Geology topics

K. L. Johnson

Publications and source records attributed to K. L. Johnson.

4 recordsLinked to original sources

USGS2012

ShakeMap Atlas 2.0: an improved suite of recent historical earthquake ShakeMaps for global hazard analyses and loss model calibration

We introduce the second version of the U.S. Geological Survey ShakeMap Atlas, which is an openly-available compilation of nearly 8,000 ShakeMaps of the most significant global earthquakes between 1973 and 2011. This revision of the Atlas includes: (1) a new version of the ShakeMap software that improves data usage and uncertainty estimations; (2) an updated earthquake source catalogue that includes regional locations and finite fault models; (3) a refined strategy to select prediction and conversion equations based on a new seismotectonic regionalization scheme; and (4) vastly more macroseismic intensity and ground-motion data from regional agencies All these changes make the new Atlas a self-consistent, calibrated ShakeMap catalogue that constitutes an invaluable resource for investigating near-source strong ground-motion, as well as for seismic hazard, scenario, risk, and loss-model development. To this end, the Atlas will provide a hazard base layer for PAGER loss calibration and for the Earthquake Consequences Database within the Global Earthquake Model initiative.

Conference Paper↗

USGS1987

Data on the distribution and abundance of submersed aquatic vegetation in the tidal Potomac River and estuary, Maryland, Virginia, and the District of Columbia, 1986

This report summarizes data on the distribution and abundance of submersed aquatic vegetation collected in the tidal Potomac River and Estuary during 1986. Plant species were identified and dry weight determined for selected sites sampled in spring and fall. The percentage of each plant species was determined in areas of high plant density in the fall. Water quality characteristics measured include temperature, specific conductance, dissolved oxygen, pH, and transparency as indicated by Secchi depth. Maps were made of the distribution of submersed aquatic vegetation based on transect samples and a complete shoreline survey.

District of Columbia;Maryl;Virginia↗

USGS1985

Capacity and sedimentation of Loch Lomond Reservoir, Santa Cruz County, California

A sedimentation study of Loch Lomond Reservoir in Santa Cruz County, California, was begun in 1982 to determine reservoir storage capacity and to establish permanent ranges for future studies. Results of a reservoir survey indicated a total storage capacity of 8,824 acre-ft in 1982. Comparison of thalweg profiles from this survey and a survey done prior to dam construction in 1960 shows that deposition has occurred in the lower reach of the reservoir due to landsliding and in the upper reach due to sediment inflow from Newell Creek.

California↗

USGS1984

Ground-water conditions and well yields in fractured rocks, southwestern Nevada County, California

This report describes the availability of ground water in the southwestern part of Nevada County, and suggests general guidelines for selecting sites for future ground-water development in the study area. Ground water in this area occurs chiefly in fractures in hard pre-Tertiary metavolcanic and plutonic rocks generally above a depth of 215 feet. Some ground water is found at the contact between alluvium or decomposed granite and the underlying hard rock; little is found in alluvium or colluvium. Mean yield is less than 18 gallons per minute. (USGS)

Water-Resources Investigations Report↗