Mean Recurrence Interval Research Articles

Estimation of Hurricane Wind Speed Probabilities: Application to New York City and Other Coastal Locations

AbstractA procedure is presented for estimating parametric probabilistic models of hurricane wind speeds from existing information on state-of-the-art estimates of wind speeds with various mean recurrence intervals (MRIs). Such models may be needed, for example, for the estimation of hurricane wind speeds with long MRIs required for the performance-based design of structures susceptible of experiencing nonlinear behavior. First, the procedure is applied to the case where that information is obtained from ASCE 7-10 wind maps, and examples are provided of its application to a number of coastal mileposts on the Gulf and Atlantic coasts. Next, the procedure is applied by using, in addition to the ASCE 7-10 information, hurricane wind speeds with 1,000,000- and 10,000,000-year MRIs estimated in a 2011 Nuclear Regulatory Commission (NRC) report. It is then argued that ASCE 7-10 Standard basic wind speeds for New York City are not conservative with respect to their counterparts specified in the standard for othe...

Revision of urban drainage design rules after assessment of climate change impacts on precipitation extremes at Uccle, Belgium

Design parameters for urban drainage systems in Belgium have been revised. The revision involves extrapolation of the design rainfall statistics, taking into account the current knowledge on future climate change trends till 2100. Uncertainties in these trend projections have been assessed after statistically analysing and downscaling a broad ensemble set of 44 regional and 69 global climate model runs. Climate change scenarios were developed, tailored for the application of urban drainage impact analysis. By means of a further advanced quantile perturbation method, a 100-year 10-min historical rainfall series was perturbed for each climate change scenario. The perturbations were based on the empirical frequency distributions for the lower return periods, and calibrated extreme value distributions for the higher return periods. Based on the climate scenarios and perturbed historical rainfall series, changes in intensity–duration–frequency (IDF) statistics and design storms have been derived. It was shown that the 10-year design storm intensity can increase up to about 50% by the end of this century. Or, systems currently designed for a 20-year return period of flooding, might flood with a mean recurrence interval of – in order of magnitude – 5 years by the end of the century. Based on a continuous reservoir simulation approach, changes in overflow frequency of storage facilities have been quantified for a wide range of storage capacities and infiltration/throughflow rates. It is found that increase in storage capacity of 11–51% is required to keep the overflow frequency to the current level.

Assessing small failure probability by importance splitting method and its application to wind turbine extreme response prediction

This study presents an effective simulation framework with importance splitting (ISp) method for estimating small failure probabilities of dynamic structures with multi-correlated stochastic excitations, and addresses its application to predictions of large wind turbine extreme responses. The ISp method, also referred to as subset simulation with splitting, splits important sample paths into multiple branches at various stages in the simulation. It permits the estimation of a small failure probability of a rare event through estimations of conditional probabilities of intermediate subset events. The framework presented in this study combines the ISp method with multivariate autoregressive (MAR) modeling of stochastic excitations. The MAR model of excitations is established based on their cross power spectral density matrix, which transfers the stochastic excitations as the output of a loading system with a vector-valued uncorrelated white noise process as input. This scheme is very efficient in generating offsprings of loading and response time histories conditional on the intermediate events with very low rejection rate, which facilities the application of ISp method to different kinds of stochastic single and multiple excitations. The effectiveness and accuracy of the proposed new scheme are verified by a reliability problem of earthquake-excited 5-story building, and by the estimation of extreme responses of a 5MW onshore wind turbine with very small exceeding probabilities. Finally, this framework is applied to validate the extrapolation procedure of estimating wind turbine long-term extreme responses with various mean recurrence intervals from short-term simulations of turbine response histories, which is mandated by current wind turbine design standards.

Recurrence intervals of major paleotsunamis as calibrated by historic tsunami deposits in three localities: Port Alberni, Cannon Beach, and Crescent City, along the Cascadia margin, Canada and USA

We review geologic records of both historic and prehistoric tsunami inundations at three widely separated localities that experienced significant damage from the 1964 Alaskan tsunami along the Cascadia margin. The three localities are Port Alberni, Cannon Beach, and Crescent City, representing, respectively, the north, central, and south portions of the study area (1,000 km in length). The geologic records include anomalous sand sheets from marine surges that are hosted in supratidal peaty mud deposits. Paleotsunami sand sheets that exceed the thickness, continuity and/or extent of the 1964 historic tsunami are counted as major paleotsunami inundations. Major paleotsunamis (6–7 in number) at each locality during the last 3,000 years demonstrate mean recurrence intervals of 450–540 years, and within-cluster intervals (three events each) of 270–460 years. It has been 313 years since the last major paleotsunami from a great Cascadia earthquake in AD 1700. We compare the dated sequences of major paleotsunami inundations to the nearest regional records of coastal coseismic subsidence in Willapa Bay in the central margin, Waatch/Neah Bay in the northern margin, and Coquille in the southern margin. Similar numbers of events from both types of records suggest that the major paleotsunamis are locally derived (near-field) from ruptures of the Cascadia margin megathrust fault zone, rather than from transoceanic tsunamis (far-field) originating at other subduction zones around the Pacific Rim. Given the catastrophic hazard of the near-field Cascadia margin tsunamis, we propose a basic rule for reminding the general public of the need for self-initiated evacuation following a great earthquake at the Cascadia margin.

Evaluation of Mean Recurrence Intervals of Wind Effects for Tall Building Design

AbstractMean recurrence intervals (MRIs) of wind effects for the strength design (SD) of flexible buildings by the wind-tunnel method are based on estimates of total uncertainties that do not accou...

Reliability of short seismic links in shear

This paper presents the results of research in reliability of short seismic links in shear based on tests. Four types of short links were analysed, each having the same cross section and the same length, but with different number of web stiffeners. The main purpose of the stiffeners is to preserve buckling of the seismic link web, i.e. to achieve plastification of the cross section by shear. The design model of shear resistance according to Eurocode 8 is applicable only to short links without web stiffeners. By adding the web stiffeners nonlinear inelastic behaviour of short seismic links differs depending on the number of stiffeners, so that the calculation model of shear resistance according to Eurocode 8 for short seismic link with stiffeners should be improved. This fact is considered by introducing the improve factors that were determined from the laboratory tests conducted on 16 specimens. On the base of tests in the second part of this paper the reliability of short seismic link is performed by forming limit state equations. These equations are formed by using the stochastic model, i.e. by describing the statistical nature of basic variables calculating the reliability index as an operational value of failure probability. The reliability level was determined by using the probabilistic analysis based on the first order reliability method (FORM) which resulted with the conclusion that the short seismic links with two and three couples of web stiffeners designed according to requirements of Eurocode 8 have enough reliability for the reliability class RC2 and the mean recurrence interval (MRI) of 50 years.

Performance Evaluation of Existing Bridges under Vehicle Dynamic Effects

This paper summarizes the recent work by the first author’s research group related to the performance evaluation of existing bridges under vehicle dynamic effects. Based on the data from short-term monitoring of existing bridges, a framework to estimate the extreme structure responses from the live load in a mean recurrence interval is developed in the first part. The Gumbel distribution of the extreme values was derived from an extreme value theory and Monte Carlo Simulation. In the second part, a framework of fatigue damage and reliability assessment for existing bridges is presented to include the effects of the progressively deteriorated road conditions and random dynamic vehicle loads in bridge’s life cycle. The random effects of vehicle speed and type, road profiles, and stress ranges are included. Studies have shown that the vehicle-induced dynamic allowance IM value prescribed by the AASHTO LRFD code may be underestimated under poor road surface conditions (RSCs) of some existing bridges. In addition, multiple dynamic stress ranges induced by vehicles cannot be included in the maximum displacement-based dynamic allowance IM values. In the third part of this paper, the reliability indices of a selected group of prestressed concrete girder bridges are calculated by modeling the IM explicitly as a random variable for different RSCs. Nevertheless, a reliability based dynamic amplification factor on stress ranges (DAFS) for fatigue design is proposed to include the fatigue damages from multiple stress range cycles due to each vehicle passage at varied vehicle speeds under various road conditions in the bridge’s life cycle.

Holocene Behavior of the Brigham City Segment: Implications for Forecasting the Next Large-Magnitude Earthquake on the Wasatch Fault Zone, Utah

The Brigham City segment (BCS), the northernmost Holocene‐active segment of the Wasatch fault zone (WFZ), is considered a likely location for the next big earthquake in northern Utah. We refine the timing of the last four surface‐rupturing (∼ M w 7) earthquakes at several sites near Brigham City (BE1, 2430±250; BE2, 3490±180; BE3, 4510±530; and BE4, ![Graphic][1] B.P.) and calculate mean recurrence intervals (1060–1500 yr) that are greatly exceeded by the elapsed time (∼2500 yr) since the most recent surface‐rupturing earthquake (MRE). An additional rupture observed at the Pearsons Canyon site (PC1, ![Graphic][2] B.P.) near the southern segment boundary is probably spillover rupture from a large earthquake on the adjacent Weber segment. Our seismic moment calculations show that the PC1 rupture reduced accumulated moment on the BCS about 22%, a value that may have been enough to postpone the next large earthquake. However, our calculations suggest that the segment currently has accumulated more than twice the moment accumulated in the three previous earthquake cycles, so we suspect that additional interactions with the adjacent Weber segment contributed to the long elapse time since the MRE on the BCS. Our moment calculations indicate that the next earthquake is not only overdue, but could be larger than the previous four earthquakes. Displacement data show higher rates of latest Quaternary slip (∼1.3 mm/yr) along the southern two‐thirds of the segment. The northern third likely has experienced fewer or smaller ruptures, which suggests to us that most earthquakes initiate at the southern segment boundary. Online Material: Cross sections, age estimates, evaluation of Box Elder delta earthquake chronology, code for OxCal models, trench logs, sources of surface offset data, and description of Call Fort gravel pit fault exposures. [1]: /embed/inline-graphic-1.gif [2]: /embed/inline-graphic-2.gif

Seismic moment rate and earthquake mean recurrence interval in the major tectonic boundaries around Oman

Owing to the short earthquake history, mathematical relationships were developed for calculating the earthquake recurrence from the rate of slip along the active faults. Based on the slip rate and the well-known Gutenberg–Richter law, various relationships between the earthquake occurrence parameters and the crustal deformation rates were developed. Among those is the widely used Molnar (1979 Bull. Seismol. Soc. Am. 69 115–33) mathematical expression, which is modified in the current study to produce a mathematical model based upon the truncated Gutenberg–Richter model instead of the normal Gutenberg–Richter one. The modified model is then tested and applied for the major tectonic boundaries around the Sultanate of Oman. The seismic moment rate is determined and the seismic hazard in terms of recurrence interval is expressed for the investigated regions. The calculated recurrence interval with moment magnitude 8.1 in the Makran zone is found to be 760 years, while for earthquakes with magnitude equal or greater than 5.8 in the Owen fracture zone is 4.904 years in consistency with the observed data. Recurrence intervals resulting from the original Molnar (1979) model and the current modified model were compared and discussed for the Zagros region.

Joint Wind-Snow Hazard Characterization for Reduced Reference Periods

AbstractThe joint behavior of snow and wind actions on structures becomes relevant for design in many regions of North America. With trends toward performance-based design for loads/actions arising from natural hazards, information is needed on both individual and joint hazards, e.g., at different hazard levels, exceedance probabilities, or mean recurrence intervals. The writers have developed one approach for two hazards that can be well modeled by sparse processes and have also developed recommendations for joint hazard characterization for the case of a full (e.g., 50 years) design life. The present paper shows how these findings can be extended to provide useful information for joint hazard characterization in shorter reference periods. This can be useful, for example, in the design (single or multiobjective) of formwork or other temporary structures in high wind/snow regions.

Seismites as a tool in the palaeoenvironmental reconstruction of fluvial deposits: The Cambrian Guarda Velha Formation, southern Brazil

Soft-sediment deformation (SSD) is widely described in the literature, but there is no clear consensus regarding its origin and significance. Existing models for SSD in fluvial sediments do not clearly demonstrate a relationship between the structures, preserved facies expression, and larger-scale depositional architecture. In this study several types of SSD structures are recorded in Cambrian fluvial deposits and these occur interbedded with undeformed strata throughout the entire stratigraphic interval. The random distribution of these features in relation to primary facies types and fluvial forms indicates that they have neither a direct nor indirect relationship with any depositional processes or bedform type. We propose that the relationship of SSD at the bed-set-scale to larger-scale depositional architecture, combined with tectono-stratigraphic analysis allows the determination of both short-term fluvial hydraulic conditions in ancient stream systems, such as the nature of the flow regime responsible for depositing ancient fluvial stream successions, and the long-term subsidence rates, in the form of mean recurrence interval of the seismic events responsible for triggering the generation of SSD in tectonically active basins.

An exceptionally long paleoseismic record of a slow-moving fault: The Alhama de Murcia fault (Eastern Betic shear zone, Spain)

Most catastrophic earthquakes occur along fast-moving faults, although some of them are triggered by slow-moving ones. Long paleoseismic histories are infrequent in the latter faults. Here, an exceptionally long paleoseismic record (more than 300 k.y.) of a slow-moving structure is presented for the southern tip of the Alhama de Murcia fault (Eastern Betic shear zone), which is characterized by morphological expression of current tectonic activity and by a lack of historical seismicity. At its tip, the fault divides into a splay with two main faults bounding the Gonar fault system. At this area, the condensed sedimentation and the distribution of the deformation in several structures provided us with more opportunities to obtain a complete paleoseismic record than at other segments of the fault. The tectonic deformation of the system was studied by an integrated structural, geomorphological, and paleoseismological approach. Stratigraphic and tectonic features at six paleoseismic trenches indicate that old alluvial units have been repeatedly folded and thrusted over younger ones along the different traces of the structure. The correlation of the event timing inferred for each of these trenches and the application of an improved protocol for the infrared stimulated luminescence (IRSL) dating of K-feldspar allowed us to constrain a paleoseismic record as old as 325 ka. We identified a minimum of six possible paleoearthquakes of M w = 6–7 and a maximum mean recurrence interval of 29 k.y. This provides compelling evidence for the underestimation of the seismic hazard in the region.

Paleoearthquakes of the past 30,000 years along the North Tehran Fault (Iran)

The North Tehran Fault (NTF) is located at the southernmost piedmont of Central Alborz and crosses the northern suburbs of the Tehran metropolis and adjacent cities, where ∼15 million people live. Extending over a length of about 110 km, the NTF stands out as a major active fault and represents an important seismic hazard for the Iranian capital after historical seismicity. In order to characterize the activity of the NTF in terms of kinematics, magnitude and recurrence intervals of earthquakes, we carried out a first paleoseismological study of the fault within its central part between Tehran and Karaj cities. We opened a trench across a 3 m‐high fault scarp affecting Quaternary deposits. Our study shows that the scarp is the result of repeated events along a main N115°E trending shallow dipping thrust fault, associated with secondary ruptures. From the trench analysis and Infrared Stimulated Luminescence (IRSL) dating of fault‐related sediments, we interpreted between 6 and 7 surface‐rupturing events that occurred during the past 30 kyrs. Their magnitudes (estimated from the displacements along the faults) are comprised between 6.1 and 7.2. The two last events – the largest ‐ occurred during the past 7.9 ± 1.2 ka, which yields a Holocene slip rate of ∼0.3 mm/yr. The 7 earthquakes scenario suggests a regular periodicity with a mean recurrence interval of ∼3.8 kyrs. However, the two most recent events could correspond to the two largest historical earthquakes recorded in the area (in 312–280 B.C. and 1177 A.D.), and therefore suggest that the NTF activity is not regular.

A fault and seismicity based composite simulation in northern California

Abstract. We generate synthetic catalogs of seismicity in northern California using a composite simulation. The basis of the simulation is the fault based "Virtual California" (VC) earthquake simulator. Back-slip velocities and mean recurrence intervals are specified on model strike-slip faults. A catalog of characteristic earthquakes is generated for a period of 100 000 yr. These earthquakes are predominantly in the range M = 6 to M = 8, but do not follow Gutenberg-Richter (GR) scaling at lower magnitudes. In order to model seismicity on unmapped faults we introduce background seismicity which occurs randomly in time with GR scaling and is spatially associated with the VC model faults. These earthquakes fill in the GR scaling down to M = 4 (the smallest earthquakes modeled). The rate of background seismicity is constrained by the observed rate of occurrence of M > 4 earthquakes in northern California. These earthquakes are then used to drive the BASS (branching aftershock sequence) model of aftershock occurrence. The BASS model is the self-similar limit of the ETAS (epidemic type aftershock sequence) model. Families of aftershocks are generated following each Virtual California and background main shock. In the simulations the rate of occurrence of aftershocks is essentially equal to the rate of occurrence of main shocks in the magnitude range 4 < M < 7. We generate frequency-magnitude and recurrence interval statistics both regionally and fault specific. We compare our modeled rates of seismicity and spatial variability with observations.

Integration of Paleoseismic Data from Multiple Sites to Develop an Objective Earthquake Chronology: Application to the Weber Segment of the Wasatch Fault Zone, Utah

We present a method to evaluate and integrate paleoseismic data from multiple sites into a single, objective measure of earthquake timing and recurrence on discrete segments of active faults. We apply this method to the Weber segment (WS) of the Wasatch fault zone using data from four fault-trench studies completed between 1981 and 2009. After systematically reevaluating the stratigraphic and chro- nologic data from each trench site, we constructed time-stratigraphic OxCal models that yield site probability density functions (PDFs) of the times of individual earth- quakes. We next qualitatively correlated the site PDFs into a segment-wide earthquake chronology, which is supported by overlapping site PDFs, large per-event displace- ments, and prominent segment boundaries. For each segment-wide earthquake, we computed the product of the site PDF probabilities in common time bins, which emphasizes the overlap in the site earthquake times, and gives more weight to the narrowest, best-defined PDFs. The product method yields smaller earthquake-timing uncertainties compared to taking the mean of the site PDFs, but is best suited to earth- quakes constrained by broad, overlapping site PDFs. We calculated segment-wide earthquake recurrence intervals and uncertainties using a Monte Carlo model. Five surface-faulting earthquakes occurred on the WS at about 5.9, 4.5, 3.1, 1.1, and 0.6 ka. With the exception of the 1.1-ka event, we used the product method to define the earthquake times. The revised WS chronology yields a mean recurrence interval of 1.3 kyr (0.7-1.9-kyr estimated two-sigma (2σ) range based on interevent recurrence). These data help clarify the paleoearthquake history of the WS, including the important question of the timing and rupture extent of the most recent earthquake, and are essential to the improvement of earthquake-probability assessments for the Wasatch Front region.

Similarities and Differences in the Rupture Process of the M 4.8 Repeating-Earthquake Sequence off Kamaishi, Northeast Japan: Comparison between the 2001 and 2008 Events

Earthquakes of M ∼5 have repeatedly occurred at the same location on the plate boundary off Kamaishi, northeast Japan, with a mean recurrence interval of about 5.5 years. The latest two events ( M 4.8 on 13 November 2001, and M 4.7 on 11 January 2008) were successfully observed by the broadband seismic network of Tohoku University covering the Tohoku District of northeast Japan. We estimated the source processes of the 2001 and 2008 events by carefully picking the onsets of P and S waves and by inverting seismic waveforms recorded by the network. The results show that both events were caused by the rupture of the same asperity patch (diameter, ∼1 km). As the previous 1995 event was also reported to have ruptured the source area of the 2001 event, at least the last three events (1995, 2001, and 2008) in this earthquake sequence are thought to have been caused by repeated ruptures of the same asperity. A closer examination, however, reveals a small discrepancy in the slip distribution between the last two events, which explains the difference in the high-frequency components of the seismograms. The regions in which slip was smaller during the 2001 event than during the 2008 event nearly coincide with the source areas of the smaller repeating earthquakes that occurred just before the 2001 event. This finding suggests that the activity of smaller events immediately before the mainshock can influence the slip distribution of the mainshock.

Flank collapse scenarios at Volcán de Colima, Mexico: A relative instability analysis

Previous studies on debris avalanche deposits of Volcán de Colima suggest a cyclic process of repetitive flank collapses triggered by major eruptions (VEI > 4). The recurrence interval of major collapse events during the last 10,000 years is calculated here using a stochastic approach, yielding a mean recurrence interval of 2698 yr, with an uncertainty range of 180 yr. The analysis yields an increased probability of flank collapse in the interval between − 110 yr and + 345 yr from the present. This generates a series of scenarios ranging from optimistic, considering a collapse within the next 345 years, to pessimistic, derived from the 110 year delay. The analysis of relative mass/volume deficit in the volcano structure, made using the new VOLCANOFIT 2.0 software, and a limit equilibrium analysis on the volcano flanks point to the SW quadrant as potentially the most unstable sector of the edifice under a wide range of scenarios. The TITAN2D numerical model is also used to simulate the extent of debris avalanches caused by failure of the SW flank. This approach may be applied to any volcano with a potential for flank collapse.

Slip rate and slip magnitudes of past earthquakes along the Bogd left-lateral strike-slip fault (Mongolia)

We carried out morphotectonic studies along the left-lateral strike-slip Bogd Fault, the principal structure involved in the Gobi-Altay earthquake of 1957 December 4 (published magnitudes range from 7.8 to 8.3). The Bogd Fault is 260 km long and can be subdivided into five main geometric segments, based on variation in strike direction. West to East these segments are, respectively: the West Ih Bogd (WIB), The North Ih Bogd (NIB), the West Ih Bogd (WIB), the West Baga Bogd (WBB) and the East Baga Bogd (EBB) segments. Morphological analysis of offset streams, ridges and alluvial fans-particularly well preserved in the arid environment of the Gobi region-allows evaluation of late Quaternary slip rates along the different faults segments. In this paper, we measure slip rates over the past 200 ka at four sites distributed across the three western segments of the Bogd Fault. Our results show that the left-lateral slip rate is similar to 1 mm yr(-1) along the WIB and EIB segments and similar to 0.5 mm yr(-1) along the NIB segment. These variations are consistent with the restraining bend geometry of the Bogd Fault.;Our study also provides additional estimates of the horizontal offset associated with the 1957 earthquake along the western part of the Bogd rupture, complementing previously published studies. We show that the mean horizontal offset associated with the 1957 earthquake decreases progressively from 5.2 m in the west to 2.0 m in the east, reflecting the progressive change of kinematic style from pure left-lateral strike-slip faulting to left-lateral-reverse faulting. Along the three western segments, we measure cumulative displacements that are multiples of the 1957 coseismic offset, which may be consistent with a characteristic slip. Moreover, using these data, we re-estimate the moment magnitude of the Gobi-Altay earthquake at M-w 7.78-7.95.;Combining our slip rate estimates and the slip distribution per event we also determined a mean recurrence interval of similar to 2500-5200 yr for past earthquakes along the different segments of the western Bogd Fault. This suggests that the three western segments of the Bogd Fault and the Gurvan Bulag thrust fault (a reverse fault bounding the southern side of the Ih Bogd range that ruptured during the 1957 earthquake) have similar average recurrence times, and therefore may have ruptured together in previous earthquakes as they did in 1957. These results suggest that the western part of the Bogd Fault system, including the Gurvan Bulag thrust fault, usually behaves in a 'characteristic earthquake' mode.

Evaluation of the use of paleotsunami deposits to reconstruct inundation distance and runup heights associated with prehistoric inundation events, Crescent City, southern Cascadia margin

ABSTRACTHistoric‐ and prehistoric‐tsunami sand deposits are used to independently establish runup records for tsunami hazard mitigation and modeled runup verification in Crescent City, California, located in the southern Cascadia Subduction Zone. Inundation from historic (1964) farfield tsunami (~5–6 m runup height) left sand sheet deposits (100–200 m width) in wetlands located behind a low beach ridge [3–4 m elevation of the National Geodetic Vertical Datum of 1988 (NAVD88)]. The most landward flooding lines (4·5–5 m elevation) in high‐gradient alluvial wetlands exceed the 1964 sand sheet records of inundation by 1–2 m in elevation. The most landward flooding in low‐gradient alluvial wetlands exceed the corresponding sand sheet record of inundation distance by 1000 m. Nevertheless, the sand sheet record is an important proxy for high‐velocity inundation. Sand sheet deposition from the 1964 historic tsunami closely corresponds to the landward extent of large debris transport and structural damage in the Crescent City waterfront. The sand sheet deposits provide a proxy for maximum hazard or ‘kill zone’ in the study area.Six paleotsunami sand sheets (0·3–3 ka) are recorded in the back‐ridge marshes in Crescent City, yielding a ~450 year mean recurrence interval for nearfield Cascadia tsunami. Two paleotsunami sand deposit records, likely correlated to Cascadia ruptures between 1·0 and 1·5 ka, are traced to 1·2 km distance and 9–10 m elevation, as adjusted for paleo‐sea level. The paleotsunami sand deposits demonstrate at least twice the runup height, and four times the inundation distance of the farfield 1964 tsunami sand sheet in the same marsh system. The preserved paleotsunami deposits in Crescent City are compared to the most landward flooding, as modeled by other investigators from a predicted Cascadia (~ Mw 9) rupture. The short geologic record (~1·5 ka) yields slightly lower runup records than those predicted for the modeled Mw 9 rupture scenario in the same marsh, but it generally verifies predicted maximum tsunami runup for use in the planning of emergency response and rapid evacuation. Copyright © 2011 John Wiley & Sons, Ltd.

Assessment and management of coastal multi-hazard vulnerability along the Cuddalore–Villupuram, east coast of India using geospatial techniques

The current study area is coastal zone of Cuddalore, Pondicherry and Villupuram districts of the Tamil Nadu along the southeast coast of India. This area is experiencing threat from many disasters such as storm, cyclone, flood, tsunami and erosion. This was one of the worst affected area during 2004 Indian Ocean tsunami and during 2008 Nisha cyclone. The multi-hazard vulnerability maps prepared here are a blended and combined overlay of multiple hazards those affecting the coastal zone. The present study aims to develop a methodology for coastal multi-hazard vulnerability assessment. This study was carried out using parameters probability of maximum storm surge height during the return period (mean recurrence interval), future sea level rise, coastal erosion and high resolution coastal topography with the aid of the Remote Sensing and GIS tools. The assessment results were threatening 3.46 million inhabitants from 129 villages covering a coastal area 360 km 2 under the multi-hazard zone. In general river systems act as the flooding corridors which carrying larger and longer hinterland inundation. Multi-hazard Vulnerability maps were further reproduced as risk maps with the land use information. These risk caused due to multi-hazards were assessed up to building levels. The decision-making tools presented here can aid as critical information during a disaster for the evacuation process and to evolve a management strategy. These Multi-hazard vulnerability maps can also be used as a tool in planning a new facility and for insurance purpose.