Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Earthquakes & Volcanoes (USGS)”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
USGS1991

Natural disasters and insurance and reinsurance

Great natural disasters, that is, those exceeding the economic capacity of the affected region and requiring national or international assistance, have increased dramatically in number and scope over the past few decades. As the accompanying graph shows, on average, from the 1960's to the 1980's there has been a five-fold increase in frequency of natural disasters, an increase in total economic losses by a factor of 3.3 and a rise of total insured losses by a factor of 5.8

Earthquakes & Volcanoes (USGS)↗
USGS1987

One hundred years of earthquake recording at the University of California

Seismology is a relatively new science, so there is special reason to celebrate the first permanent earthquake observatories in America, set up by the University of California 100 years ago. The best seismographs then available arrived from England in 1887 and were installed at Lick Observatory on Mt.Hamilton and at the Students Astronomical Observatory on the Berkeley campus. The first California earthquake recorded by the Lick instrument was on April 24, 1887. These seismographic stations have functioned continuously from their founding to the present day, with improvements in instruments from time to time as technology advanced. Now they are part of a sesimogrpahic network of 16 stations recording with great completeness both local and distant earthquakes.

Earthquakes & Volcanoes (USGS)↗
USGS1991

On seismological moments and magnitudes

My approach to seismology over the years has always been from the point of view of applied mathematics, as exemplified broadly by the work of the late Sir Harold Jeffreys and Professor K. E. Bullen. Both stresses the development of mathematics in the context of physical systems and of modeling, with an eye always on the side of inference. Seismology provided for them and still provides today the almost perfect paradigm; the problem is the resolution of the detailed consitution of the Earth and its geologically short-term dynamics. The latter part, includes, of course, seismic-risk estimation. The last 20 years have seen the construction of a brilliant theoretical formalism for linear inverse problems in seismology , although, oddly enough, the current popular Earth models do not take account it. It is interesting too that the narrow opinion, prevelent a decade ago, to the effect that the traditional seismic body-wave approaches to structural definition were superceded, has been largely abandoned under today's banner of tomography-as though the Oldham-Jeffreys-Gutenbery inversions were not tomography.

Earthquakes & Volcanoes (USGS)↗
USGS1990

Of parachuting spiders and meat-eating beetles

Scientists have been amazed at the rapid recovery of life that followed the volcanic eruption at Mount St. Helens 10 years ago, but to the uninitiated, the place is still a stark and awesome wasteland. Here and there on the rolling hills of gray volcanic ash around the volcano are clumps of invading fireweed and another pioneer called pearly everlasting. Alder and Willow saplings grow sporadically along the otherwise barren stream courses. Plugs of grass sprout in piles of elk droppings. And deer mic and pocket gophers, the survivialists of the animal world, also have managed to gain foothold.

Washington↗
USGS1990

Will the 1990’s be a decade of increasingly destructive natural disasters?

Today, there is a considerable body of knowledge about natural hazards that laso enables us to devise effective means to limit the damage they cause. Yet, the reality of the situation is that disasters are increasing in number worldwide, and their social and economic impacts are becoming more nad more difficult to hear.

Earthquakes & Volcanoes (USGS)↗
USGS1993

The Klamath Falls, Oregon, earthquakes on September 20, 1993

The strongest earthquake to strike Oregon in more than 50 yrs struck the southern part of the State on September 20, 1993. These shocks, a magnitude 5.9 earthquake at 8:28pm and a magnitude 6.0 earthquake at 10:45pm, were the opening salvo in a swarm of earthquakes that continued for more than three months. During this period, several thousand aftershocks, many strong enough to be felt, were recorded by seismographs. The mainshocks caused light moderate damage at Klamath Falls, a town of about 18,000 residents located only about 20 km east of the epicentral area. Damage included toppled chimneys, cracked masonry, and fallen parapets. Power outages occurred after the strongest shocks. In addition, strong shaking broke water mains, and landslides temporarily blocked highways. the earthquakes also caused two fatalities. A rockfall crushed an automobile, killing a motorist, and an elderly lady had a heart attack. the low population density in the epicentral area- less than five people per sq km- kept the toatl dollar loss to about 7.5 million dollars.

Oregon↗
USGS1993

The danger of collapsing lava domes; lessons for Mount Hood, Oregon

Nestled in the crater of Oregon's majestic Mount Hood volcano is Crater Rock, a prominent feature known to thousands of skiers, climbers, and tourists who journey each year to the famous Timberline Lodge located high on the volcano's south flank. Crater Rock stands about 100m above the sloping crater floor and warm fumaroles along its base emit sulfur gases and a faint steam plume that is sometimes visible from the lodge. What most visitors do not know, however, is that Crater Rock is a volcanic lava dome only 200 years old.

Oregon↗
USGS1987

Earthquakes and groundwater

As part of the U.S Geological Survey prediction experiment at Parkfield along the San Andreas fault in California, a network of water wells is being monitored. this network consists of wells that are situated at seven sites that were drilled by Geological Survey for the express prupose of monitoring water levels. These wells have turned out to be very sensitive volume strain meters. The scientific rationale for the wells as strain meters is explained in some detail below.

Earthquakes & Volcanoes (USGS)↗
USGS1992

Preliminary damage and intensity survey

A major earthquake struck the Mojave Desert region in southern California at about 5 a.m. local time on June 28th, 1992. Seismologists located the epicenter of the magnitude 7.6 (Ms) earthquake 5-10km southwest of Landers, a small community about 150km east of Los Angeles. the earthquake shook a wide area of southern California, southern Nevada, western Arizona, and extreme northwest Mexico. High-rise buildings swayed in cities as far north as Boise, Idaho, and as far east as Albuquerque, New Mexico, and Denver, Colorado. Standing waves called seiches disturbed the surface of lakes and bays as far away as Washington State and the Gulf Coast of Texas. In United States, the Landers shock was felt over a contiguous land area approximately 103.600km2. Approximately 3 hrs after the Landers earthquake, a magntude 6.7 (Ms) aftershock struck an area near Big Bear Lake, California, less than 50 km from the main-shcok epicenter. Within its epicentral area this afterhoskc caused consideralbe damage.

California↗
USGS1990

Geology and land use

Geologists' eyes are trained to find and trace such natural landmarks as flood plains, landslide scars, retreating shoreline bluffs, or surface traces of active earthquake faults. more and more often, in developing areas, we find these obvious signs of trouble being erased by urban development. A geological hazard concealed by landscaping or hosing is fully as dangerous as when it is visible. The geologic limitations for building sites of some areas can be overcome, in part, by skilled engineering and expensive construction practices. But the costs can be prohibitively high, and the solutions are not always completely effective. In "earthquake country," history has shown that costs are highest and risk factors most uncertain in a few easily recognized settings: unstable hill sloped, land at the edge of rapidly eroding sea cliffs, lowlands underlain by saturated estuarine mud of ill, and areas near faults capable of producing magnitude 7 or greater earthquakes. Safety immediately after an earthquake is also a concern in these places, for extreme damage and ground distortion may impede or prevent timely access by emergency equipment.

Earthquakes & Volcanoes (USGS)↗
USGS1992

The National Landslide Information Center; data to reduce landslide damage

Almost every day a landslide disasters occurs somewhere in the world. Nearly any time there is heavy rainfall, an earthquake, a volcanic eruption, strong wave action on a shoreline, or some ill-considered alteration of sloping land by humans, landslides occur. In a world of persistent and increasing construction on and occupation of hillslopes, canyons, and coastal bluffs, landslides are exacting an inexorable toll of human life and economic loss. In the 1980's, massive landslides disasters occurred throughout the world, many in regions where such disasters were historically unprecedented, or where their potential was forgotten or disregarded. by present generations. In some cases, large populations had moved onto unstable lands before renewed landslide activity. For example, the San Francisco Bay region in population between 1955 and 1982, and much of the new development occurred on hillsides and in canyons. Major rainstorms in both 1955 and 1982 produced abundant landslides throughout the region, but the landslides in 1982 proved much more devastating than those in 1955 because of the increased population density on sloping ground. Similar situations persist in many other population centers surrounded by hills and mountains, such as Rio de Janeiro, Hong Kong, and Los Angeles.

Earthquakes & Volcanoes (USGS)↗
USGS1987

A visit to Stromboli, lighthouse of the Mediterranean

About daybreak of the next morning, the perfect cone-shaped outline of Stromboli appeared on the horizon. No "red" glare could be seen, but a prominent column of white vapor was rising from the crater, and at infrequent emitted. As the boat steamed around the edge of Stromboli, the big "scar' on the slope, known as Sciara del Fuoco, stood out prominently. This remarkable feature, with a slope of 35 degrees and a width of about three-quarters of a mile, is like a tremendous talus slope and extends from the crater to the sea, a distance of about 4,000 feet. Much of the erupted material, including lava flows ejected from the crater, lands on the Sciara del Fuoco and rolls directly into the sea. The origin of the Sciara del Fuoco is uncertain, but it appears to represent a great depression formed by an eruption which destroyed one side of the cone. The accumulation of debris in the depression has built up the present talus-like slope. The crater of Stromboli is on a terrace at the top of the Sciara del Fuoco, about 600 feet below the summit peak.

Stromboli↗
USGS1987

Volcanic processes in the solar system

Eruptions of ammonia, water, and sulfur. These have become some of the concerns of planetary volcanologists as they try to understand volcanic processes on other planetary bodies. As exploration of the Solar System has continues, we have been confronted with more and more exotic forms of volcanism and have come to realize that the types of volcanic activity observed on Earth represent only a fraction of the array of volcanic phenomena that are possible. Some volcanic features of other planets have close terrestrial counterparts and appear to have been formed by similar mechanisms and from similar magmas to those on the Earth. but other features are totally different and appear to have been formed from materials that are not normally associated with volcanism on Earth.

Earthquakes & Volcanoes (USGS)↗
USGS1990

Present state of studies of volcanic risk in Colombia

Because of the reactivation of Nevado del Ruiz volcano in the last days of 1984, we began studies whose purpose was directed toward the identification of hte risks that accompanied such volcanic activity. As a result of these investigations there appeared a preliminary map of volcanic risk in Octoer 7, 1985, the first map of its kind in Colombia

Earthquakes & Volcanoes (USGS)↗