ALBERT

Description: Kinematics of a mass movement constrained by sparse and inhomogeneous data Natural Hazards and Earth System Science, 11, 1609-1618, 2011 Author(s): M. Karbon, E. Brückl, E. Hegedüs, and A. Preh On 12 February 2008, a landslide occurred along a 50 m high bank of the Danube river near Dunaszekcsö, Hungary. The initial state is only incompletely documented and the geodetic data acquired after the mass movement are sparse. A generalized 3-D topographic model of the landslide and its surrounding area was assembled and a representative longitudinal profile extracted. The reconstruction of the original surface is based on an orthophoto as well as on morphological considerations. Recorded observations include the locations of the outcrops of basal sliding surfaces, displacements at the main scarp and in the lower part of the slide, and a value to describe the total mass transport. Such sparse and inhomogeneous data were insufficient to derive a comprehensive documentation of the landslide or obtain adequate constraints for an accurate numerical analysis. Therefore, slider block models were fitted to the field data, which have only a small number of free parameters. A general view on the morphology of the mass movement justifies its classification as a rotational slide. A double slider block model fits all observational parameters within their error margin and supplies valuable information on the geometry of the slide. Estimates of the residual friction angles were derived and the question of reactivation was addressed. Finite Difference (FD) modelling and the application of conventional stability analysis support the geometry of the slider blocks and the computed average residual friction angles. Generally, the results are assumed to represent preliminary information, which could only be attained by the combination of the thinly distributed geodetic data with qualitative morphological observations and the implementation of a model. This type of information can be gained quickly and may be valuable for preliminary hazard mitigation measures or the planning of a comprehensive exploration and monitoring program.

Description: Looking for evidence of climate change impacts in the eastern Irish Sea Natural Hazards and Earth System Science, 11, 1641-1656, 2011 Author(s): L. S. Esteves, J. J. Williams, and J. M. Brown Although storminess is often cited as a driver of long-term coastal erosion, a lack of suitable datasets has only allowed objective assessment of this claim in a handful of case studies. This reduces our ability to understand and predict how the coastline may respond to an increase in "storminess" as suggested by global and regional climate models. With focus on 16 km of the Sefton coastline bordering the eastern Irish Sea (UK), this paper analyses available measured datasets of water level, surge level, wave height, wind speed and barometric pressure with the objective of finding trends in metocean climate that are consistent with predictions. The paper then examines rates of change in shoreline position over the period 1894 to 2005 with the aim of establishing relationships with climatic variability using a range of measured and modelled metocean parameters (with time spans varying from two to eight decades). With the exception of the mean monthly wind speed, available metocean data do not indicate any statistically significant changes outside seasonal and decadal cycles. No clear relationship was found between changes in metocean conditions and rates of shoreline change along the Sefton coast. High interannual variability and the lack of long-term measurements make unambiguous correlations between climate change and shoreline evolution problematic. However, comparison between the North Atlantic Oscillation winter index (NAOw) and coastline changes suggest increased erosion at times of decreasing NAOw values and reduced erosion at times of increasing NAOw values. Erosion tends to be more pronounced when decreasing NAOw values lead to a strong negative NAO phase. At present, anthropogenic changes in the local sediment budget and the short-term impact of extreme events are still the largest threat likely to affect coastal flooding and erosion risk in the short- and medium-term. Nevertheless, the potential impacts of climate change in the long-term should not be ignored.

Description: Comparing historical-hydrogeomorphological reconstitution and hydrological-hydraulic modelling in the estimation of flood-prone areas – a case study in Central Portugal Natural Hazards and Earth System Science, 11, 1669-1681, 2011 Author(s): P. P. Santos, A. O. Tavares, and A. I. A. S. S. Andrade The Arunca River basin in Central Portugal has a historical record of hazardous events related to floods, causing widespread disturbance. This article describes the application of two approaches based on well-known methods for the estimation of flood-prone areas: (i) historical-hydrogeomorphological reconstitution, applied to the entire Arunca River basin, and (ii) hydrological-hydraulic modelling, applied to four sections selected from different (upper, middle and lower) sectors of the basin and including urban and rural areas along the Arunca River. The mapping of the flood-prone areas obtained by these two methods was compared in order to identify the main differences and similarities. Human interventions (river channel and floodplain morphological changes) were found to be the main factor explaining the differences and similarities between the results obtained by both methods. The application of hydrological-hydraulic modelling proved important in reinforcing the results of the historical-hydrogeomorphological method; it also helped in complementing the results produced by the latter method in urban areas and in areas with insufficient historical records. The application of the historical-hydrogeomorphological method, in turn, allowed for the size of the flood-prone areas to be determined where the primary data (e.g. geometry, roughness and flow) was not accurate enough for hydrological-hydraulic modelling. The methodological approach adopted demonstrates the strong complementary relationship between the different existing methods for estimating flood-prone areas, and may be reproduced for other drainage basins.

Description: The contribution of engineering surveys by means of GPS to the determination of crustal movements in Istanbul Natural Hazards and Earth System Science, 11, 1705-1713, 2011 Author(s): M. Özyaşar and M. T. Özlüdemir Global Navigation Satellite Systems (GNSS) are space based positioning techniques and widely used in geodetic applications. Geodetic networking accomplished by engineering surveys constitutes one of these tasks. Geodetic networks are used as the base of all kinds of geodetic implementations, Co from the cadastral plans to the relevant surveying processes during the realization of engineering applications. Geodetic networks consist of control points positioned in a defined reference frame. In fact, such positional information could be useful for other studies as well. One of such fields is geodynamic studies that use the changes of positions of control stations within a network in a certain time period to understand the characteristics of tectonic movements. In Turkey, which is located in tectonically active zones and struck by major earthquakes quite frequently, the positional information obtained in engineering surveys could be very useful for earthquake related studies. For this purpose, a GPS (Global Positioning System) network of 650 stations distributed over Istanbul (Istanbul GPS Triangulation Network; abbreviated IGNA) covering the northern part of the North Anatolian Fault Zone (NAFZ) was established in 1997 and measured in 1999. From 1998 to 2004, the IGNA network was extended to 1888 stations covering an area of about 6000 km 2 , the whole administration area of Istanbul. All 1888 stations within the IGNA network were remeasured in 2005. In these two campaigns there existed 452 common points, and between these two campaigns two major earthquakes took place, on 17 August and 12 November 1999 with a Richter scale magnitude of 7.4 and 7.2, respectively. Several studies conducted for estimating the horizontal and vertical displacements as a result of these earthquakes on NAFZ are discussed in this paper. In geodynamic projects carried out before the earthquakes in 1999, an annual average velocity of 2–2.5 cm for the stations along the NAFZ were estimated. Studies carried out using GPS observations in the same area after these earthquakes indicated that point displacements vary depending on their distance to the epicentres of the earthquakes. But the directions of point displacements are similar. The results obtained through the analysis of the IGNA network also show that there is a common trend in the directions of point displacements in the study area. In this paper, the past studies about the tectonics of Marmara region are summarised and the results of the displacement analysis on the IGNA network are discussed.

Description: Quantitative estimation of landslide risk from rapid debris slides on natural slopes in the Nilgiri hills, India Natural Hazards and Earth System Science, 11, 1723-1743, 2011 Author(s): P. Jaiswal, C. J. van Westen, and V. Jetten A quantitative procedure for estimating landslide risk to life and property is presented and applied in a mountainous area in the Nilgiri hills of southern India. Risk is estimated for elements at risk located in both initiation zones and run-out paths of potential landslides. Loss of life is expressed as individual risk and as societal risk using F-N curves, whereas the direct loss of properties is expressed in monetary terms. An inventory of 1084 landslides was prepared from historical records available for the period between 1987 and 2009. A substantially complete inventory was obtained for landslides on cut slopes (1042 landslides), while for natural slopes information on only 42 landslides was available. Most landslides were shallow translational debris slides and debris flowslides triggered by rainfall. On natural slopes most landslides occurred as first-time failures. For landslide hazard assessment the following information was derived: (1) landslides on natural slopes grouped into three landslide magnitude classes, based on landslide volumes, (2) the number of future landslides on natural slopes, obtained by establishing a relationship between the number of landslides on natural slopes and cut slopes for different return periods using a Gumbel distribution model, (3) landslide susceptible zones, obtained using a logistic regression model, and (4) distribution of landslides in the susceptible zones, obtained from the model fitting performance (success rate curve). The run-out distance of landslides was assessed empirically using landslide volumes, and the vulnerability of elements at risk was subjectively assessed based on limited historic incidents. Direct specific risk was estimated individually for tea/coffee and horticulture plantations, transport infrastructures, buildings, and people both in initiation and run-out areas. Risks were calculated by considering the minimum, average, and maximum landslide volumes in each magnitude class and the corresponding minimum, average, and maximum run-out distances and vulnerability values, thus obtaining a range of risk values per return period. The results indicate that the total annual minimum, average, and maximum losses are about US$ 44 000, US$ 136 000 and US$ 268 000, respectively. The maximum risk to population varies from 2.1 × 10 −1 for one or more lives lost to 6.0 × 10 −2 yr −1 for 100 or more lives lost. The obtained results will provide a basis for planning risk reduction strategies in the Nilgiri area.

Description: Trends in climatic variables and future reference evapotranspiration in Duero Valley (Spain) Natural Hazards and Earth System Science, 11, 1795-1805, 2011 Author(s): R. Moratiel, R. L. Snyder, J. M. Durán, and A. M. Tarquis The impact of climate change and its relation with evapotranspiration was evaluated in the Duero River Basin (Spain). The study shows possible future situations 50 yr from now from the reference evapotranspiration (ET o ). The maximum temperature ( T max ), minimum temperature ( T min ), dew point ( T d ), wind speed ( U ) and net radiation ( R n ) trends during the 1980–2009 period were obtained and extrapolated with the FAO-56 Penman-Montheith equation to estimate ET o . Changes in stomatal resistance in response to increases in CO 2 were also considered. Four scenarios were done, taking the concentration of CO 2 and the period analyzed (annual or monthly) into consideration. The scenarios studied showed the changes in ET o as a consequence of the annual and monthly trends in the variables T max , T min , T d , U and R n with current and future CO 2 concentrations (372 ppm and 550 ppm). The future ET o showed increases between 118 mm (11 %) and 55 mm (5 %) with respect to the current situation of the river basin at 1042 mm. The months most affected by climate change are May, June, July, August and September, which also coincide with the maximum water needs of the basin's crops.

Description: Possible interrelation between the lead time of precursory seismic electric signals (SES) and geodynamics in Aegean Sea Natural Hazards and Earth System Science, 11, 1599-1603, 2011 Author(s): E. Dologlou The seismicity of the last 15 years in the Aegean Sea revealed that earthquakes ( M w 〉 5) with epicentres falling within the Sporades basin and the confined area north of Samos island were preceded by electric seismic signals (SES) with a remarkably long lead time. A possible explanation of this behaviour by means of specific tectonics and geodynamics which characterise these two regions, such as a significant small crustal thickness and a high heat flow rate, has been attempted. New data seem to strengthen the above hypothesis.

Description: Daytime variations of foE connected to earthquakes Natural Hazards and Earth System Science, 11, 1807-1812, 2011 Author(s): E. V. Liperovskaya, V. V. Bogdanov, P.-F. Biagi, C.-V. Meister, and V. A. Liperovsky In the present work it is shown that, in accordance with the observations of the vertical sounding station "Tashkent", the critical foE-frequency of the daytime E-layer increases about one day before winter-earthquakes with magnitudes M 〉 5 and depths of the epicentre of h 〈 60 km, which appeared at distances of R 〈 2000 km from the station. The reliability of the result is larger than 99 %. The phenomenon is not observed for summer-earthquakes. It seems to be determined by the atmospheric wind system. Further, the variations of the foE-frequency are compared with possible simultaneous variations of the critical frequency foF2 of the F2-layer. First results show that only very large changes of the ionisation density in the E-layer influence the ionisation density in the F-region. Therefore, no synchronous growth of the foE- and foF2-frequencies 1–2 days before seismic shocks could be observed.

Description: Shallow circulation groundwater – the main type of water containing hazardous radon concentration Natural Hazards and Earth System Science, 11, 1695-1703, 2011 Author(s): T. A. Przylibski The main factors affecting the value of 222 Rn activity concentration in groundwater are the emanation coefficient of reservoir rocks ( K em ), the content of parent 226 Ra in these rocks ( q ), changes in the volume and flow velocity as well as the mixing of various groundwater components in the circulation system. The highest values of 222 Rn activity concentration are recorded in groundwaters flowing towards an intake through strongly cracked reservoir rocks undergoing weathering processes. Because of these facts, waters with hazardous radon concentration levels, i.e. containing more than 100 Bq dm −3 222 Rn, could be characterised in the way that follows. They are classified as radon waters, high-radon waters and extreme-radon waters. They belong to shallow circulation systems (at less than a few dozen metres below ground level) and are contemporary infiltration waters, i.e. their underground flow time ranges from several fortnights to a few decades. Because of this, these are usually poorly mineralised waters (often below 0.2–0.5 g dm −3 ). Their resources are renewable, but also vulnerable to contamination. Waters of this type are usually drawn from private intakes, supplying water to one or at most a few households. Due to an increased risk of developing lung tumours, radon should be removed from such waters when still in the intake. To achieve this aim, appropriate legislation should be introduced in many countries.

Description: Precipitation change in Southern Italy linked to global scale oscillation indexes Natural Hazards and Earth System Science, 11, 1683-1694, 2011 Author(s): T. Caloiero, R. Coscarelli, E. Ferrari, and M. Mancini This study investigates precipitation variability in five regions of Southern Italy (Campania, Apulia, Basilicata, Calabria and Sicily) using a homogeneous database of about 70 rain gauges with more than 50 years of observation. First, a statistical analysis was performed through the Mann-Kendall non-parametric test in order to determine rainfall the trend on both yearly and seasonal scales. Then, the relationship between the rainfall and some teleconnection pattern indexes was investigated using Spearman's test. The results show remarkable statistically significant negative trends for annual and winter aggregations in most part of the series. Moreover, a strong correlation has emerged between the teleconnection patterns and precipitation in Southern Italy, particularly in winter and on the Tyrrhenian side of the study area.