Source rupture process of the 2015 Gorkha, Nepal Mw7.9 earthquake and its tectonic implications

On 25 April, 2015, an Mw7.9 earthquake occurred in Nepal, which caused great economic loss and casualties. However, almost no surface ruptures were observed. Therefore, in order to interpret the phenomenon, we study the rupture process of the earthquake to seek answers. Inversion of teleseismic body-wave data is applied to estimate the rupture process of the 2015 Nepal earthquake. To obtain stable solutions, smoothing and non-negative constraints are introduced. 48 teleseismic stations with good coverage are chosen. Finite fault model is established with length and width of 195 km and 150 km, and we set the initial seismic source parameters referring to CMT solutions. Inversion results indicate that the focal mechanism of this earthquake is a thrust fault type, and the strike, dip and rake angle are in accordance with CMT results. The seismic moment is 0.9195 ×10^（21）Nm（Mw7.9）, and source duration is about 70s. The rupture nucleated near the hypocenter and then propagated along the dip direction to the southeast, and the maximum slip amounts to 5.2 m. Uncertainties on the amount of slip retrieved by different inversion methods still exist, the overall characteristics are inconsistent. The lack of shallow slip during the 2015 Gorkha earthquake implies future seismic hazard and this region should be paid more attention to.

Effect of Andalusite Addition on Properties of Chrome-corundum Bricks

In order to improve the thermal shock resistance of chrome-corundum bricks,different amounts of andalusite were added to the formulation of chrome-corundum bricks to replace the equivalent white fused corundum with the same particle size.After mixing,shaping,drying and firing,the density,the cold strength,the cold wear resistance,the hot modulus of rupture and the thermal shock resistance were tested.XRD,SEM and elemental surface scanning were used to characterize the specimens.The results show that:(1)the volume expansion of andalusite mullitization reduces the apparent porosity of chrome-corundum bricks;(2)the density and the hardness of mullite are lower than those of corundum so the decrease of the corundum content in brick leads to the decrease of the bulk density,the strength and the cold wear resistance;(3)the cross-distributed columnar mullite in the matrix can effectively improve the hot modulus of rupture and the thermal shock resistance of the specimens;(4)considering comprehensively,the andalusite addition shall not exceed 18%.

An Assessment and Identification of Avalanche Hazard Sites in Uri Sector and its Surroundings on Himalayan Mountain

Avalanches are one of the most natural hazard in the mountain areas and therefore, identification of avalanche hazard is necessary for planning future development activities. The study area falls under the international boundary region which generally covered by the snow(38%) on high altitude regions of the western part of Himalayas. Avalanches are triggered in study area during snowfall resulting in loss of human life, property and moreover the transportation and communication affected by the debris which ultimately delays the relief measures. Therefore in this study three major causative parameters i.e terrain, ground cover and meteorological have been incorporated for the identification of avalanche hazard zones(AHZ) by integrating Analytical Hierarchical Process(AHP) method in Geographical Information System(GIS). In the first part of study, avalanche sites have been identified by the criteria related to terrain(slope, aspect and curvature) and ground cover. Weights and ratings to these causative factors and their cumulative effects have been assigned on the basis of experience and knowledge of field. In the second part of the study, single point interpolation and Inverse Distance Weighted(IDW) method has been employed as only one weather station falls in study area. Accordingly, it has been performed to generate the meteorological parameter maps(viz. air temperature and relative humidity) from the field observatories and Automatic Weather Stations(AWS) located at Baaj OP in Uri sector. Finally, the meteorological parameter maps were superimposed on the terrain-based avalanche hazard thematic layers to identify the dynamic avalanche hazard sites. Conventional weighted approach and Analytical Hierarchical Process(AHP) method have been implemented for the identification of AHZ that shows approximately 55% area under maximum hazard zone. Further, the results were validated by overlapping the existing registered avalanche sites. The sites were identified through field survey and avalanche data card followed by its delineation from the toposheet(1:50,000 scale). Interestingly study found that 28% area under moderate and maximum AHZ correlated well with registered avalanche sites when they were overlapped. The accuracy for such works can be increased by field survey under favorable weather condition and by adding data from more number of AWS for predicting avalanche hazards in mountainous regions.

Experimental analysis for the dynamic initiation mechanism of debris flows

Debris flow is one of the major secondary mountain hazards following the earthquake. This study explores the dynamic initiation mechanism of debris flows based on the strength reduction of soils through static and dynamic triaxial tests. A series of static and dynamic triaxial tests were conducted on samples in the lab. The samples were prepared according to different grain size distribution, degree of saturation and earthquake magnitudes. The relations of dynamic shear strength, degree of saturation, and number of cycles are summarized through analyzing experimental results. The findings show that the gravelly soil with a wide and continuous gradation has a critical degree of saturation of approximately 87%, above which debris flows will be triggered by rainfall, while the debris flow will be triggered at a critical degree of saturation of about 73% under the effect of rainfall and earthquake(M>6.5). Debris flow initiation is developed in the humidification process, and the earthquake provides energy for triggering debris flows. Debris flows are more likely to be triggered at the relatively low saturation under dynamic loading than under static loading. The resistance of debris flow triggering relies more on internal frication angle than soil cohesion under the effect of rainfall and earthquake. The conclusions provide an experimental analysis method for dynamic initiation mechanism of debris flows.

Asymptotic Behavior of the Lipschitz-1／2 Modulus of the PL-process for Truncated and Censored Data

In this paper, we give a detailed description of the local behavior of theLipschitz-1/2 modulus for cumulative hazard process and PL-process when the data are subject to lefttruncation and right censored observations. We establish laws of the iterated logarithm of theLipschitz-1/2 modulus of PL-process and cumulative hazard process. These results for the PL-processare sharper than other results found in the literature, which can be used to establish theasymptotic properties of many statistics.

Strong Limit Theorems for Oscillation Moduli of PL-Process and Cumulative Hazard Process under Truncation and Censorship with Applications

In this paper we obtain exact rates of uniform convergence for oscillation moduli and Lipschitz-1/2 moduli of PL-process and cumulative hazard process when the data are subject to left truncation and right censorship. Based on these results, the exact rates of uniform convergence for various types of density and hazard function estimators are derived.

Integrating NLP and Ontology Matching into a Unified System for Automated Information Extraction from Geological Hazard Reports

Many detailed data on past geological hazard events are buried in geological hazard reports and have not been fully utilized. The growing developments in geographic information retrieval and temporal information retrieval offer opportunities to analyse this wealth of data to mine the spatiotemporal evolution of geological disaster occurrence and enhance risk decision making. This study presents a combined NLP and ontology matching information extraction framework for automatically recognizing semantic and spatiotemporal information from geological hazard reports. This framework mainly extracts unstructured information from geological disaster reports through named entity recognition, ontology matching and gazetteer matching to identify and annotate elements, thus enabling users to quickly obtain key information and understand the general content of disaster reports. In addition, we present the final results obtained from the experiments through a reasonable visualization and analyse the visual results. The extraction and retrieval of semantic information related to the dynamics of geohazard events are performed from both natural and human perspectives to provide information on the progress of events.