar activity periods. In fact, 45% or more epidemics occurred in summer, while less than 9% occurred in winter. The infection is highly related to social distancing, and therefore the epidemics also occur likely in areas with high-density population or heavy traffic. Statistical tests further demonstrate that natural disasters owing to anomalous temperature and irregular precipitation act as mediators which significantly cause the epidemics in ancient China. [ABSTRACT FROM AUTHOR]

Historical records truthfully document human life and environment associated with climate changes. We quantify official historical records of China dating back last 2000 years to examine the disasters due to anomalous temperatures of cold or hot, irregular precipitations of wet or dry, and floods in inland/coastal or Northern/Southern areas in four seasons that possibly linked to solar activities during 1-1825 CE (Common Era). It is found that the proportion of disaster years is positively associated with the time periods, and therefore, both the cases with high and low solar activity (HSA and LSA) leading are under study. Statistical results show that extreme cold weather occurs particularly in the Winter and Spring during LSA periods. Irregularities precipitations, including heavy rain/hail/snow and severe drought are significantly frequent during LSA periods, while floods on inland and coastal river basins tend to occur more frequently in LSA and HSA periods, respectively. The disasters owing to irregularities precipitations and floods frequently happen in Summer and Autumn, which suggests that the irregular precipitations could cause the floods. All the disasters occur significantly in the Northern China, which suggests the climate boundary of the Qinling–Huaihe Line along at about 33°N being essential. In total, all the disasters due to the anomalously cold temperatures, irregular precipitations, and floods tend to occur during the LSA periods. [ABSTRACT FROM AUTHOR]

To adaptively forecast forthcoming large aftershocks of the 2008 Mw7.9 Wenchuan, China, earthquake, we construct a new hazard model to describe the occurrence rate of aftershocks in a study region along the Longmenshan fault. The model is denoted by SRJ since it is a combination of the Reasenberg–Jones (RJ) model and a spatial hazard model that is obtained by taking a reference of previous earthquakes in the study region. We employ the maximum likelihood (ML) method to estimate the SRJ model based on aftershocks that occurred within 1 or 2 days after the Wenchuan earthquake. The probabilities of M ≥ 5.0 aftershocks at each of the grids in the study region during next few days are then computed according to the estimated SRJ model, and hence the corresponding relative aftershock hazard (RAH) map is constructed. Finally, according to a variety of criteria for evaluating the hazard maps on depicting possible rupture area of forthcoming large aftershocks, the SRJ-based RAH map is demonstrated to be more efficient than the RAH maps constructed based on the RJ model incorporated with the gridding method using a fixed radius or varying radii. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, 240 abnormal infrasound signals observed at Beijing (39.87°N, 116.48°E) and 92 M ≧7.0 worldwide earthquakes during 2002–2008 are investigated. It is found that about 85% the earthquakes are preceded the signals by 1–30days and the greater M ≧7.6 earthquakes are most likely leaded by 1–10days. The maximum amplitude of the abnormal infrasound signal generally exceeds 8Pa in sound pressure. The statistical analyses further indicate that the amplitude of the abnormal signals is proportional to the magnitude the associated forthcoming earthquake but inversely to the distance from that earthquake to the observation station. [Copyright &y& Elsevier]

In this paper, the total electron content (TEC) of Global Ionosphere Maps (GIMs) is normalized and employed to study the seismo-ionospheric anomalies at the time of the 12 May 2008 M 8.0 Wenchuan Earthquake. The space weather conditions are taken into account. It is found that remarkable reductions appear locally around the epicentre and their conjugate points during the daytime of 29 April and 6-10 May 2008. A global study and a strict criterion are applied to detect anomalies. Results show that the anomalies on 29 April and 6 and 7 May 2008, which are respectively days 13, 6 and 5 before, are possibly related to the earthquake. The conjugate signature implies the seismo-generated electric field is essential. [ABSTRACT FROM AUTHOR]

Changes in the underlying conductivity around hypocenters are generally considered one of the promising mechanisms of seismo-electromagnetic anomaly generation. Parkinson vectors are indicators of high-conductivity materials and were utilized to remotely monitor conductivity changes during the MW 6.5 Jiuzhaigou earthquake (103.82°E, 33.20°N) on 8 August 2017. Three-component geomagnetic data recorded in 2017 at nine magnetic stations with epicenter distances of 63–770 km were utilized to compute the azimuths of the Parkinson vectors based on the magnetic transfer function. The monitoring and background distributions at each station were constructed by using the azimuths within a 15-day moving window and over the entire study period, respectively. The background distribution was subtracted from the monitoring distribution to mitigate the effects of underlying inhomogeneous electric conductivity structures. The differences obtained at nine stations were superimposed and the intersection of a seismo-conductivity anomaly was located about 70 km away from the epicenter about 17 days before the earthquake. The anomaly disappeared about 7 days before and remained insignificant after the earthquake. Analytical results suggested that the underlying conductivity close to the hypocenter changed before the Jiuzhaigou earthquake. These changes can be detected simultaneously by using multiple magnetometers located far from the epicenter. The disappearance of the seismo-conductivity anomaly after the earthquake sheds light on a promising candidate of the pre-earthquake anomalous phenomena. [ABSTRACT FROM AUTHOR]

Scientists investigating the coupling between the lithosphere, atmosphere, and ionosphere (LAI) require multiple instruments installed on and near the Earth's surface and aboard satellites orbiting the Earth. However, challenges always occur owing to a lack of observation data from other monitoring instruments and/or the distance between distinct instruments. A novel system for monitoring vibrations and perturbations in the LAI (MVP–LAI) was established in the countryside of Leshan City, Sichuan Province, China, in June 2021. Twelve different types of instruments with 18 devices were set within an area of 50 m × 50 m. The other two were installed approximately 20 km away to avoid interference. These instruments routinely monitor the changes in at least 14 geophysical parameters with short sampling intervals, available for capturing waves propagating from the subsurface to the ionosphere. Once the observations retrieved from the China Seismo-Electromagnetic Satellite and the radio occultation are integrated, the monitoring of vibrations and perturbations can reach ~ 800 km above the Earth's surface. The system is mainly operated by the China University of Geoscience (Wuhan), China and will officially start functioning in September 2021. All the efforts benefit the investigation of the causal mechanisms of LAI coupling and expose the potential sources of vibrations and perturbations, incorporating observations from other spheres. [ABSTRACT FROM AUTHOR]