Search USGS⌕ Search

SEARCH · Search USGS

Results for “Earthquake Information Bulletin (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 163 records · Page 9Linked to original sources
USGS1983

Seismological programs in Costa Rica

At the beginning of the 1970's, a series of programs in seismology were initiated by different Costa Rican institutions, and some of these programs are still in the process of development. The institutions are Insituto Costaricense de Electricidad (ICE)- The Costa Rica Institute of Electricity La Universidad Nacional Autonoma (UNA)- The National Autonomous University and La Universidad de Costa Rica (UCR)- The University of Costa Rica.

Earthquake Information Bulletin (USGS)↗
USGS1981

The seismicity of Ethiopia; active plate tectonics

"But I tell you, when you look at the way the pieces of the northeastern portion of the African continent seem to fit together, separated by a narrow gulf, you could almost make a believer [in continental drift] of anybody" Astronaut Harrison Schmidt, on the view from Apollo 17. Ethiopia, descended from the semimythical Kingdom of Punt, lies at the strategic intersection of Schmidt's jigsaw puzzle where the Red Sea, Gulf of Aden, and the African Rift System meet. Because of geologically recent uplift combined with rapid downcutting erosion by rivers, notably the Blue Nile (Abbay), Ethiopia is the most mountainous country in Africa. It is also the most volcanically active, while its historical seismicity matches that of the midocean ridges. And, in a sense, Ethiopia is host to an evoloving ocean ridge system.

Earthquake Information Bulletin (USGS)↗
USGS1976

Earthquake at 40 feet

The earthquake that struck the island of Guam on November 1, 1975, at 11:17 a.m had many unique aspects-not the least of which was the experience of an earthquake of 6.25 Richter magnitude while at 40 feet. My wife Bonnie, a fellow diver, Greg Guzman, and I were diving at Gabgab Beach in teh outer harbor of Apra Harbor, engaged in underwater phoyography when the earthquake struck.

Earthquake Information Bulletin (USGS)↗
USGS1980

Tremors from earthquakes and blasting in the Powder River basin of Wyoming and Montana

Coal in the Powder River Basin of Wyoming and Montana (fig. 1) is greatly in demand. It can be economically mined from the surface, and the land is much easier to reclaim than land above underground mines that has been damaged by subsidence or by underground fires. Exploitation of the vast coals resources in the basin has caused a rapid influx of population into the area and an associated increase in building construction. The activity has also generated concern about possible regulation of development. With these facts in mind, the U.S Geological Survey has been investigating the geologic implications of development in the Powder River Basin. One area of study has been the effect of earth tremors caused by blasting in the large coal surface mines or by naturally occurring earthquakes. The basin proper was classified by Algermissen and Perkins (1976) as belonging to a region of low seismic risk. Naturally occurring earthquakes are, therefore, mainly of scientific interest, unless of course there was an isolated event that occurred near a populated area or a surface mine. We are not aware of any damage to people or to property caused by blasting in the coal surface mines even though thousands of tons of explosives are detonated each year in the basin. The maximum weight of an individual explosive charge and the time interval between blasts are regulated so that any nearby structures will not be damaged or the residents disturbed. Blasting, nevertheless, does produce seismic tremors that can be recorded over 200 kilometers away. In addition, at one mine, some very low order aftershocks were recorded relatively close to the source within 2 hours after blasting.

Montana; Wyoming↗
USGS1984

Old seismographs still in operation in Northern California

Felt earthquakes are frequent on the Cape Mendocino end of the northern San Andreas fault in Humboldt County, California. For this reason a Bosch-Omori seismograph was installed by Horace Winslow of the U.S Coast and Geodetic Survey in teh old city jail in Ferndale as early as 1932. In 1981 the seismograph was moved to the Ferndale Museum where it is monitored now by James Scalvini. Data from the seismograph are sent to the Survey's National Earthquake Information Service in Golden, Colorado.

Earthquake Information Bulletin (USGS)↗
USGS1977

Evolution of Seismic Geyser, Yellowstone National Park

The most significant event that has affected the geyser basins of Yellowstone National Park since its discovery was the Hebgen Lake earthquake, which occurred at 11:37 PM on August 17, 1959, with a Richter magnitude of 7.1. The epicenter of this earthquake was just west of the park, about 48 km northwest of the Upper Geyser Basin. No earthquake of comparable intensity had jarred the geyser basins in historic times. More hydrothermal changes occurred in response to this disturbance than during the previous 90 years of the park's history. During the first few days after the earthquake, a reconnaissance was made of most of the thermal features in the Firehole River geyser basins (fig. 1). Early results showed that at least 289 springs had erupted as geysers, and, of these, 160 were springs with no previous record of eruption (Marler, 1964). Some previously obscure springs had erupted very powerfully, and large pieces of sinter were strewn about their craters.

Wyoming↗
USGS1984

On the front lines in Coalinga

I have often been asked, "As a city manager, what is the first thing you do in an earthquake?" I generally say, "Look up, something heavy might be falling on you. Actually, the first step is to declare an emergency. The city council can ratify it later. The declaration is in your emergency preparedness plan, if you can find it. Mine was under a pile of debris; but after, I turned it up, I located an old declaration from a flood disaster and inserted the word "earthquake" wherever I found the word "flood." The declaration is necessary to give the city some protection from liability, which unfortunately, it will need.

California↗
USGS1976

Monitoring Mount Baker Volcano

Hisotrically active volcanoes in the conterminous United States are restricted to the Cascade Range and extend to the Cascade Range and extend from Mount Baker near the Canadian border to Lassen Peak in northern California. Since 1800 A.D, most eruptive activity has been on a relatively small scale and has not caused loss of life or significant property damage. However, future volcanism predictably will have more serious effects because of greatly increased use of land near volcanoes during the present century. (See "Appraising Volcanic Hazards of the Cascade Range of the Northwestern United States," Earthquake Inf. Bull., Sept.-Oct. 1974.) The recognition an impending eruption is highly important in order to minimize the potential hazard to people and property. Thus, a substantial increase in hydrothermal activity at Mount Baker in March 1975 ( see "Mount Baker Heating Up," July-Aug. 1975 issue) was regarded as a possible first signal that an eruption might occur, and an intensive monitoring program was undertaken.

Washington↗
USGS1980

Earthquake education in California

In a survey of community response to the earthquake threat in southern California, Ralph Turner and his colleagues in the Department of Sociology at the University of California, Los Angeles, found that the public very definitely wants to be educated about the kinds of problems and hazards they can expect during and after a damaging earthquake; and they also want to know how they can prepare themselves to minimize their vulnerability. Decisionmakers, too, are recognizing this new wave of public concern.

Earthquake Information Bulletin (USGS)↗
USGS1982

Seismology in Mexico

Mexico is situated at the intersection of four major crustal Plates: the Americas Plate, the Pacific Plate, the Caribbean Plate, and the Cocos Plate. The interaction of these four plates is very complex. The pattern of earthquake risk is, therefore, among the most complicated in the world. The average release of seismic energy each is 55x10 21 ergs-more than twice the figure for California.

Earthquake Information Bulletin (USGS)↗
USGS1985

Natural hazards activities of the National Geophysical Data Center

The National Geophysical Data Center (NGDC), a part of the National Oceanic and Atmospheric Administration, has been given the task of collecting, managing, and disseminating the great mass of inofmation produced by scientific observations of the geophysical environment. This article describes NGDC data bases that speifically relate to natural hazards.

Earthquake Information Bulletin (USGS)↗
USGS1978

Amplitude of foreshocks as a possible seismic precursor to earthquakes

In recent years, we have made significant progress in being able to recognize the long-range pattern of events that precede large earthquakes. For example, in a recent issue of the Earthquake Information Bulletin, we saw how the pioneering work of S.A. Fedotov of the U.S.S.R in the Kamchatka-Kurile Islands region has been applied worldwide to forecast where large, shallow earthquakes might occur in the next decades. Indeed, such a "seismic gap" off the coast of Alaska was filled by the 1972 Sitka earthquake. Promising results are slowly accumulating from other techniques that suggest that intermediate-term precursors might also be seen: among these are tilt and geomagnetic anomalies and anomalous land uplift. But the crucial point remains that short-term precursors (days to hours) will be needed in many cases if there is to be a significant saving of lives.

Earthquake Information Bulletin (USGS)↗
USGS1979

The Parkfield prediction experiment

The San Andreas fault is part of the boundary between the Pacific and North American crustal plates. In California, movements of about 3 centimeters per year are currently taking place along the fault, although plat tectonic models suggest a faster rate of 5 cm/yr may be the average over a longer period of time and a broader area. There are two distinct ways in which movement on the San Andreas occurs. Along most of the fault, slip occurs during infrequent great earthquakes. Examples of these in historic time are the 1857 Fort Tejon and the 1906 San Francisco events. Along these portions of the fault, it appears that, during most of the intervening period between great earthquakes, no slip and few microearthquakes occurred. Strain appears to accumulate at shallow depths in a narrow (50 kilometer) zone adjacent to the fault. Along a 200-km stretch in central California, however, continuous slip occurs with no observable accumulation of strain. Although there is a high level of microseismicity here, earthquakes larger than magnitude (M) 6 are unknown, and most of the slip occurs aseismically. (Several articles in the Earthquake Information Bulletin in 1978 have covered this topic.) At the northern end of this creeping zone, the microseismicity and the slip gradually taper to zero over a distance of about 100 km. This segment is the site of frequent earthquakes (every 5-10 years) having magnitudes of 5.5 and less. At the southern end, near the town of Parkfield, the transition occurs in about 40km. This zone is the site of recurring earthquakes of about magnitude 6.

California↗
USGS1980

An economical educational seismic system

There is a considerable interest in seismology from the nonprofessional or amateur standpoint. The operation of a seismic system can be satisfying and educational, especially when you have built and operated the system yourself. A long-period indoor-type sensor and recording system that works extremely well has been developed in the James Madison University Physics Deparment. The system can be built quite economically, and any educational institution that cannot commit themselves to a professional installation need not be without first-hand seismic information. The system design approach has been selected by college students working a project or senior thesis, several elementary and secondary science teachers, as well as the more ambitious tinkerer or hobbyist at home

Earthquake Information Bulletin (USGS)↗
USGS1979

Microearthquake networks and earthquake prediction

A microearthquake network is a group of highly sensitive seismographic stations designed primarily to record local earthquakes of magnitudes less than 3. Depending on the application, a microearthquake network will consist of several stations or as many as a few hundred . They are usually classified as either permanent or temporary. In a permanent network, the seismic signal from each is telemetered to a central recording site to cut down on the operating costs and to allow more efficient and up-to-date processing of the data. However, telemetering can restrict the location sites because of the line-of-site requirement for radio transmission or the need for telephone lines. Temporary networks are designed to be extremely portable and completely self-contained so that they can be very quickly deployed. They are most valuable for recording aftershocks of a major earthquake or for studies in remote areas.

Earthquake Information Bulletin (USGS)↗
USGS1971

Results from the apollo-12 passive seismic experiment

The objective of the passive seismic experiment is to measure vibrations of the lunar surface produced by all natural and artificial sources of seismic energy and to use these data to deduce the internal structure and composition of the moon, the nature of forces which may cause deformation of the moon and moonquakes, and the numbers and masses of meteoroids striking the lunar surface. The ALSEP* seismometers can magnify lunar surface vibrations 10 million times. No instrument can operate on earth with this sensitivity, because weather and man produce too much seismic noise. To obtain answers to the above questions, seismic data must be combined with data from laboratory measurements of the physical and chemical properties of surface rocks, and many other geophyiscal and geochemical measurements. Thus far, we have had the opportunity to record data from two lunar seismic stations which were installed by the astronauts during Apollo misions and 12. The combined recording time from the stations is presently over 12 months, but there was no overlap to permit recording of the same event at two stations.

Earthquake Information Bulletin (USGS)↗