Publications

The simplest index of geomagnetic activity is the range in nT from maximum to minimum value of the field in a given time interval. The hourly range R was recommended by IAGA for use at observatories at latitudes greater than 65??, but was superceded by AE. The most used geomagnetic index K is based on the range of activity in a 3 h interval corrected for the regular daily variation. In...

During 1980 and 1981, the U.S. Geological Survey collected seismic refraction data in the western Mojave Desert (fig. 1). The seismic refraction data extends from north of the Garlock Fault, south through the Mojave Desert, and across the San Andreas Fault into the San Gabriel Mountains. This report describes and documents the recorded data, which was collected over three field sessions...

No abstract available.

No abstract available.

Slip distribution at depth on a fault may be inferred from the deformation observed on the surface. In inverting the surface deformation data to obtain the slip distribution, the Earth is generally approximated by an elastic half‐space. Slip distributions inferred from a half‐space model may contain artifacts, including zones of reversed slip, due solely to effects of layering in the...

A real-time system for issuing warnings of landslides during major storms is being developed for the San Francisco Bay region, California. The system is based on empirical and theoretical relations between rainfall and landslide initiation, geologic determination of areas susceptible to landslides, real-time monitoring of a regional network of telemetering rain gages, and National...

During the first five days of November 1985, a low-pressure system in the Ohio River valley combined with a low-pressure system referred to as Tropical Storm Juan to produce heavy rainfall in the Potomac, James, and Rappahannock River basins. Severe flooding accompanied the rainfall; 43 lives were lost and the flood was estimated to be the most expensive natural disaster of 1985 in the...

More seismological studies of the continental crust and sub‐crustal lithosphere of the United States have been completed in the past four years than at any other similar period, and a continued growth in activity is likely to continue for years to come. Several trends account for this phenomenon. First, the interest in seismic reflection studies generated initially by COCORP results in...

Vertical-incidence reflection profiling has identified several characteristic features of the continental lithosphere including a generally transparent upper crust, a reflective lower crust, reflections from the crust-mantle boundary, and a commonly transparent upper mantle. The underlying physical causes of these characteristic features remain poorly understood. This review summarizes...

In 1981, the U.S. Geological Survey conducted a seismic-refraction experiment in northeastern California designed to study the Klamath Mountains, Cascade Range, Modoc Plateau, and Basin and Range provinces. Key profiles include 135-km-long, north-south lines in the Klamath Mountains and Modoc Plateau provinces and a 260-km-long, east-west line crossing all of the provinces. The seismic...

The past four years have been particularly fruitful for Martian research as the enormous volumes of data collected during the Viking mission became readily available to the general science community, and as reformatting of the remote sensing data into cartographic products made the data more useable. The 1:5,000,000‐scale map series is complete, and 1:2,000,000‐scale controlled mosaics...

No abstract available.