A Nonextensive Statistical Physics Analysis of the 1995 Kobe, Japan Earthquake

This paper presents an analysis of the distribution of earthquake magnitudes for the period 1990–1998 in a broad area surrounding the epicenter of the 1995 Kobe earthquake. The frequency–magnitude distribution analysis is performed in a nonextensive statistical physics context. The nonextensive parameter q M , which is related to the frequency-magnitude distribution, reflects the existence of long-range correlations and is used as an index of the physical state of the studied area. Examination of the possible variations of q M values is performed during the period 1990–1998. A significant increase of q M occurs some months before the strong earthquake on April 9, 1994 indicating the start of a preparation phase prior to the Kobe earthquake. It should be noted that this increase coincides with the occurrence of six seismic events. Each of these events had a magnitude M = 4.1. The evolution of seismicity along with the increase of q M indicate the system’s transition away from equilibrium and its preparation for energy release. It seems that the variations of q M values reflect rather well the physical evolution towards the 1995 Kobe earthquake

Hazard criteria for wake vortex encounters

A piloted, motion-base simulation was conducted to evaluate the ability of simulators to produce realistic vortex encounters and to develop criteria to define hazardous encounters. Evaluation of the simulation by pilots experienced in vortex encounters confirmed the capability of the simulator to realistically reproduce wake vortex encounters. A boundary for encounter hazard based on subjective pilot opinion was identified in terms of maximum bank angle. For encounter altitudes from 200 to 500 ft (61.0 to 152.4 m), tentative hazard criteria established for visual flight conditions indicated that the acceptable upset magnitude increased nearly linearly with increasing altitude. The data suggest that the allowable upsets under instrument conditions no greater than 50 percent of that allowable under visual conditions

Wake vortex encounter hazards criteria for two aircraft classes

An investigation was conducted using a piloted, motion-base simulator to determine wake vortex hazard criteria for two classes of jet transport aircraft. A light business jet and a large multiengine jet transport were represented respectively. The hazard boundaries were determined in terms of the maximum bank angle due to the vortex encounter. Upsets as small as 7 deg in bank angle were considered to be hazardous at breakout altitude (200 ft (61.0 m)) for Instrument Flight Rule (IFR) and at 50 ft (15.2 m) for Visual Flight Rule (VFR) for both aircraft classes. Proximity to the ground was the primary reason for a hazardous rating. This was reflected in the reduction in the maximum bank angle at the hazard boundary and in more consistent ratings as altitude was decreased

Dynamic Multifractality in Earthquake Time Series: Insights from the Corinth Rift, Greece

Earthquake time series are widely used to characterize the main features of seismicity and to provide useful insights into the dynamics of the seismogenic system. Properties such as intermittency and non-stationary clustering are common in earthquake time series such that multifractal concepts seem essential to describe the temporal clustering variability. Here we use a multifractal approach to study the time dynamics of the recent earthquake activity in the Corinth rift. The results indicate the degree of heterogeneous clustering and correlations acting at all time scales that suggest non-Poissonian behavior. Additionally, the multifractal analysis in different time periods showed that the degree of multifractality exhibits strong variations with time, which are associated with the dynamic evolution of the earthquake activity in the rift and the transition between periods of high and low seismicity

Movement analysis to indicate discomfort in vehicle seats

Long distance travel is associated with discomfort and fatigue. It is a significant challenge to design a seat that remains comfortable for the occupant over the several hours required for many long-distance journeys. When designing seats, an indication of the perception of comfort/discomfort can be useful either for research and development purposes or potentially for automated systems to take actions that might mitigate discomfort. This paper considered a system that uses measurements of body movement in a seat to provide an objective measure of perceptions of discomfort. The system uses cameras and image processing to recognize when a seat occupant makes a movement in the seat which could be associated with relief of discomfort. The system was validated using a laboratory driving simulator. 10 participants volunteered to complete a study in which they drove for 90 minutes and gave subjective ratings of discomfort every 10 minutes, whilst also being observed using the camera system. It was shown that using a simple algorithm an association could be made between the movements of the driver and subjective ratings of discomfort. However, there remain challenges to improve reliability, optimize movement detection thresholds, and to make it more robust to naturalistic driving scenarios

The 2016 Kumamoto Earthquakes: Cascading Geological Hazards and Compounding Risks

A sequence of two strike-slip earthquakes occurred on April 14 and 16, 2016 in the intraplate region of Kyushu Island, Japan, apart from subduction zones, and caused significant damage and disruption to the Kumamoto region. The analyses of regional seismic catalog and available strong motion recordings reveal striking characteristics of the events, such as migrating seismicity, earthquake surface rupture, and major foreshock-mainshock earthquake sequences. To gain valuable lessons from the events, a UK Earthquake Engineering Field Investigation Team (EEFIT) was dispatched to Kumamoto, and earthquake damage surveys were conducted to relate observed earthquake characteristics to building and infrastructure damage caused by the earthquakes. The lessons learnt from the reconnaissance mission have important implications on current seismic design practice regarding the required seismic resistance of structures under multiple shocks and the seismic design of infrastructure subject to large ground deformation. The observations also highlight the consequences of cascading geological hazards on community resilience. To share the gathered damage data widely, geo-tagged photos are organized using Google Earth and the kmz file is made publicly available.The work is funded by the EPSRC grant (EP/I01778X/1) for the Earthquake Engineering Field Investigation Team (EEFIT). The financial supports for industrial members (GC, LH, LK, and RM) are provided by Arup, Mott MacDonald, and Willis

Indigenous Mountain People’s Risk Perception to Environmental Hazards in Border Conflict Areas

This study aims to understand community risk perception to environmental hazards in a border conflict zone context in high-mountain areas. Participatory rural appraisal (PRA) tools were applied by the social science team. The results were validated with a hazard map prepared by a separate team comprised of geologists. Turtuk, the northernmost village in Ladakh, India located near the line of control with Pakistan was undertaken as a case study. Turtuk represents a high mountain indigenous rural community which has experienced several major disasters (flash flooding and landslides in 2010, 2014, and 2015) and territorial conflicts (wars in 1971 and 1999 with Pakistan) in recent times. The villagers were able to identify various environmental hazards and associated risk zones through participatory timeline, hazard and dream mapping exercises. The PRA maps matched the geological hazard map of Turtuk, demonstrating that community people are highly aware of surrounding hazards regardless of differences in age, sex, education, occupation, and religion. They apply indigenous knowledge to deal with the adverse climate and calamities. The technique, of analysing community vulnerability in the context of conflict and disasters by applying qualitative PRA tools and validating the mapping results, as piloted in this study is novel and replicable in similar settings

Lessons Learnt From the 2009 Padang Indonesia, 2011 Tōhoku Japan and 2016 Muisne Ecuador Earthquakes

This paper presents the observations during the UK Earthquake Engineering Field Investigation Team (EEFIT)'s post-earthquake reconnaissance missions to the September 20, 2009 Padang (Mw7.6), March 11, 2011 Tōhoku (Mw9.0) and April 16, 2016 Muisne (Mw7.8) earthquakes. The performance of buildings and geotechnical structures within the affected regions were investigated to gain insights on their design and construction deficiencies. Findings on these damages observed are compared along with the characteristics of the earthquake and nature of building codes in these countries. They include building damages attributed to a combination of structural resonance, deficiencies in reinforcement detailing, vulnerability to soft story collapse, ground settlement, soil liquefaction, and landslides. It was demonstrated that buildings which were severely damaged had natural building frequencies coinciding with the dominant frequencies of the ground shaking. The locations of damage of several such buildings showed insufficient confining reinforcements and lapping of stirrup links. Soft story collapses were also observed in the three earthquakes, although many were attributed to old building codes that were less effective. In areas affected by the Muisne earthquake, soft story collapses were mainly found at mid height of the building rather than at the ground floor as observed in the Padang and Tōhoku earthquakes, likely due to extension of building long after the bottom floors were completed. Such extension of building can either lead to local reduction in capacity due to weaker concrete-rebar bonding, possibly insufficient lapping of reinforcement, as well as increased axial loads. In the aspect of geotechnical failure, foundations of buildings found on piles performed reasonably well, except for areas affected by soil liquefaction. Landslides occurred following these earthquakes led to large concentration of casualties and property losses, motivating the EEFIT teams to invest efforts in hazard mapping and ground-truthing exercises using satellite images at Padang and Muisne earthquakes respectively. Such geospatial tools applied in these three earthquakes were reviewed and demonstrated to be capable of identifying landslide sites and producing reliable landslide hazard map

Time-dependent brittle creep in Darley Dale sandstone

The characterization of time-dependent brittle rock deformation is fundamental to understanding the long-term evolution and dynamics of the Earth's crust. The chemical influence of pore water promotes time-dependent deformation through stress corrosion cracking that allows rocks to deform at stresses far below their short-term failure strength. Here, we report results from a study of time-dependent brittle creep in water-saturated samples of Darley Dale sandstone (initial porosity, 13%) under triaxial stress conditions. Results from conventional creep experiments show that axial strain rate is heavily dependent on the applied differential stress. A reduction of only 10% in differential stress results in a decrease in strain rate of more than two orders of magnitude. However, natural sample variability means that multiple experiments must be performed to yield consistent results. Hence we also demonstrate that the use of stress-stepping creep experiments can successfully overcome this issue. We have used the stress-stepping technique to investigate the influence of confining pressure at effective confining pressures of 10, 30, and 50 MPa (while maintaining a constant 20 MPa pore fluid pressure). Our results demonstrate that the stress corrosion process appears to be significantly inhibited at higher effective pressures, with the creep strain rate reduced by multiple orders of magnitude. The influence of doubling the pore fluid pressure, however, while maintaining a constant effective confining pressure, is shown to influence the rate of stress corrosion within the range expected from sample variability. We discuss these results in the context of microstructural analysis, acoustic emission hypocenter locations, and fits to proposed macroscopic creep laws