Numerical Simulations of Tsunami Waves and Currents for Southern Vancouver Island from a Cascadia Megathrust Earthquake

The 1700 great Cascadia earthquake (M = 9) generated widespread tsunami waves that affected the entire Pacific Ocean and caused damage as distant as Japan. Similar catastrophic waves may be generated by a future Cascadia megathrust earthquake. We use three rupture scenarios for this earthquake in numerical experiments to study propagation of tsunami waves off the west coast of North America and to predict tsunami heights and currents in several bays and harbours on southern Vancouver Island, British Columbia, including Ucluelet, located on the west coast of the island, and Victoria and Esquimalt harbours inside Juan de Fuca Strait. The earthquake scenarios are: an 1100-km long rupture over the entire length of the subduction zone and separate ruptures of its northern or southern segments. As expected, the southern earthquake scenario has a limited effect over most of the Vancouver Island coast, with waves in the harbours not exceeding 1 m. The other two scenarios produce large tsunami waves, higher than 16 m at one location near Ucluelet and over 4 m inside Esquimalt and Victoria harbours, and very strong currents that reach 17 m/s in narrow channels and near headlands. Because the assumed rupture scenarios are based on a previous earthquake, direct use of the model results to estimate the effect of a future earthquake requires appropriate qualification.     

FOREWORD

Foreword

FOREWORD     

Layered Velocity Models of the Western Bohemia Region

A new robust and effective optimization algorithm – isometric algorithm – was used for the inversion of layered velocity models, with constant gradient in each layer, to find suitable 1-D models for the location of microearthquakes in the individual four subregions of the West Bohemian earthquake swarm region. Models which are considered as optimal yield the minimum sum of the absolute values of the travel-time residua in locating the whole group of earthquakes in the given subregion. The results obtained from the inversion of P and S waves and from P waves only are shown. For comparison, optimum homogeneous models derived by the grid search method, again using both P and S waves and P waves only, are given. The computations indicate that the models for the individual subregions differ from each other. For layered models the differences are more pronounced, as expected, in the upper parts, down to depths of about 5 km. In comparison with the subregions Nový Kostel and Plesná, the P and S wave velocities for subregion Lazy are relatively higher and the P and S velocities for subregion Klingenthal relatively lower. In the lower parts the differences are smaller and the velocities have practically identical gradients. The highest velocities were obtained for subregion Lazy and the lowest velocities for subregion Klingenthal, as well for the homogeneous models. The model that represents the whole swarm region was determined in a similar way. This model is compared with the previously published velocity-depth distribution, obtained from DSS profile VI/70 in the vicinity of the area under study.     

Veränderung im mikrobiellen Zelluloseabbau im Bodensee infolge der fortschreitenden Eutrophierung sowie als Vergleich im eutrophen Schleinsee und zwei verschieden stark belasteten Bodenseezuflüssen

Ohne Zusammenfassung Herrn Direktor Dr. W. Nümann zum 65. Geburtstag. Mit Unterstützung der Deutschen Forschungsgemeinschaft, Bad Godesberg.     

Limnologische Charakterisierung des Lauerzersees mit besonderer Berücksichtigung des Planktons

Ohne Zusammenfassung     

Der Verlauf der Madelungschen Zahl für den Wurtzit-Typ bei Änderung des Achsenverhältnisses

Zusammenfassung Madelungsche Zahlen für den Wurtzit-Typ wurden für verschiedene Achsenverhältnisse berechnel, jedoch mit der Spezialisierung, daß die beiden nicht äquivalenten A-B-Abstände im Koordinationspolyeder in allen Modellen genau gleich lang sind. Die Madelungsche Zahl wächst mit abnehmendem Achsenverhältnis; das erklärt die Tendenz der stärker ionaren Vertreter dieses Strukturlyps zu einem kleineren Achsenverhältnis als dem Idealwert .

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Summary Madelung numbers for the wurtzite-type have been calculated for different axial ratios, but with the specialization that the two not equivalent kinds of A-B-distances in the coordination polyhedron are exactly of equal length in all models. The Madelung number increases with decreasing axial ratio; this explains the tendency of the more ionic members of this structure type to have axial ratios smaller than the ideal value .

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Mit 1 Textabbildung     

Das Erdstrom-Observatorium bei Nagycenk (Ungarn)

Zusammenfassung Im ersten Teil des Artikels werden — nach einem kurzen geschichtlichen Rückblick — die Anlage und die technischen Einrichtungen des im IGJ bei Nagycenk (Ungarn) errichteten tellurischen Observatoriums dargelegt. Der zweite Teil beschäftigt sich mit der Bearbeitung der Registrierungen. Wir wollen in erster Richtung die Verteilung der Variationen von verschiedenen Perioden untersuchen, und wir ordneten deshalb, teils auf Grund der Gegebenheiten der Registrierungen, hauptsächlich aber der Untersuchung bei verschiedenen Typen wegen, die Variationen in 5, bzw.9 Klassen ein. Ausserdem führen wir die tellurischen Äquivalenten der magnetischen Phenomena (Bay, Sturm, usw) und die Grundlagen deren Einteilung an. Die Publikationen über Karakteristiken und Graphikons zweccks Erkennung der Eigenschaften der Variationen werden wir von Zeit zu Zeit forsetzen.

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Summary In the first part of the article the writers — after a brief historical note — acquaint with the question of the location of the telluric observatory, established during the IGY near Nagycenk (Hungary) and with its technical arrangements. The second part presents the preparation of the records. It was chiefly the distribution of the different periodic variations in our mind, and this is why we included the variations, partly based on the given conditions of the recording, but in first line on the examination of periods of the different types in 5, respectively in 9 classes. Moreover, we specify the telluric equivalents of magnetic phenomena (bay, storm, etc.) and the basic principles of the classification. We shall report periodically on the characterics and graphs concerning the feature of the variations.