Simulation of Mining-Induced Ground Damage Using Orthogonal Experiments to Determine Key Parameters of Super-Large Coalface: A Case Study in Shendong Coalfield in China

High-strength mining of super-large coalfaces in the Shendong coalfield causes significant damage to the ground surface. To study the key parameters of undermined coalfaces that affect ground damage, 25 numerical simulation models were designed using an orthogonal experimental method based on the geological and mining conditions of the Bulianta Mine. In the orthogonal design, four factors (the lengths in both the dip and strike directions, the thickness and the mining speed of the coalface) were considered, with five levels designed for each factor. The subsidence displacements and deformations caused by the excavation were then simulated and verified using field surveying data. A damage extent index (DEI) was introduced and used to assess the extent of global ground damage caused by each simulative excavation. Analysis of variance (ANOVA) method was then employed to determine the key parameters of the coalface that significantly influence the ground damage. It was found that the coalface dip length and thickness and the coalface thickness can be regarded as the key parameters for ground objects of building and timberland, respectively. This research provides theoretical and technical support for the coordinated exploitation of resources and environments in Shendong and other similar, ecologically fragile coalfields.

Patterns of earthquake-related mortality at a whole-country level: New Zealand, 1840–2017

Fatalities directly or indirectly attributed to New Zealand earthquakes in the time period 1840–2017 inclusive were identified and classified by context and cause of death. There have been at least 489 deaths primarily attributed to 21 New Zealand earthquakes with Modified Mercalli Intensities (MMIs) of VII or greater, and an additional 11 deaths resulting from secondary earthquake causes (e.g. relief efforts). Earthquake-related deaths were caused by building damage (431 deaths, 88%), ground damage (34 deaths, 7%), or other causes (24 deaths, 5%). Damage to at least 95 unreinforced masonry (URM) buildings resulted in 272 deaths, and damage to five reinforced concrete (RC) buildings resulted in 145 deaths. Daytime earthquakes were more deadly than nighttime earthquakes, and mortality rates showed a significant increase with MMI. Mortality rates were nearly evenly distributed between males and females, the median age of death was 38 years, and the elderly population (>80 years) had the highest mortality rate.

Seismic Vulnerability Maps of Ratu Agung District, Bengkulu City, Indonesia

During the 8.6 Mw Bengkulu-Mentawai Earthquake Ratu Agung District was identified as an impacted area. This paper aims to deliver the seismic vulnerability based on geophysical observation. This study was initiated by performing the ambient noise measurement to obtain the geophysical characteristic, such as amplification and predominant frequency. Furthermore, the vulnerability index analysis was performed from the geophysical information collected from the investigation. To observe the tendency of ground damage during the earthquake, ground damages analysis is also performed. All results are depicted into the microzonation maps. The results showed that the amplification and predominant frequency on site are generally ranging from 3 to 5 and 5 to 8 Hz, respectively. The seismic vulnerability index in study area is up to 10-3. The results showed that during the Bengkulu-Mentawai Earthquake, the investigated sites could be possible to undergo crack settlement which can trigger massive sand boiling in the study area.

Characterization of seismogenic crustal faults in the Gulf of Guayaquil, Ecuador

Few moderate-to-strong earthquakes associated with active and capable geological faults have been documented for the southern coastal region of Ecuador. The seismic record of Ecuador initiates with the Guayaquil earthquake in 1787 (Mw 6.5), followed by the 1943 (Mw 6.2), and the most recent one in 1980 (Mw 6.1). The available data is insufficient to evaluate the seismic hazards associated with faults capable of generating seismic events of magnitude Mw≥6.0 in the region. Also, earthquakes of minor magnitudes can be disregarded as they do not induce significant ground coseismic effects. In this context, this study presents a catalog of geological faults, delineating 40 segments of capable and active faults on the sea floor of the Gulf of Guayaquil and inland segments of Guayas, Santa Elena, and El Oro provinces. This methodological approach estimates a variety of seismicity levels ranging between Mw 6.2 and Mw 7.2, with rock peak ground accelerations between 0.24 g and 0.41 g. These values have been obtained from empirical regression equations applied to the length of capable geological faults. The F-40 seismogenic structure located in the accretionary prism, close to the subduction zone, is capable of generating Mw 8.2 earthquakes and potentially causing coseismic ground damage to the city of Guayaquil located ca. 177 km to the NE. Furthermore, local tsunami hazards may affect severely areas that are densely populated, with developing industrial areas, on the coast of the Gulf of Guayaquil. This structural geological analysis provides useful new data for seismic hazard assessment.

Efek Penggunaan Lahan Terhadap Degradasi Tanah Pada Kebun Campuran Di Kecamatan Kairatu Kabupaten Seram Bagian Barat Propinsi Maluku

Land use is the most influential factor in soil degradation due to erosion. The objectives of this research are to know the level of land degradation and the factors that influence the land use area, the upper vegetation density and the lower vegetation density. This research uses the method of measuring ground damage indicator in the field. The results showed that single, wide land use, upper vegetation density and lower vegetation density had an effect on soil degradation on mixed garden land use; while simultaneously, wide land use, upper vegetation density and lower vegetation density have an effect on soil degradation on mixed garden land use. The most influential factors for soil degradation in mixed gardens are the area of land use and lower vegetation density.Keyword: Degradation of soil, land, vegetation density, mixed gardens.

Pemetaan Status Kerusakan Tanah di Lahan Pertanian di Kecamatan Cepogo Kabupaten Boyolali

<p style="text-align: justify;">Land used in agriculture plays an important role in supporting the production of biomass. Destruction of land for biomass production is changing the nature of the soil that exceeded the standard criteria of soil damage. Mapping of land degradation status is useful to know the condition of the soil and tillage correct action. This study was conducted using a survey in the Subdistrict Cepogo Regency Boyolali. Existing data will be scoring and macthing with standard criteria for biomass production ground damage that Government Regulation No. 150 of 2000. Analysis of the data shows that there is no damage land area covering 744,1 Ha (13,7%) and there are areas relatively lightly damaged by parameters of degradation status, namely the composition of the fraction covering 494,4 ha (9,1%), the degree of release of water parameters covering 294,4 ha (5,4%) and a combination of parameters fraction composition and the degree of release of water covering 1.813 Ha (33, 4%).</p>