Search

Studies the stratal geometry and sedimentary facies in the Ridge basin in southern California. Ridge basin as a classic `strike-slip' basin; Subsurface basin geometry based on seismic data.

Examines the effect of the 1994 Northridge Earthquake on geotechnical structures of the Van Norman Complex, the Los Angeles Reservoir and the Power Plant Tailrace in Los Angeles, California. Background on the reservoirs; Tectonic movement; Cracking of asphalt lining; Field observations on settlement, ground cracking and sand boils.

Focuses on a compilation that addresses the questions about the origin and tectonic evolution of the Great Valley and Coast Range ophiolites in California. Tectonic and geologic setting of the area; Thickness of Great Valley ophiolite and possible inclusion of Oceanic mantle as well as oceanic crust; Structural variations along the Great Valley.

The article presents a study which examines the history of tectonics, volcanism, and stratigraphy of the northern San Francisco Bay region in California. It states that the thickness of sedimentary and volcanic deposits and three-dimensional geometry of fault-controlled basins were estimated and inferred through gravity data. It mentions that the hydrogeologic system were reassessed through three-dimensional analysis of litholgic and stratigraphic data from water wells.

Gives information on research findings of why the San Andreas Fault is weak. What geochemists have found; Comments from Mack Kennedy, a member of the Earth Sciences division of the Ernest Orlando Lawrence Berkeley National Laboratory; Description of two models that explains the origin of high pressure fluids in fault zones.

The author offers a response to a commentary made on their study on slip rate discrepancies in the eastern California shear zone. Topics discussed include factor affecting the degree to which wholesale clockwise rotation of the region contributes to the geologic-geodetic discrepancy, advantages of their geodetic analysis using block modeling, and factors that may influence estimated slip rates and limit the ability of the geodetic data to resolve left-lateral slip on the Garlock fault.

The article discusses a study by E. L. Evans and colleagues on the geodetic and geologic estimate of slip rate discrepancy on the Garlock fault (GF) in the eastern California shear zone (ECSZ). Topics covered include comparison of the geodetic and geologic estimate of the slip rate on the GF, dextral shear in the ECSZ, and reason that paleomagnetic evidence for rotation is lacking for the GF.

The article discusses the topographic evolution and the uplift of Sierra Nevada in California. According to the interpretation of the geologists, the evolution of topography of the Sierra Nevada and Great Basin represented the relationship between topography and tectonics. It highlights a study that examines the relationship between hydration water in volcanic glass and the uplift of Sierra Madre.

This article discusses how research facilitating the increased understanding of slow earthquakes may provide a more complete understanding of the processes associated with ordinary earthquakes. The term slow earthquake encompasses a number of phenomena, including slow-slip events and very-low-frequency earthquakes. Slow earthquakes are typically accompanied by deep tremor and occur as shear slip events of tectonic plates. These tremors can be sensitive to small variations in geophysical stress, as they have been triggered by lunar tides. Monitoring of tremor phenomena via seismic stations is discussed, and peculiarities associated with the San Andreas Fault are elucidated.

The article focuses on the different geological patterns of earthquakes. Based on the paleoseismological studies at Pallet Creek on the San Andreas fault in California, researchers pointed out the Earth's crust has many unknowns at depths which cannot be observed directly. The establishment of the Southern California Earthquake Center (SCEC) was taken into account. Key information about the eastern California shear zone (ECSZ) in Mojave Desert is further presented including its fault displacement and plate motion.

The article focuses on the study headed by Sue Cashman concerning the rock deformation of unconsolidated and nolithified deposits. This assesses the factors that inhibit the deformation of the deposits, how these materials in the near-surface regime deforms and how the impact of this deformation may be felt in a variety of settings. The study primarily examines the exhumed fault-related rocks along the San Andreas fault and other faults for over 70 years, highlighting on the exhumed fault rock in bedrock. Moreover, it measures the processes at seismogenic depths where seismic energy is radiated. It also addresses two emerging issues such as the deformation in faults at the surface and the deformation process in poorly lithified deposits prior to burial and diagenesis.

An interview with seismologist Amanda Thomas is presented. Thomas' team at the University of California, Berkeley said to have reported that non-volcanic tremors experienced in San Andreas fault in California is due, in part, to the small stresses induced by tides. According to Thomas, such findings could be beneficial in understanding the how things work at the roots of the faults.

Projects to drill into and recover samples from active faults are progressing in two widely separated locations: off the coast of Japan and in California. [ABSTRACT FROM AUTHOR]

The article reports on the retrieval and examination of rocks taken from an active fault in San Andreas Fault in California. According to scientists, the rocks will be dissected and examined as to how and why faults rupture in quakes. The drilling for the San Andreas Fault Observatory at Depth (SAFOD) began in 2004 and retrieved 44 meters of rock core and is said to be worth $24.6 million, funded by the National Science Foundation. Drillers found that the rock contains slippery mineral talc and bits of serpentine. The organization is unable to continue its project due to lack of funding.

More than 50% of the igneous blocks from mélanges of the Franciscan subduction complex in northernmost California and from the equivalent Dothan Formation of southwestern Oregon are more silica-rich than basalt, and some contain supra-subduction zone geochemical signatures such as elevated Th/Ta ratios. In contrast, blocks from more southerly parts of the Franciscan mélange belt are more commonly mid-ocean ridge and ocean island/seamount basalts. The data indicate a northsouth variation in the block population, due to differences in source terrane, or in the processes that provided the blocks and transported them into the mélange, or both. We suggest that, in the northern Franciscan, a relatively greater fraction of igneous mélange blocks was emplaced by block slumping from the forearc crust into the trench than was the case to the south. [ABSTRACT FROM AUTHOR]

This article reports that almost 12,000 earth and planetary scientists of every stripe met from December 5-9, in California, to discuss topics as varied as the inner workings of the San Andreas fault and ancient muck on Mars. Drillers have punched kilometers down through the San Andreas fault for the first time. A first glance at this "natural earthquake machine" reveals that the fault is relatively weak but not what weakened it, researchers reported at the meeting. In their quest to understand how quakes get started and why almost all fizzle out, investigators will drill straight through the heart of San Andreas quakes as they build the San Andreas Fault Observatory at Depth (SAFOD). The SAFOD drill bit broke through the fault zone in central California last summer, just north of last year's moderate Parkfield earthquake. Drillers were extending the hole begun west of the fault by bending the hole toward the east and through the fault at a depth of almost 3 kilometers, close to a 100-meter patch on the fault that was breaking every 2 years in magnitude-2 quakes. SAFOD workers had two ways to get at fault stress.