Earthquake Potential Along the Hayward Fault, California

The Loma Prieta event probably marks a renewed period of major seismic activity in the San Francisco Bay Area. Particularly ominous is the historic record of major events a few years apart on opposite sides of the Bay in 1836 (N. Hayward fault) and 1838 (N. Peninsula, San Andreas fault) and 1865 (Loma Prieta segment, San Andreas fault), and 1868 (S. Hayward fault) (Figure 1). Recent preliminary measurements of the Holocene geologic slip rate of the Hayward fault are as much as 9 mm/yr (Lienkaemper and others 1989) - about 80% greater than the first Holocene measurements determined as recently as 1987 (Borchardt and others 1987). Aseismic slip, as measured from monuments and offsets of cultural features, varies along the fault from 3 to 9 mm/yr and averages 5 mm/yr (Lienkaemper and others 1990). Although the earthquake potential calculated from such data are greatly affected by initial assumptions, the extremes are instructive: Method I assumes that the fault is freely slipping along the entire fault plane and that, until aseismic slip ceases, no major events are possible. Method II assumes that aseismic slip occurs throughout the 10-km deep seismogenic zone, but that strain continues to build at the deficit rate about 4 mm/yr and strain builds at slightly less than the geologic rate (9 mm/yr). Assuming that 1.1 to 1.2 m of displacement occurs at depth during M 6. 8 events (Slemmons and Chung, 1982), calculated recurrences range from 120 to 300 years. Thus, in view of the time elapsed since the two previous events (123 and 155 years), we have entered the earthquake window for the Hayward fault. The new geologic rate has increased the estimates of 30 year probabilities for major events from 20% to 28% on the north half of the fault and from 20% to 23% on the southern half (compare WGCEP of 1988 and 1990)

Mineralogy and trace-element composition of ash and pumice soils in the Pacific Northwest of the United States

Published May 1969. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

Quasi-periodic fractal patterns in geomagnetic reversals, geological activity, and astronomical events

AbstractThe cause of geomagnetic reversals remains a geological mystery. With the availability of improved paleomagnetic databases in the past three years, a reexamination of possible periodicity in the geomagnetic reversal rate seems warranted. Previous reports of cyclicity in the reversal rate, along with the recent discovery of harmonic cycles in a variety of natural events, sparked our interest in reevaluating possible patterns in the reversal rate. Here, we focus on geomagnetic periodicity, but also analyze paleointensity, zircon formation, star formation, quasar formation, supernova, and gamma ray burst records to determine if patterns that occur in other types of data have similar periodicity. If so, then the degree of synchronization will indicate likely causal relationships with geomagnetic reversals. To achieve that goal, newly available time-series records from these disciplines were tested for cyclicity by using spectral analysis and time-lagged cross-correlation techniques. The results showed evidence of period-tripled cycles of 30.44, 91.33, 274, 822, and 2466 million years, corresponding to the periodicity from a new Universal Cycle model. Based on the results, a fractal model of the universe is hypothesized in which sub-electron fractal matter acts as a dynamic medium for large-scale waves that cause the cycles in astronomical and geological processes. According to this hypothesis, the medium of sub-electron fractal matter periodically compresses and decompresses according to the standard laws for mechanical waves. Consequently, the compressions contribute to high-pressure environments and vice versa for the decompressions, which are hypothesized to cause the instabilities that lead to episodic astronomical and geological events

Academic Journals Plagued by Bogus Impact Factors

The current status of academic publishing is worrying. Cybercriminals are now targeting academic audiences, making it necessary to inform both editors and authors about such issues. The latest involves bogus impact factors, which are challenging scholarly publishing. Legitimate impact factors are used by authors and editors to get a general idea of the audience, if any, for a particular piece or journal. The bogus metrics only add confusion in support of the cybercrimes of their initiators. In this paper, we discuss bogus impact factors, victim countries, and try to clarify the phenomena for both authors and editors

Statistical analyses of Global U-Pb Database 2017

The method of obtaining zircon samples affects estimation of the global U-Pb age distribution. Researchers typically collect zircons via convenience sampling and cluster sampling. When using these techniques, weight adjustments proportional to the areas of the sampled regions improve upon unweighted estimates. Here, grid-area and modern sediment methods are used to weight the samples from a new database of 418,967 U-Pb ages. Preliminary tests involve two age models. Model-1 uses the most precise U-Pb ages as the best ages. Model-2 uses the 206Pb/238U age as the best age if it is less than a 1000 Ma cutoff, otherwise it uses the 207Pb/206Pb age as the best age. A correlation analysis between the Model-1 and Model-2 ages indicates nearly identical distributions for both models. However, after applying acceptance criteria to include only the most precise analyses with minimal discordance, a histogram of the rejected samples shows excessive rejection of the Model-2 analyses around the 1000 Ma cutoff point. Because of the excessive rejection rate for Model-2, we select Model-1 as the preferred model. After eliminating all rejected samples, the remaining analyses use only Model-1 ages for five rock-type subsets of the database: igneous, meta-igneous, sedimentary, meta-sedimentary, and modern sediments. Next, time-series plots, cross-correlation analyses, and spectral analyses determine the degree of alignment among the time-series and their periodicity. For all rock types, the U-Pb age distributions are similar for ages older than 500 Ma, but align poorly for ages younger than 500 Ma. The similarities (>500 Ma) and differences (<500 Ma) highlight how reductionism from a detailed database enhances understanding of time-dependent sequences, such as erosion, detrital transport mechanisms, lithification, and metamorphism. Time-series analyses and spectral analyses of the age distributions predominantly indicate a synchronous period-tripling sequence of ∼91-Myr, ∼273-Myr, and ∼819-Myr among the various rock types