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Robert E. Wallace

Publications and source records attributed to Robert E. Wallace.

10 recordsLinked to original sources
USGS2014

A variable, circular‐arc rule; An aid in constructing stereographic projections

A drafting instrument which provides a ruling edge for drawing arcs of circles the radii of which are unusually long is described. A complete range of arcs of different curvature, within the limits prescribed by the construction of the instrument, are obtainable. This instrument was developed originally to allow accurate construction of circular arcs of very low curvature, which are difficult or impossible to draw with an ordinary compass, in constructing stereographic projections . It is apparent, of course, that numerous other applications are possible. To satisfy the authors' needs, a relatively small model was constructed, but the same general construction could be used in larger models.

Eos, Transactions, American Geophysical Union↗
USGS1993

The San Andreas Fault

The presence of the San Andreas fault was brought dramatically to world attention on April 18, 1906, when sudden displacement along the fault produced the great San Francisco earthquake and fire. This earthquake, however, was but one of many that have resulted from episodic displacement along the fault throughout its life of about 15-20 million years.

California↗
USGS1992

The San Andreas Fault

Explore the source record for details and available documents.

General Interest Publication↗
USGS1991

Ground-squirrel mounds and related patterned ground along the San Andreas Fault in Central California

Extensive areas of mound topography and related patterned ground, apparently derived from the mounds of the California Ground Squirrel (Spermophilus beecheyi beecheyi), are in central California. The relation of patterned ground to the San Andreas fault west of Bakersfield may provide insight into the timing of deformation along the fault as well as the history of ground squirrels. Mound topography appears to have evolved through several stages from scattered mounds currently being constructed on newly deposited alluvial surfaces, to saturation of areas by mounds, followed by coalescence, elongation and lineation of the mounds. Elongation, coalescence and modification of the mounds has been primarily by wind, but to a lesser extent by drainage and solifluction. A time frame including ages of 4,000, 10,500, 29,000, and 73,000 years BP is derived by relating the patterns to slip on the San Andreas fault. Further relating of the patterns to faulting, tilting, and warping may illuminate details of the rates and history of deformation. Similarly, relating the patterns to the history of ground squirrel activity may help answer such problems as rates of dispersal and limits on population density.

Open-File Report↗
USGS1970

Earthquake recurrence intervals on the San Andreas fault

Possible recurrence intervals between earth- quakes of different magnitude that may be generated along the San Andreas fault are derived by relating long-term offset rates since mid-Tertiary time, displacements, and lengths of breaks recorded for historic earthquakes, and tectonic creep rates. The recurrence interval for earthquakes of different magnitude at a given point on the fault is believed to follow the relation: (1) R x = D / (S - C) where: R x = recurrence interval at a point on the fault, D = displacement accompanying an earthquake of given magnitude (related empirically to Richter magnitude), S = long-term strain rate (from offset of geo- logic units), C = tectonic creep rate. The recurrence interval for earthquakes of different magnitudes for the total length of the fault is then derived by weighting equation (1) according to the number of break lengths in the total length as follows: (2) R t = DL / (S - C)L t where: R t = recurrence interval for entire fault, L = length of break (related empirically to Richter magnitude), L t = total length of fault. Tectonic creep is believed to be related to Richter magnitude, for example, small for segments of the fault characterized by earthquakes of large magnitude, and large for segments characterized by small earthquakes; and equations (1) and (2) can be weighted according to this relationship

California↗
USGS1968

Earthquake of August 19, 1966, Varto Area, eastern Turkey

The earthquake of August 19, 1966, centered near Varto in eastern Turkey. It occurred at 12:22:09.6 G. M. T. and had a Richter magnitude of about 7. Intensities reached IX. Reportedly, 2,529 people were killed, 1,500 injured, and 19,013 buildings were demolished or heavily damaged. Surface fractures in three parallel fracture zones trending N65-70°W display both right-lateral strike slip and extension normal to the fractures. The trend and sense of displacement relate the fracturing to the North Anatolia fault system. Examples of geologic factors influencing damage include: (1) degree of saturation of the alluvium, (2) proximity to landslides, and (3) relation to surface faulting.

Near Varto in eastern Turkey↗
USGS1965

Geology of the Coeur d'Alene district, Shoshone County, Idaho

The Coeur d'Alene district, near the base of the northern panhandle of Idaho, is one of the world's larger lead- zinc and silver-producing areas. The greater part of the dis~rict i~ included within five map areas, from east to west the Pottsville, Mullan, Wallace, Kellogg, and Smelterville, which were geologically mapped during this study. These quadrangles encompass an area about 26 miles long in an east-west direction and about 9 miles wide. The district lies wholly within the Coeur d'Alene Mountains, the part of the Bitterroot Range that is drained by the Coeur d'Alene River. The Bitterroot Range is a rugged, deeply dissected mountain mass which extends on both sides of the Idaho-Montana boundary for more than 200 miles and is a part of the Northern Rocky Mountains; within the district the range has a relief of 3,000-4,000 feet. The westward-flowing South Fork of the Coeur d'Alene River bisects the district, and roads along this river and its major tributaries generally provide easy access to the communities and many mines.

Idaho↗