Potential secondary events caused by early Holocene paleoearthquakes in Fennoscandia – a climate-related review

During the last deglaciation of Fennoscandia, large earthquakes may have induced secondary effects on the high-latitude coastal regions and continental margins primarily from surface rock avalanches, large and small submarine slides, local and regional flooding, and tsunamis. In this overview, we show that the climate-earthquake-slide-tsunami causal sequence is particularly important, as is structural inheritance and rejuvenation. However, there are potential earthquake-generating early Holocene faults also beyond the previously defined Lapland Fault Province. Thus, we introduce the term the Greater Lapland Fault Province. Earthquakes in the expanded fault province are candidates for triggering the 8.1 ka Storegga Megaslide and/or its predecessors and coeval tsunamis. The events might have released other submarine slides, gas hydrate expulsion leaving large pockmark fields, rock avalanches and submarine mass wasting in fjord and lake settings. Moreover, the seismic events may also have triggered local and regional flooding by breakup of ice and sediment barriers.publishedVersio

Ground-motion prediction equations for southern Spain and southern Norway obtained using the composite model perspective

In this paper, two sets of earthquake ground-motion relations to estimate peak ground and response spectral acceleration are developed for sites in southern Spain and in southern Norway using a recently published composite approach. For this purpose seven empirical ground-motion relations developed from recorded strong-motion data from different parts of the world were employed. The different relations were first adjusted based on a number of transformations to convert the differing choices of independent parameters to a single one. After these transformations, which include the scatter introduced, were performed, the equations were modified to account for differences between the host and the target regions using the stochastic method to compute the host-to-target conversion factors. Finally functions were fitted to the derived ground-motion estimates to obtain sets of seven individual equations for use in probabilistic seismic hazard assessment for southern Spain and southern Norway. The relations are compared with local ones published for the two regions. The composite methodology calls for the setting up of independent logic trees for the median values and for the sigma values, in order to properly separate epistemic and aleatory uncertainties after the corrections and the conversions

Dealing with Tsunami Risk - A Case Study for Thailand

The December 26 2004 tsunami event devastated large areas along the coastlines of Indonesia, Thailand, Myanmar, Sri Lanka and India, and even some parts of the east African coastline. It is a great challenge to the authorities in the countries affected by the tsunami to deal with the future risk of tsunami events and how to rehabilitate the devastated areas under consideration of that risk. On initiative from the Norwegian Geotechnical Institute (NGI), a project has been initiated to help develop a rehabilitation strategy in Thailand, but it is also intended as serve as an example project for other countries in the region. The project is undertaken for the Department of Mineral Resources (DMR) under the Ministry of Natural Resources and the Environment in Thailand, and is undertaken by NGI in cooperation with CCOP. The project is fully financed by the Royal Norwegian Ministry of Foreign Affairs. The paper describes the various components of the project, including: 1. Identification of possible future seismic and tsunami-triggering dislocation scenarios, and their associated risk level. This will involve a detailed study of the plate tectonics in the region and earthquake statistics, including correlations between earthquake magnitude and possible dislocations causing tsunamis. 2. Analyses of possible tsunami inundation levels for the various seismic scenarios and their possible consequences. A first step will be to verify that available tsunami and inundation models can predict the observations in connection with the December 2004 event on both global and local levels. 3. Assessment of possible measures to reduce or eliminate the potential consequences of future tsunamis. That may include physical barriers, vertical land reclamation, strengthening of buildings/new building codes, and development of new urban and city plans with focus on establishing safe “islands” and escape routes and placement of critical functions in safe areas. 4. Propose overall and specific reconstruction and rehabilitation plans for three typical selected areas along the coast in Thailand. Such plans will have both a short term and long term perspective

Spectral Strong Motion Attenuation in Central America

A bayesian regression analysis of response spectral ordinates based on 218 digitized strong ground motion accelerograms (largest horizontal component) from Central America, augmented by 62 similar, high-magnitude observations from Guerrero, Mexico, has been performed using the simple linearized ground motion model: lnA = c1 + c2M + c3lnr +c4r = c5S + ln e where M is moment magnitude, r is hypocentral distance, S is zero for rock sites and 1 for soil sites and In£ is a normally distributed error term with zero mean and standard deviation sigma i.e. ln e = N (0, sigma) .Universidad de Costa Rica/[]/UCR/Costa RicaNorwegian Agency for International Cooperation/[]/NORAD/OsloInstituto Costarricense de Electricidad/[]/ICE/Costa RicaInstituto Nicaragüense de Estudios Territoriales/[]/INETER/NicaraguaCentro de Investigaciones Geotecnicas/[]/CIG/El SalvadorUniversidad Autónoma de México/[]/UNAM/MéxicoUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ingeniería::Instituto Investigaciones en Ingeniería (INII

The challenge of defining upper bounds on earthquake ground motions

Recent studies to assess very long-term seismic hazard in the United States and in Europe have brought the issue of upper limits on earthquake ground motions into the arena of problems requiring attention from the engineering seismological community. Few engineering projects are considered sufficiently critical to warrant the use of annual frequencies of exceedance so low that ground-motion estimates may become unphysical if limiting factors are not considered, but for nuclear waste repositories, for example, the issue is of great importance. The definition of upper bounds on earthquake ground motions also presents an exciting challenge for researchers in the area of seismic hazard assessment. This paper looks briefly at historical work on maximum values of ground-motion amplitudes before illustrating why this is an important issue for hazard assessments at very long return periods. The paper then discusses the factors that control the extreme values of motion, both in terms of generating higher amplitude bedrock motions and of limiting the values of motion at the ground surface. Possible channels of research that could be explored in the quest to define maximum possible ground motions are also discussed

The European Plate Observing System and the Arctic

The European Plate Observing System (EPOS) aims to integrate existing infrastructures in the solid earth sciences into a single infrastructure, enabling earth scientists across Europe to combine, model, and interpret multidisciplinary datasets at different time and length scales. In particular, a primary objective is to integrate existing research infrastructures within the fields of seismology, geodesy, geophysics, geology, rock physics, and volcanology at a pan-European level. The added value of such integration is not visible through individual analyses of data from each research infrastructure; it needs to be understood in a long-term perspective that includes the time when changes implied by current scientific research results are fully realized and their societal impacts have become clear. EPOS is now entering its implementation phase following a four-year preparatory phase during which 18 member countries in Europe contributed more than 250 research infrastructures to the building of this pan-European vision. The Arctic covers a significant portion of the European plate and therefore plays an important part in research on the solid earth in Europe. However, the work environment in the Arctic is challenging. First, most of the European Plate boundary in the Arctic is offshore, and hence, sub-sea networks must be built for solid earth observation. Second, ice covers the Arctic Ocean where the European Plate boundary crosses through the Gakkel Ridge, so innovative technologies are needed to monitor solid earth deformation. Therefore, research collaboration with other disciplines such as physical oceanography, marine acoustics, and geo-biology is necessary. The establishment of efficient research infrastructures suitable for these challenging conditions is essential both to reduce costs and to stimulate multidisciplinary research.Le système European Plate Observing System (EPOS) vise l’intégration des infrastructures actuelles en sciences de la croûte terrestre afin de ne former qu’une seule infrastructure pour que les spécialistes des sciences de la Terre des quatre coins de l’Europe puissent combiner, modéliser et interpréter des ensembles de données multidisciplinaires moyennant diverses échelles de temps et de longueur. Un des principaux objectifs consiste plus particulièrement à intégrer les infrastructures de recherche existantes se rapportant aux domaines de la sismologie, de la géodésie, de la géophysique, de la géologie, de la physique des roches et de la volcanologie à l’échelle paneuropéenne. La valeur ajoutée de cette intégration n’est pas visible au moyen des analyses individuelles des données émanant de chaque infrastructure de recherche. Elle doit plutôt être considérée à la lumière d’une perspective à long terme, lorsque les changements qu’impliquent les résultats de recherche scientifique actuels auront été entièrement réalisés et que les incidences sur la société seront claires. Le système EPOS est en train d’amorcer sa phase de mise en oeuvre. Cette phase succède à la phase préparatoire de quatre ans pendant laquelle 18 pays membres de l’Europe ont soumis plus de 250 infrastructures de recherche en vue de l’édification de cette vision paneuropéenne. L’Arctique couvre une grande partie de la plaque européenne et par conséquent, il joue un rôle important dans les travaux de recherche portant sur la croûte terrestre en Europe. Cependant, le milieu de travail de l’Arctique n’est pas sans défis. Premièrement, la majorité de la limite de la plaque européenne se trouvant dans l’Arctique est située au large, ce qui signifie que des réseaux marins doivent être aménagés pour permettre l’observation de la croûte terrestre. Deuxièmement, de la glace recouvre l’océan Arctique, là où la limite de la plaque européenne traverse la dorsale de Gakkel, ce qui signifie qu’il faut recourir à des technologies innovatrices pour surveiller la déformation de la croûte terrestre. C’est pourquoi les travaux de recherche doivent nécessairement se faire en collaboration avec d’autres disciplines comme l’océanographie physique, l’acoustique marine et la géobiologie. L’établissement d’infrastructures de recherche efficaces capables de faire face à ces conditions rigoureuses s’avère essentiel, tant pour réduire les coûts que pour stimuler la recherche multidisciplinaire

Potential secondary events caused by early Holocene paleoearthquakes in Fennoscandia – a climate-related review

During the last deglaciation of Fennoscandia, large earthquakes may have induced secondary effects on the high-latitude coastal regions and continental margins primarily from surface rock avalanches, large and small submarine slides, local and regional flooding, and tsunamis. In this overview, we show that the climate-earthquake-slide-tsunami causal sequence is particularly important, as is structural inheritance and rejuvenation. However, there are potential earthquake-generating early Holocene faults also beyond the previously defined Lapland Fault Province. Thus, we introduce the term the Greater Lapland Fault Province. Earthquakes in the expanded fault province are candidates for triggering the 8.1 ka Storegga Megaslide and/or its predecessors and coeval tsunamis. The events might have released other submarine slides, gas hydrate expulsion leaving large pockmark fields, rock avalanches and submarine mass wasting in fjord and lake settings. Moreover, the seismic events may also have triggered local and regional flooding by breakup of ice and sediment barriers

Modeling spatial and temporal dependencies between earthquakes

Two new different stochastic models for earthquake occurrence are discussed. Both models are focusing on the spatio-temporal interactions between earthquakes. The parameters of the models are estimated from a Bayesian updating of priors, using empirical data to derive posterior distributions. The first model is a marked point process model in which each earthquake is represented by its magnitude and coordinates in space and time. This model incorporates the occurrence of aftershocks as well as the build-up and subsequent release of strain. The second model is a hierarchical Bayesian space-time model in which the earthquakes are represented by potentials on a grid. The final ambition of the models is to make predictions on the occurrence of earthquakes

Historical and recent earthquakes in Central America

A comprehensive data base of about 17000 historical and recent earthquakes has been established for the Central American region, based on existing research and reports from Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica and Panama. The catalog includes known damaging historic earthquakes, as well as the more important of the recent data, including both macroseismic and instrumental observations. The catalog starts in the beginning of the 16th century and is limited to macroseismic data (reeported phenomena and associated damage) until 1902, while it for the time since then contains both macroseismic and instrumental observations. Recent local network solutions are normally included only for events above magnitude 3.5.The new catalog is considered to be reasonable complet for earthquakes with magnitudes MS ≥5.5 back to around year 1900, and for MS  ≥7 back to around year 1820, and it should have the capabilities of further assisting the ongoing efforts towards a more reliable evaluation of the seismogenic potentials in the region. The catalog infomation has been used in this paper for developing new relations between body wave magnitude mb and surface wave magnitude MS, between mb and local magnitude ML, and between MS and ML. New relations have also been developed between mb, MS and ML and maximum intensity Imax, between ML and felt radius, and between ML and felt area for intensity levels between III and VIII. Such relations are potentially important for a further development and improvement of the magnitude assessments for both newer and older earthquakes, as well as for many questions related to earthquake engineering.Las investigaciones sobre la sismicidad histórica en América Central, hasta ahora, a excepción de algunos pocos casos, han sido enfocadas hacia estudios individuales por país. Sin embargo, es frecuente que las regiones limítrofes de esos países, correspondan con estructuras tectónica de importancia, lo que conduce a la necesidad de efectuar un estudio integrado de la información existente de cada país y, de esa forma, emprender mejor la situación geotectónica. Por ello, la presente investigación cristalizó en un catálogo integrando los datos históricos, con observaciones instrumentales de la sismicidad en la región, basado en investigaciones y reportes procedentes de Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica y Panamá. El presente banco de datos es considerado razonablemente completo para sismos con magnitud MS igual o mayor de 5,5 a partir del año 1900, y para MS igual o mayor de 7,0 desde alrededor de 1820 al presente. De hecho, aún queda mucho trabajo por hacer a fin de mejorar el catálogo, en particular para los siglos XVI, XVII y XVIII, esperando que la manera con que esta base de datos ha sido organizada, pueda ser de utilidad, sirviendo como guía para futuras investigaciones que contribuyan a mejorarlo. Aunque el propósito principal de la presente investigación fue la compilación de la información sismológica, se han incluido además algunas aplicaciones y análisis en términos de correlación entre diferentes magnitudes (M), entre M e intensidades (a diferentes niveles de intensidad), entre M y aceleraciones, entre M y el radio de perceptibilidad y entre M y el área sentida. Al respecto, han sido incluidas algunas de esas correlaciones en vista de que los resultados obtenidos resultan interesantes y, porque en parte demuestran el potencial de la base de datos establecida. La intesión del catálogo ha sido la de incluir todos los terremotos históricos que han provocado algún daño de importancia, además de los datos recientes más relevantes, incluyendo tanto la información macrosísmica como los datos provenientes de les redes de instrumentación. En la región de Centroamérica, el primer evento sísmica localizado en forma instrumental, es el de 1902 (M=7,9), en la costa pacífica de Guatemala. La información del catálogo que comprende desde el siglo XVI hasta 1902, se limita a datos macrosísmicos (basados en observaciones del fenómeno y daños asociados), mientras que a partir de 1902 hasta el presente contiene tanto información macrosísmica como los datos obtenidos con instrumentación. De acuerdo con la interpretación de los registros procedentes de instrumentos sismográficos y de datos históricos, los eventos superficiales (h menor de 20 km) que causan mayor daño corresponden a los de magnitud M o MS igual o mayor de 6. Sin embargo, hay eventos dañinos algunas veces asociados a ruptura cortical somera, ubicadas a lo largo del arco volcánico de Centroamérica, que no han sido registrados en los catálogos internacionales, a pesar de haber ocurrido durante el período instrumental. Las observaciones sugieren que esos sismos (ahora incluidos en el catálogo) generalmente poseen valores de magnitud inferiores a 6,0.El presente catálogo sismológieo de América Central, puede ser usado en una variedad de aplicaciones, en particular para el análisis del riesgo sísmico y en general, para estudios sobre el potencial sísmico de la región