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Elizabeth M. Colvard

Publications and source records attributed to Elizabeth M. Colvard.

6 recordsLinked to original sources

U.S. Geological Survey Menlo Park campus: Self-guided tour

The U.S. Geological Survey (USGS), established by an act of Congress in 1879, is the Nation's largest natural science and civilian mapping agency. The USGS works in cooperation with more than 2,000 organizations across the country to provide reliable, impartial scientific information. This information is used to minimize the loss of life and property from natural disasters, safeguard the Nation's natural resources, and enhance quality of life through careful monitoring of water, biological, energy, and mineral resources.

California

Facing the great disaster : How the men and women of the U.S. Geological Survey responded to the 1906 "San Francisco Earthquake"

It was the most devastating earthquake in California’s history. At 5:12 a.m. on April 18, 1906, the ground under the San Francisco Bay Area shook violently for more than 40 seconds. The magnitude 7.8 earthquake created a rupture along nearly 300 miles of the San Andreas Fault and was felt from southern Oregon to Los Angeles. Because the earthquake’s epicenter was just offshore from San Francisco, the impact on that city was catastrophic. Fragments of broken houses and buildings tumbled into the streets. The pipeline carrying water into the city was severed; fires triggered by broken gas mains raged out of control for 3 days. An area of almost 5 square miles in the heart of the city was destroyed by shaking and fire, and earthquake damage was widespread elsewhere. At least 3,000 people were killed, and 225,000 were left homeless. Drinking water, food, and supplies quickly became scarce. In 1906, the only permanent U.S. Geological Survey (USGS) office in California was the Pacific Division topographic mapping office in Sacramento, 70 miles up the Sacramento River from San Francisco Bay. The office had been established just 3 years earlier and was the only USGS office ever created for the sole function of topographic mapping. At the time of the earthquake, many USGS topographers were in Sacramento preparing for a summer of field work. Although moderate shaking was felt in Sacramento, then a town of about 30,000 people, detailed information about the earthquake was slow to reach the residents there. USGS topographic engineer George R. Davis, not knowing the full extent of the damage, was fearful that his 62-year-old father Edward Davis in San Francisco was caught up in the devastation. George therefore left Sacramento on the first train bound for the San Francisco Bay area. “He was very worried. The phones were down and he wasn’t sure whether or not the hotel his father was living in was damaged,” said George Davis’s daughter Anna (Davis) Rogers, then an octogenarian, in a 2005 interview. Recalling the stories she heard of these events while growing up, Anna added, “Fortunately [the hotel] hadn’t fallen down.” George Davis, a tall man with a quiet demeanor and a dry wit, was accompanied to San Francisco by fellow USGS topographer Clarence L. Nelson. Both were 29 years old and in excellent physical condition after a year spent mapping the Mount Whitney quadrangle, which includes some of the most rugged terrain in the conterminous United States. On their arrival in San Francisco, the pair was fortunate to find the elder Davis unharmed at the hotel where he had been living. Nelson—handsome, athletic, and artistic—had brought his camera in order to get photographs while things were still “hot” and began taking what were to become a memorable set of images. The three men wandered through San Francisco all night and through the following morning, moving from one dramatic scene to the next. Nelson captured the horse-mounted “dynamite squad,” soldiers marching on Van Ness Avenue, and a rare scene of two horsedrawn fire engines with one engine drawing water from a cistern on Union Street. One ironic photograph shows refugees making their way through rubble-filled streets in the direction of a wrecked City Hall. Flames from the burning heart of the city shone brightly against the darkness, and Nelson captured the surreal glow in several of his photographs, including one of Union Square with the Breuners building burning in the background.

General Information Product

Invisible CO2 gas killing trees at Mammoth Mountain, California

Since 1980, scientists have monitored geologic unrest in Long Valley Caldera and at adjacent Mammoth Mountain, California. After a persistent swarm of earthquakes beneath Mammoth Mountain in 1989, geologists discovered that large volumes of carbon dioxide (CO2 ) gas were seeping from beneath this volcano. This gas is killing trees on the mountain and also can be a danger to people. The U.S. Geological Survey (USGS) continues to study the CO2 emissions to help protect the public from this invisible potential hazard.

Fact Sheet

Abrupt physical and chemical changes during 1992-1999, Anderson Springs, SE Geyser Geothermal Field, California

The Anderson Springs area is located about 90 miles (145 kilometers) north of San Francisco, California, in the southwestern part of Lake County. The area was first developed in the late 1800s as a health resort, which was active until the 1930s. Patrons drank a variety of cool to hot mineral waters from improved springs, swam in various baths and pools, and hiked in the rugged hills flanking Anderson Creek and its tributaries. In the bluffs to the south of the resort were four small mercury mines of the eastern Mayacmas quicksilver district. About 1,260 flasks of mercury were produced from these mines between 1909 and 1943. By the early 1970s, the higher ridges south and west of Anderson Springs became part of the southeast sector of the greater Geysers geothermal field. Today, several electric power plants are built on these ridges, producing energy from a vapor-dominated 240 °C reservoir. Only the main hot spring at Anderson Springs has maintained a recognizable identity since the 1930s. The hot spring is actually a cluster of seeps and springs that issue from a small fault in a ravine southwest of Anderson Creek. Published and unpublished records show that the maximum temperature (Tm) of this cluster fell gradually from 63°C in 1889 to 48°C in 1992. However, Tm of the cluster climbed to 77°C in 1995 and neared boiling (98°C) in 1998. A new cluster of boiling vents and small fumaroles (Tm = 99.3°C) formed in 1998 about 30 m north of the old spring cluster. Several evergreen trees on steep slopes immediately above these vents apparently were killed by the new activity. Thermal waters at Anderson Hot Springs are mostly composed of near-surface ground waters with some added gases and condensed steam from The Geysers geothermal system. Compared to gas samples from Southeast Geysers wells, the hot spring gases are higher in CO 2 and lower in H 2 S and NH 3 . As the springs increased in temperature, however, the gas composition became more like the mean composition of steam discharges from the Southeast Geysers. The hot spring waters are low in ions of Cl, B, and Li, but relatively high in HCO 3 , SO 4 and NH 4 . The stable-isotope compositions (deuterium and oxygen-18) of these waters plot near the global meteoric water line. Geochemical data through time reveal apparent maxima in the concentrations of SO 4 , Fe, and Mn in 1991 to 1992, before the cluster became hotter. The black-to-gray deposits from the new spring cluster are rich in pyrite and contain anomalous metals. About one-half mile to the east of the hot springs, mineralized water discharges intermittently from an old adit of the Schwartz (Anderson) mine, and enters a tributary of Anderson Creek. This drainage increased substantially in July 1998, and a slurry of mine water and precipitates were transported down the tributary and into Anderson Creek. In December 1998, the adit water was 22°C, and had a chemical composition that was similar to spring waters that once discharged in the ravines surrounding the old Anderson Springs resort. The cause for the abrupt changes that have occurred in thermal features at Anderson Springs is still not resolved. One possibility is that these changes are a response to withdrawal of steam from The Geysers geothermal field over more than 20 years of production. Pressure declines in the geothermal reservoir may have caused a "drying out" of the overlying condensation zone. Induced boiling in this zone and upflow of deep steam to shallower depths would cause heating and vaporization of shallow ground waters. In addition, earthquakes occurring in the vicinity of Anderson Springs have increased significantly after nearby geothermal power plants began operation. These earthquakes may have enhanced surface discharge of thermal fluids along fractures and faults.

California

Measurements of heat and mass flow from thermal areas in Lassen Volcanic National Park, California, 1984-93

Rates of heat loss from eight steam-heated thermal areas and one conductively heated thermal area in Lassen Volcanic National Park have been determined from measurements made during the period 1984-93. Total heat discharge at the steam-heated areas is assumed proportional to the rate of steam upflow from underlying reservoirs. The dominant mode of heat loss differs among the areas studied; at Bumpass Hell and Boiling Springs Lake evaporation from water surfaces dominates, whereas at Devils Kitchen and Little Hot Springs Valley most of the heat is lost by advection in streams. Heat loss from furnaroles, which discharge at temperatures of 93 157°C depending on the area, accounts for less than 30 percent of the total heat loss for all but the smallest thermal areas. Estimates of total heat loss from the eight steam-heated areas range from about 30 megawatts at Bumpass Hell and Boiling Springs Lake to less than 2 megawatts at Terminal Geyser, Pilot Pinnacle and Lassen Peak, and total about 120 megawatts. The corresponding rate of steam upflow required to supply this total heat loss is approximately 40 kilograms per second, with about half providing heat input to the five thermal areas situated on the flanks of Lassen Peak and the remainder supplying heat to thermal areas situated to the southeast of Lassen Peak along or near Hot Springs Creek. For the most part, heat-loss measurements were made during late summer and fall when streamflows were relatively low. At each thermal area, rates of streamflow and advective heat loss are greatest in the spring and early summer, reflecting depletion of stored heat by infiltrating cold water. Such seasonal variations, along with variations due to errors in our heat-loss determinations, result in uncertainties of approximately ± 20 percent in our estimates of total heat loss and steam upflow at all the Park's thermal areas.

California