The use of body-wave spectra in the determination of seismic-source parameters

Teleseismic determinations of body-wave (P, S) spectra, interpreted in terms of the Brune (1970) seismic-source model, are used to estimate the parameters seismic moment (M_o) and source dimension (r) for three large, shallow, strike-slip earthquakes occurring on nearly vertical fault planes and for which the same parameters can be determined from field (F) data. These earthquakes are (1) the Borrego Mountain, California, earthquake (April 9, 1968) for which [M̅_o(P) = 10, M̅_o(S) = 6.6, and M_o(F) = 3.6] × 10^(25) dyne-cm and [r̅(p) = 14, r̅(S) = 23, and L/2(F) = 17] km; (2) the Mudurnu Valley, Turkey, earthquake (July 22, 1967) for which [M̅_o(P) = 9.1, M̅_o(S) = 8.5, and M_o(F) = 7.4] × 10^(26) dyne-cm, and [r̅(P) = 39, r̅(S) = 48, and L/2(F) = 40] km; and (3) the Dasht-e-Bayāz, Iran, earthquake (August 31, 1968) for which [M̅_o(P) = 4.8, M̅_o(S) = 8.6, and M_o(F) = 18] × 10^(26) dyne-cm, and [r̅(P) = S1, r̅(S) = 48, and L/2(F) = 40] km. The Brune (1970) model is well-calibrated with respect to the determination of these parameters for the earthquakes considered. A minimum estimate for the radiated energy can be expressed in terms of M_o and r; this estimate is low by a factor of 10 with respect to the estimate obtained from energy-magnitude relations for these three earthquakes. The stress drops of these events are of the order of 10 bars

Displacement on the San Andreas fault subsequent to the 1966 Parkfield earthquake

Immediately following the 1966 Parkfield earthquake a continuing program of fault displacement measurements was undertaken, and several types of instruments were installed in the fault zone to monitor ground motion. In the year subsequent to the earthquake a maximum of at least 20 cm of displacement occurred on a 30 km section of the San Andreas fault, which far exceeded the surficial displacement at the time of the earthquake. The rate of displacement decreased logarithmically during this period in a manner similar to that of the decrease in aftershock activity. After the initial high rate of activity it could be seen that most of the displacement was occurring in 4–6 day epochs of rapid creep following local aftershocks. The variation of fault displacement along the surface trace was measured and shown to be consistent with a vertidal fault surface 44 km long and 14 km deep, along which a shear stress of 2.4 bars was relieved

Regional variations of source properties in southern California estimated from the ratio of short- to long-period amplitudes

The ratio of short- to long-period amplitude is expressed in terms of apparent stress, rigidity times energy over moment (μE_G/M_0), for 277 earthquakes in California. A map showing the apparent stresses is compiled. In general, the Mendocino and San Andreas faults as well as the Gulf of California area are regions of large surface-wave excitation and little short-period radiation (low apparent stress). Away from the main fault zones, the apparent stresses tend to be higher. Regions of conspicuously low surface-wave excitation (high apparent stress) are the Laguna Salada-Sierra Juarez region in northern Baja California, the California-Nevada border region north of Bishop, and the region associated with the bend of the San Andreas between San Bernardino and San Gorgonio Mountain. A detailed comparison of earthquakes with accurately-known depths at Parkfield and Borrego Mountain indicates two important differences in apparent stresses between these two source regions. The apparent stress at all depths is larger at Borrego Mountain than at Parkfield, and it increases with depth at Borrego Mountain, whereas it remains constant at all depths at Parkfield. The explanation for the variation of surface-wave excitation (apparent stress) is not known for certain, but it could be related to variations in true stress

The source parameters of the San Fernando earthquake inferred from teleseismic body waves

The accuracy of teleseismic estimates of moment, fault area, dislocation and stress drop was tested for the case of a thrust fault: the San Fernando, California, earthquake of February 9, 1971. On the basis of P-wave spectra of 25 stations and S-wave spectra of 9 stations, the respective values were found to be 0.7 · 10^(26) dyne-cm, 570 km^2, 45 cm, and 14 bars. They agree well with the same parameters obtained from field observations. It is concluded that Brune's (1970) seismic source model is valid for the area determination of thrust earthquakes. The energy radiated in the form of S wave is estimated to be 5 · 10^(21) ergs

Seismic moment, stress, and source dimensions for earthquakes in the California-Nevada region

The source mechanism of earthquakes in the California‐Nevada region was studied using surface wave analyses, surface displacement observations in the source region, magnitude determinations, and accurate epicenter locations. Fourier analyses of surface waves from thirteen earthquakes in the Parkfield region have yielded the following relationship between seismic moment, M_0 and Richter magnitude, M_L: log M_0 = 1.4 M_L + 17.0, where 3 < M_L < 6. The following relation between the surface wave envelope parameter AR and seismic moment was obtained: log M_0 = log AR_(300) + 20.1. This relation was used to estimate the seismic moment of 259 additional earthquakes in the western United States. The combined data yield the following relationship between moment and local magnitude: log M_0 = 1.7 M_L + 15.1, where 3 < ML < 6. These data together with the Gutenberg‐Richter energy‐magnitude formula suggest that the average stress multiplied by the seismic efficiency is about 7 bars for small earthquakes at Parkfield and in the Imperial Valley, about 30 bars for small earthquakes near Wheeler Ridge on the White Wolf fault, and over 100 bars for small earthquakes in the Arizona‐Nevada and Laguna Salada (Baja California) regions. Field observations of displacement associated with eight Parkfield shocks, along with estimates of fault area, indicate that fault dimensions similar to the values found earlier for the Imperial earthquake are the rule rather than the exception for small earthquakes along the San Andreas fault. Stress drops appear to be about 10% of the average stress multiplied by the seismic efficiency. The revised curve for the moment versus magnitude further emphasizes that small earthquakes are not important in strain release and indicate that the zone of shear may be about 6 km in vertical extent for the Imperial Valley and even less for oceanic transform faults

Radio-Programm-Controlling: Instrumente, Verfahren und Resultate : Forschungsbericht Radio-Monitoring: Regionaljournal ZH/SH vom 25.- 27. Juni 2003

Die Studie Radio-Programm-Controlling hat das Ziel, ein in Radioredaktionen anwendbares Instrument zu entwickeln, das interene Programmbeobachtung und externes Monitoring koppelt und von redaktionellen Führungskräften zur kontinuierlichen Sendungsbeobachtung und -evaluation (publizistische Leistung) eingesetzt werden kann. Es soll zudem die interne Kritik- und Feedbackkultur fördern und die Redaktionsführung bei der Entwicklung der Programmstrategie unterstützen. Zu diesem Zweck wurde am Institut für Angewandte Medienwissenschaft der Zürcher Hochschule Winterthur (IAM) in Zusammenarbeit mit der Redaktion des Regionaljournals Zürich / Schaffhausen ein Befragungsinstrument entwickelt, das es erlaubt, interne (Programmschaffende) und externe (Hörerschaft) Qualitätsbeurteilungen dreier Sendungen miteinander zu vergleichen. Das Monitoring-System soll es der Redaktion ermöglichen, bezüglich der Beurteilung einzelner Sendungen und Beiträge hinsichtlich vorbestimmter Qualitätskriterien mögliche Unterschiede zwischen der Wahrnehmung der Programmschaffenden und der Hörerschaft zu ermitteln. Das Instrument kann dafür eingesetzt werden, die aus Sicht der Befragten über- bzw. unterdurchschnittlichen Beurteilungen bezüglich eines einzelnen Beitrags zu ermitteln. Der Einsatz des Monitoring-Instrumentes soll es den Redaktions- bzw. Sendungsverantwortlichen ermöglichen, die von ihnen verantworteten Sendungen systematisch und kontinuierlich qualitätsorientiert analysieren zu können. Dem Monitoring-System liegen Fragen bzw. Beurteilungskriterien zugrunde, welche die Programmschaffenden des Regionaljournals ZH/SH selber als Ergebnis mehrerer Gesprächrunden als zentral identifiziert haben. Es wurde zusammen mit den Programmschaffenden ein Fragebogen für die interne und externe Befragung entwickelt. Dieser kam sowohl beim internen als auch beim externen Monitoring zur Anwendung. An der Befragung teilgenommen haben im internen Monitoring 20 Mitarbeiter von DRS 1. Diese von der Redaktionsleitung bestimmten Befragten haben je drei Sendungen (25. / 26. / 27. Juni 2003) beurteilt (es liegen insgesamt 57 Beurteilungen vor). Am externen Monitoring haben 199 Hörerinnen und Hörer teilgenommen, welche mittels Quota-Stichprobeverfahren rekrutiert worden sind

Seismic moment, stress, and source dimensions for earthquakes in the California-Nevada region

The source mechanism of earthquakes in the California‐Nevada region was studied using surface wave analyses, surface displacement observations in the source region, magnitude determinations, and accurate epicenter locations. Fourier analyses of surface waves from thirteen earthquakes in the Parkfield region have yielded the following relationship between seismic moment, M_0 and Richter magnitude, M_L: log M_0 = 1.4 M_L + 17.0, where 3 < M_L < 6. The following relation between the surface wave envelope parameter AR and seismic moment was obtained: log M_0 = log AR_(300) + 20.1. This relation was used to estimate the seismic moment of 259 additional earthquakes in the western United States. The combined data yield the following relationship between moment and local magnitude: log M_0 = 1.7 M_L + 15.1, where 3 < ML < 6. These data together with the Gutenberg‐Richter energy‐magnitude formula suggest that the average stress multiplied by the seismic efficiency is about 7 bars for small earthquakes at Parkfield and in the Imperial Valley, about 30 bars for small earthquakes near Wheeler Ridge on the White Wolf fault, and over 100 bars for small earthquakes in the Arizona‐Nevada and Laguna Salada (Baja California) regions. Field observations of displacement associated with eight Parkfield shocks, along with estimates of fault area, indicate that fault dimensions similar to the values found earlier for the Imperial earthquake are the rule rather than the exception for small earthquakes along the San Andreas fault. Stress drops appear to be about 10% of the average stress multiplied by the seismic efficiency. The revised curve for the moment versus magnitude further emphasizes that small earthquakes are not important in strain release and indicate that the zone of shear may be about 6 km in vertical extent for the Imperial Valley and even less for oceanic transform faults

(Wenn du jung bist, musst du mit anderen Mitteln kämpfen)

In questo rapporto sono contenuti i risultati di uno studio empirico concernente il consumo massmediatico della popolazione ticinese. L’inchiesta è stata condotta dall’«Institut für Angewandte Medienwissenschaft» della «Zürcher Hochschule Winterthur». I dati di questo documento sono presentati nella loro completezza, senza essere accompagnati da un commento critico specifico. Ciò permette al lettore interessato di aver accesso ai risultati dell’inchiesta in maniera trasparente e rispettosa dei criteri di scientificità richiesti dalla ricerca.Dieser Bericht enthält die Ergebnisse einer empirischen Studie zum Massenmedienkonsum der Tessiner Bevölkerung. Die Untersuchung wurde vom Institut für Angewandte Medienwissenschaft der Zürcher Hochschule Winterthur durchgeführt. Die Daten in diesem Dokument werden in ihrer Gesamtheit ohne spezifische kritische Anmerkung dargestellt. Dies ermöglicht dem interessierten Leser einen transparenten und respektvollen Umgang mit den Untersuchungsergebnissen der wissenschaftlichen Forschung