Natural Hazards and Earth System Science

Results of the ULF electromagnetic emission during earthquake (EQ) swarm and Izu-Miyake volcano eruption at summer period of 2000 are presented and analyzed. Analysis of the obtained data has been performed in 3 main directions: traditional statistical analysis i.e. analysis of time dynamics of spectral density, polarization ratios and their derivatives, principal component analysis and fractal analysis. Statistical characteristics were studied at different frequency sub-bands in a frequency range 10^-3-0.3 Hz. The mentioned methods of data processing are described and obtained results are illustrated and discussed. Some peculiarities of obtained results such as rise of the second principal component and rise of fractal index can be interpreted as a possible short-time precursors

The local when earthquake prediction is based on the connection between geomagnetic quakes and the next incoming minimum or maximum of tidal gravitational potential. The probability time window for the predicted earthquake is for the tidal minimum approximately +/-1 day and for the maximum- +/-2 days. The preliminary statistic estimation on the basis of distribution of the time difference between occurred and predicted earthquakes for the period 2002- 2003 for Sofia region is given. The possibility for creating a local when, where earthquake research and prediction NETWORK is based on the accurate monitoring of the electromagnetic field with special space and time scales under, on and over the Earth surface. The periodically upgraded information from seismic hazard maps and other standard geodetic information as well as other precursory information is essential.

In this paper we study the energy of ULF electromagnetic waves that have been recorded by the satellite DEMETER, during its passing over Haiti before and after a destructive earthquake. This earthquake occurred on 12/1/2010, at geographic Latitude 18.46o and Longitude 287.47o, with Magnitude 7.0 R. Specifically, we are focusing on the variations of energy of Ez-electric field component concerning a time period of 100 days before and 50 days after the strong earthquake. In order to study these variations, we developed a novel method that can be divided in two stages: first we filter the signal keeping only the very low frequencies and afterwards we eliminate its trend using techniques of Singular Spectrum Analysis, combined with a third-degree polynomial filter. As it is shown, a significant increase in energy is observed for the time interval of 30 days before the strong earthquake. This result clearly indicates that the change in the energy of ULF electromagnetic waves could be related to strong precursory earthquake phenomena. Moreover, changes in energy were also observed 25 days after the strong earthquake associated with strong aftershock activity. Finally, we present results concerning the comparison in changes in Energy during night and day passes of the satellite over Haiti, which showed differences in the mean energy values, but similar results as far as the rate of energy change is concerned. Comment: 16 pages, 7 figures, submitted to NHESS

DC electric field in the ionosphere above seismically active regions can be formed in a process of external current insertion into the atmosphere–ionosphere electric circuit. This current arises as a result of convective upward transport of charged aerosols and their gravitational sedimentation. Aerosols are injected into the atmosphere by soil gases intensified in the zones of active faults. In general the horizontal distribution of injected aerosols in such zones is asymmetric. In this report we propose a method for computation of DC electric field generated in the ionosphere and the atmosphere by external electric current with arbitrary spatial distribution. Oblique magnetic field and the conjugate ionosphere effects are taken into consideration.

A phenomenological systems approach for identifying potential precursors in multiple signals of different types for the same local seismically active region is proposed based on the assumption that a large earthquake may be preceded by a system reconfiguration (preparation) at different time and space scales. A nonstationarity factor introduced within the framework of flicker-noise spectroscopy, a statistical physics approach to the analysis of time series, is used as the dimensionless criterion for detecting qualitative (precursory) changes within relatively short time intervals in arbitrary signals. Nonstationarity factors for chlorine-ion concentration variations in the underground water of two boreholes on the Kamchatka peninsula and geacoustic emissions in a deep borehole within the same seismic zone are studied together in the time frame around a large earthquake on October 8, 2001. It is shown that nonstationarity factor spikes (potential precursors) take place in the interval from 70 to 50 days before the earthquake for the hydrogeochemical data and at 29 and 6 days in advance for the geoacoustic data.

This article discusses aspects of communication architecture for early warning systems (EWS) in general and gives details of the specific communication architecture of an early warning system against tsunamis. While its sensors are the "eyes and ears" of a warning system and enable the system to sense physical effects, its communication links and terminals are its "nerves and mouth" which transport measurements and estimates within the system and eventually warnings towards the affected population. Designing the communication architecture of an EWS against tsunamis is particularly challenging. Its sensors are typically very heterogeneous and spread several thousand kilometers apart. They are often located in remote areas and belong to different organizations. Similarly, the geographic spread of the potentially affected population is wide. Moreover, a failure to deliver a warning has fatal consequences. Yet, the communication infrastructure is likely to be affected by the disaster itself. Based on an analysis of the criticality, vulnerability and availability of communication means, we describe the design and implementation of a communication system that employs both terrestrial and satellite communication links. We believe that many of the issues we encountered during our work in the GITEWS project (German Indonesian Tsunami Early Warning System, Rudloff et al., 2009) on the design and implementation communication architecture are also relevant for other types of warning systems. With this article, we intend to share our insights and lessons learned.

This paper describes the examination of three practical tsunami run-up models that can be used to assess the tsunami impact on human beings in densely populated areas. The first of the examined models applies a uniform bottom roughness coefficient throughout the study area. The second uses a very detailed topographic data set that includes the building height information integrated on a Digital Elevation Model (DEM); and the third model utilizes different bottom roughness coefficients, depending on the type of land use and on the percentage of building occupancy on each grid cell. These models were compared with each other by taking the one with the most detailed topographic data (which is the second) as reference. The analysis was performed with the aim of identifying how specific features of high resolution topographic data can influence the tsunami run-up characteristics. Further, we promote a method to be used when very detailed topographic data is unavailable and discuss the related limitations. To this purpose we demonstrate that the effect of buildings on the tsunami flow can be well modeled by using an equivalent roughness coefficient if the topographic data has no information of building height. The results from the models have been utilized to quantify the tsunami impact by using the tsunami casualty algorithm. The models have been applied in Padang city, Indonesia, which is one of the areas with the highest potential of tsunami risk in the world.

Human immediate response is contextualized into different time compartments reflecting the tsunami early warning chain. Based on the different time compartments the available response time and evacuation time is quantified. The latter incorporates accessibility of safe areas determined by a hazard assessment, as well as environmental and demographic impacts on evacuation speed properties assessed using a Cost Distance Weighting GIS approach. Approximately 4.35 million Indonesians live in tsunami endangered areas on the southern coasts of Sumatra, Java and Bali and have between 20 and 150 min to reach a tsunami-safe area. Most endangered areas feature longer estimated-evacuation times and hence the population possesses a weak immediate response capability leaving them more vulnerable to being directly impacted by a tsunami. At a sub-national scale these hotspots were identified and include: the Mentawai islands off the Sumatra coast, various sub-districts on Sumatra and west and east Java. Based on the presented approach a temporal dynamic estimation of casualties and displacements as a function of available response time is obtained for the entire coastal area. As an example, a worst case tsunami scenario for Kuta (Bali) results in casualties of 25 000 with an optimal response time (direct evacuation when receiving a tsunami warning) and 120 000 for minimal response time (no evacuation). The estimated casualties correspond well to observed/reported values and overall model uncertainty is low with a standard error of 5%. The results obtained allow for prioritization of intervention measures such as early warning chain, evacuation and contingency planning, awareness and preparedness strategies down to a sub-district level and can be used in tsunami early warning decision support.

In this paper, an automatic near-real time (NRT) flood detection approach is presented, which combines histogram thresholding and segmentation based classification, specifically oriented to the analysis of single-polarized very high resolution SAR satellite data. The challenge of SAR-based flood detection is addressed in a completely unsupervised way, which assumes no training data and therefore no prior information about the class statistics to be available concerning the area of investigation. This is usually the case in NRT-disaster management, where the collection of ground truth information is not feasible due to time-constraints. A simple thresholding algorithm can be used in the bulk of the cases to distinguish between the classes ‘flood’ and ‘non-flood’ in a high resolution SAR image to detect the largest part of an inundation area. Due to the fact that local gray-level changes may not be distinguished by global thresholding techniques in large satellite scenes the thresholding algorithm is integrated into a split-based approach for the derivation of a global threshold by the analysis and combination of the split inherent information. The derived global threshold is then integrated into a multi-scale segmentation step combining the advantages of small-, medium-and large-scale per parcel segmentation. Experimental investigations performed on a TerraSAR-X Stripmap scene from southwest England during heavy inundations in the year 2007 confirm the effectiveness of the proposed split-based approach in combination with image segmentation and optional integration of digital elevation models.

More than 4 million Indonesians live in tsunami-prone areas along the southern and western coasts of Sumatra, Java and Bali. Although there now exists a Tsunami Early Warning Center in Jakarta, installed after the devastating 2004 tsunami, it is essential to develop tsunami risk knowledge within exposed communities as a basis for tsunami disaster management. Communities need to implement risk reduction strategies to mitigate potential consequences. The major aims of this paper are to present a risk assessment methodology which (1) identifies areas of high tsunami risk in terms of potential loss of life, (2) bridges the gaps between research and practical application, and (3) can be implemented at community level. High risk areas have a high need of action to improve people’s response capabilities towards a disaster and thus to reduce the risk. The methodology developed here is based on a GIS approach and combines hazard probability, hazard intensity, population density and people’s response capability to assess the risk. Within the framework of the GITEWS (German-Indonesian Tsunami Early Warning System) project, the methodology was applied to three pilot areas; one of which is southern Bali. Bali’s tourism is concentrated for a great part in the communities of Kuta, Legian and Seminyak. Here alone, about 20,000 people live in high and very high tsunami risk areas. The development of risk reduction strategies is therefore of significant interest. A risk map produced for the study area in Bali can be used for local planning activities and the development of risk reduction strategies.

We applied canonical transformation to water wave equation not only to remove cubic nonlinear terms but to simplify drastically fourth order terms in Hamiltonian. This transformation explicitly uses the fact of vanishing exact four waves interaction for water gravity waves for 2D potential fluid. After the transformation well-known but cumbersome Zakharov equation is drastically simplified and can be written in X-space in compact way. This new equation is very suitable as for analytic study as for numerical simulation. Localized in space breather-type solution was found. Numerical simulation of collision of two such breathers strongly supports hypothesis of integrability of 2-D free surface hydrodynamics.

This study aims at creating a holistic conceptual approach systematizing the interrelation of (natural) hazards, vulnerability and risk. A general hierarchical risk meta-framework presents potentially affected components of a given system, such as its physical, demographic, social, economic, political or ecological spheres, depending on the particular hazard. Based on this general meta-framework, measurable indicators are specified for the system ‘urban area’ as an example. This framework is used as an outline to identify the capabilities of remote sensing to contribute to the assessment of risk. Various indicators contributing to the outline utilizing diverse remote sensing data and methods are presented. Examples such as built-up density, main infrastructure or population distribution identify the capabilities of remote sensing within the holistic perspective of the framework. It is shown how indexing enables a multilayer analysis of the complex and small-scale urban landscape to take different types of spatial indicators into account to simulate concurrence. The result is an assessment of the spatial distribution of risks within an urban area in the case of an earthquake and its secondary threats, using an inductive method. The results show the principal capabilities of remote sensing to contribute to the identification of physical and demographic aspects of vulnerability, as well as provide indicators for the spatial distribution of natural hazards. Aspects of social, economic or political indicators represent limitations of remote sensing for an assessment complying with the holistic risk framework.

Extreme natural events, like e. g. tsunamis or earthquakes, regularly lead to catastrophes with dramatic consequences. In recent years natural disasters caused hundreds of thousands of deaths, destruction of infrastructure, disruption of economic activity and loss of billions of dollars worth of property and thus revealed considerable deficits hindering their effective management: Needs for stakeholders, decision-makers as well as for persons concerned include systematic risk identification and evaluation, a way to assess countermeasures, awareness raising and decision support systems to be employed before, during and after crisis situations. The overall goal of this study focuses on interdisciplinary integration of various scientific disciplines to contribute to a tsunami early warning information system. In comparison to most studies our focus is on high-end geometric and thematic analysis to meet the requirements of small-scale, heterogeneous and complex coastal urban systems. Data, methods and results from engineering, remote sensing and social sciences are interlinked and provide comprehensive information for disaster risk assessment, management and reduction. In detail, we combine inundation modeling, urban morphology analysis, population assessment, socio-economic analysis of the population and evacuation modeling. The interdisciplinary results eventually lead to recommendations for mitigation strategies in the fields of spatial planning or coping capacity.

Off-shore detection of tsunami waves is a critical component of an effective tsunami early warning system (TEWS). Even more critical is the off-shore detection of local tsunamis, namely tsunamis that strike coastal areas within minutes after generation. In this paper we propose new concepts for near-field tsunami early detection, based on innovative and up-to-date microwave remote sensing techniques. We particularly introduce the NESTRAD (NEar-Space Tsunami RADar) concept, which consists of a real aperture radar accommodated inside a stationary stratospheric airship providing continuous monitoring of tsunamigenic oceanic trenches.

The present paper deals with an attempt to check the theoretical model of self-generated seismo-electromagnetic oscillations of LAI system on the basis of retrospective data. Application of the offered simple model enables one to explain qualitatively the mechanism of VLF electromagnetic emission initiated in the process of an earthquake preparation. Besides, the model enables us to associate telluric character geoelectric and geomagnetic perturbations incited by rock polarization and self-generated electromagnetic oscillations of lithosphere-atmosphere system. L'Aquila earthquake taken as an example to isolate reliably the Earth VLF emission from the magnetospheric electromagnetic emission of the same frequency range, MHD criterion is offered together with geomagnetic activity indexes. On the basis of the considered three earthquakes, according to the opinion of authors the model of self-generated seismo-electromagnetic oscillations of the LAI system will enable us to approach the problem of resolution of earthquake prediction with certain accuracy.

An innovative newly developed modular and standards based Decision Support System (DSS) is presented which forms part of the German Indonesian Tsunami Early Warning System (GITEWS). The GITEWS project stems from the effort to implement an effective and efficient Tsunami Early Warning and Mitigation System for the coast of Indonesia facing the Sunda Arc along the islands of Sumatra, Java and Bali. The geological setting along an active continental margin which is very close to densely populated areas is a particularly difficult one to cope with, because potential tsunamis' travel times are thus inherently short. National policies require an initial warning to be issued within the first five minutes after an earthquake has occurred. There is an urgent requirement for an end-to-end solution where the decision support takes the entire warning chain into account. The system of choice is based on pre-computed scenario simulations and rule-based decision support which is delivered to the decision maker through a sophisticated graphical user interface (GUI) using information fusion and fast information aggregation to create situational awareness in the shortest time possible. The system also contains risk and vulnerability information which was designed with the far end of the warning chain in mind – it enables the decision maker to base his acceptance (or refusal) of the supported decision also on regionally differentiated risk and vulnerability information (see Strunz et al., 2010). While the system strives to provide a warning as quickly as possible, it is not in its proper responsibility to send and disseminate the warning to the recipients. The DSS only broadcasts its messages to a dissemination system (and possibly any other dissemination system) which is operated under the responsibility of BMKG – the meteorological, climatological and geophysical service of Indonesia – which also hosts the tsunami early warning center. The system is to be seen as one step towards the development of a "system of systems" enabling all countries around the Indian Ocean to have such early warning systems in place. It is within the responsibility of the UNESCO Intergovernmental Oceonographic Commission (IOC) and in particular its Intergovernmental Coordinating Group (ICG) to coordinate and give recommendations for such a development. Therefore the Decision Support System presented here is designed to be modular, extensible and interoperable (Raape et al., 2010).

The new field of complex systems supports the view that a number of systems arising from disciplines as diverse as physics, biology, engineering, and economics may have certain quantitative features that are intriguingly similar. The earth is a living planet where many complex systems run perfectly without stopping at all. The earthquake generation is a fundamental sign that the earth is a living planet. Recently, analyses have shown that human-brain-type disease appears during the earthquake generation process. Herein, we show that human-heart-type disease appears during the earthquake preparation of the earthquake process. The investigation is mainly attempted by means of critical phenomena, which have been proposed as the likely paradigm to explain the origins of both heart electric fluctuations and fracture induced electromagnetic fluctuations. We show that a time window of the damage evolution within the heterogeneous Earth's crust and the healthy heart's electrical action present the characteristic features of the critical point of a thermal second order phase transition. A dramatic breakdown of critical characteristics appears in the tail of the fracture process of heterogeneous system and the injury heart's electrical action. Analyses by means of Hurst exponent and wavelet decomposition further support the hypothesis that a dynamical analogy exists between the geological and biological systems under study.

In this paper we show, in terms of Fisher information and approximate entropy, that the two strong impulsive kHz electromagnetic (EM) bursts recorder prior to the Athens EQ (7 September 1999, magnitude 5.9) present compatibility to the radar interferometry data and the seismic data analysis, which indicate that two fault segments were activated during Athens EQ. The calculated Fisher information and approximate entropy content ratios closely follow the radar interferometry result that the main fault segment was responsible for 80% of the total energy released, while the secondary fault segment for the remaining 20%. This experimental finding, which appears for the first time in the literature, further enhances the hypothesis for the seismogenic origin of the analyzed kHz EM bursts.

Self-similarity may stem from two origins: the process' increments infinite variance and/or process' memory. The $b$-value of the Gutenberg-Richter law comes from the first origin. In the frame of natural time analysis of earthquake data, a fall of the b-value observed before large earthquakes reflects an increase of the order parameter fluctuations upon approaching the critical point (mainshock). The increase of these fluctuations, however, is also influenced from the second origin of self-similarity, i.e., temporal correlations between earthquake magnitudes. This is supported by observations and simulations of an earthquake model.

It has been suggested that fracture-induced MHz-kHz electromagnetic (EM) emissions, which emerge from a few days up to a few hours before the main seismic shock occurrence permit a real-time monitoring of the damage process during the last stages of earthquake preparation, as it happens at the laboratory scale. Despite fairly abundant evidence, EM precursors have not been adequately accepted as credible physical phenomena. These negative views are enhanced by the fact that certain 'puzzling features' are repetitively observed in candidate fracture-induced pre-seismic EM emissions. More precisely, EM silence in all frequency bands appears before the main seismic shock occurrence, as well as during the aftershock period. Actually, the view that 'acceptance of 'precursive' EM signals without convincing co-seismic signals should not be expected' seems to be reasonable. In this work we focus on this point. We examine whether the aforementioned features of EM silence are really puzzling ones or, instead, reflect well-documented characteristic features of the fracture process, in terms of: universal structural patterns of the fracture process, recent laboratory experiments, numerical and theoretical studies of fracture dynamics, critical phenomena, percolation theory, and micromechanics of granular materials. Our analysis shows that these features should not be considered puzzling.

Due to the catastrophic consequences of tsunamis, early warnings need to be issued quickly in order to mitigate the hazard. Additionally, there is a need to represent the uncertainty in the predictions of tsunami characteristics corresponding to the uncertain trigger features (e.g. either position, shape and speed of a landslide, or sea floor deformation associated with an earthquake). Unfortunately, computer models are expensive to run. This leads to significant delays in predictions and makes the uncertainty quantification impractical. Statistical emulators run almost instantaneously and may represent well the outputs of the computer model. In this paper, we use the Outer Product Emulator to build a fast statistical surrogate of a landslide-generated tsunami computer model. This Bayesian framework enables us to build the emulator by combining prior knowledge of the computer model properties with a few carefully chosen model evaluations. The good performance of the emulator is validated using the Leave-One-Out method.

Many geo-hazards such as earthquakes, tsunamis, volcanic eruptions, severe weather, etc., produce acoustic waves with sub-audible frequency, so called infrasound. This sound propagates from the surface to the middle and upper atmosphere causing pressure and temperature perturbations. Temperature fluctuations connected with the above mentioned events usually are very weak at the surface, but the amplitude increases with height because of the exponential decrease of atmospheric pressure with increasing altitude. At the mesopause region (80–100 km height) signal amplitudes are about two to three orders of magnitude larger than on the ground. The GRIPS (GRound-based Infrared P-branch Spectrometer) measurement system operated by the German Remote Sensing Data Center of the German Aerospace Center (DLR-DFD) derives temperatures of the mesopause region by observing hydroxyl (OH) airglow emissions in the near infrared atmospheric emission spectrum originating from a thin layer at approximately 87 km height. The GRIPS instrument is in principle suited for the detection of infrasonic signals generated by e.g. tsunamis and other geo-hazards. This is due to the fact that the infrasound caused by such events should induce observable short-period fluctuations in the OH airglow temperatures. First results obtained during a field campaign performed at the Environmental Research Station "Schneefernerhaus", Zugspitze (47.4° N, 11.0° E) from October to December 2008 are presented regarding potential sources of meteorological and orographical origin. An adequate distinction of the overlapping infrasonic signatures caused by different infrasound sources in the OH temperature record is needed for the ascription to the proper source. The approach presented here could form a contribution to a hazard monitoring and early warning system.

Shear wave velocities have a fundamental role in connection with the mitigation of seismic hazards, as their low values are the main causes of site amplification phenomena and can significantly influence the susceptibility of a territory to seismic-induced landslides. The shear wave velocity (Vs) and modulus (G) of each lithological unit are influenced by factors such as the degree of fracturing and faulting, the porosity, the clay amount and the precipitation, with the latter two influencing the unit water content. In this paper we discuss how these factors can affect the Vs values and report the results of different analyses that quantify the reduction in the rock Vs and shear modulus values connected to the presence of clay and water. We also show that significant results in assessing seismic-induced slope failure susceptibility for land planning targets could be achieved through a careful evaluation, based only on literature studies, of the geo-lithological and geo-seismic features of the study area.

The need for protection against rockfall has led to the development of different types of technological solutions that are able to both prevent blocks from detaching from rock walls and to control, intercept or deviate the blocks during movement. Of the many devices that are able to intercept and stop a block, one of the most frequently used is net fence. Many different types of full-scale tests have been carried out, with different test site geometries and procedures to study their behaviour and to certify these devices. This has led to a series of data and information that are not easy to compare. The recent endorsement, by the European Organization for Technical Approvals (EOTA), of a European Technical Approval Guideline (ETAG), which defines how to test and assess the performance of a net fence, is therefore a great innovation that will change both the market and the design procedures of these devices. The most important innovations introduced by this new guideline are here presented and discussed and a net fence design procedure for protection against rockfall is provided.

The British coast is not considered at particular risk from tsunami, a view that is supported by a number of recent government reports. However, these reports largely ignore some written historic records that suggest southern Britain has experienced a number of events over the past 1000 yrs. This study briefly assesses these records and recognises four groups of events: 1) sea disturbance and coastal floods in southeast England linked to earthquakes in the Dover Straits (e.g. 1382 and 1580), 2) far-field tsunami reaching the coast of the British Isles, for example, from earthquakes along the Azores-Gibraltar Fault Zone offshore Portugal (e.g. 1755), 3) tsunami associated with near-coastal low magnitude earthquakes (e.g. 1884 and 1892), and 4) a flood event in AD 1014 that has been linked to comet debris impact. The seismogenic events range from minor water disturbance, through seismic seiching, to small and "giant" waves, suggesting near-coastal, low-magnitude, shallow earthquakes may be capable of triggering disturbance in relatively shallow water, as supported by similar occurrences elsewhere, and that the British tsunami risk requires a more careful evaluation.