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International decade for natural disaster reduction

Throughout history, humanity has found itself in conflict with naturally occurring events of geologic, hydrologic, and atmospheric origin. this conflict has been demonstrated repeatedly when people build urban centers at the water's edge, in or near active fault systems capable of generating earthquakes, on steep slopes, near active volcanoes, or at the urban-wilderness interface prone to wildfires. Naturally occurring, recurrent events such as floods, windstorms, tsunamis, earthquakes, landslides, volcanic eruptions, and wildfires have tested human-engineered works many times and have often found them unable to withstand the forces generated by the event. In the past 20 years, for example, events like these throughout the world have claimed more than 2.8 million lives and adversely affected 820 million people; single disasters have caused economic losses of billions of dollars. Industrialized countries like the United States and Japan have been able to absorb the socioeconomic losses of past natural disasters, but the economics of many developing countries have been devastated by losses equal to a large percentage of their gross national product. Furthermore, the magnitude of the losses is increasing at a rapid rate as the building wealth of nations is expanded to meet the needs of rapidly increasing population, often without adequate consideration of the potential threat posed by the recurrent natural hazards and without implementing effective loss-reduction measures because of lack of knowledge or lack of technical capability.

Earthquakes & Volcanoes (USGS)

Assessing the earthquake hazards in urban areas

Major urban areas in widely scattered geographic locations across the United States are a t varying degrees of risk from earthquakes. the locations of these urban areas include Charleston, South Carolina; Memphis Tennessee; St.Louis, Missouri; Salt Lake City, Utah; Seattle-Tacoma, Washington; Portland, Oregon; and Anchorage, Alaska; even Boston, Massachusetts, and Buffalo New York, have a history of large earthquakes. Cooperative research during the past decade has focused on assessing the nature and degree of the risk or seismic hazard i nthe broad geographic regions around each urban area. The strategy since the 1970's has been to bring together local, State, and Federal resources to solve the problem of assessing seismic risk. Successfl sooperative programs have been launched in the San Francisco Bay and Los Angeles regions in California and the Wasatch Front region in Utah.

Earthquakes & Volcanoes (USGS)

The Golden bypass landslide, Golden, Colorado

Slope instability along a new highway bypass in Golden, Colorado, became a major concern in 1993. Rains and snowmelt accelerated movement of a landslide that had begun to develop before the bypass was opened to traffic in July of 1991. The downslope movement of earth materials increased significantly in 1993. During the first few months of the year, the landslide pushed onto the west shoulder of the road and crumpled the pavement beneath the south-bound lane. As we prepare this article (September, 1993), the slide continues to encroach onto the highway, posing a persistent problem despite repeated efforts to slow or stop its movement. As this article will show, permanent solutions to landslide problems of this kind are difficult to obtain.

Colorado

Smithsonian traveling exhibition highlights two active volcanoes

Over time, active volcanoes have captured human fascination, not only because of their strange and dramatic beauty, but also because of their power to destroy. Two active U.S volcanoes-one on the Big Island of Hawaii, the other part of the Cascade Range in the Pacific Northwest-will be the focus of "Inside Active Volcanoes: Kilauea and Mount St. Helens." This major exhibit opened July 6 in the Evans Gallery of the Smithsonian's National Museum of Natural history in Washington, D.C, and continued through September 24.

Earthquakes & Volcanoes (USGS)

Land subsidence

In November 1966, sixty percent of Venice, Italy, is inundated by a storm surge that causes waters in the Venetian lagoon to rise more than 6 feet. On December 28, 1971, a janitor at the Washington Elementary School in Johnston City, Illinois, discovers sever cracking of the school. In January 1972, the school is abandoned and subsequently razed. In the 1970's, five homes in New Orleans, Louisiana, are destroyed by gas explosins. In May 198, a 350 feet diameter sink-hole forms in a business area in Winter Park, Florida, and swallows a home and parts of several businesses. In August 1983, Hurricane Alicia slams into the texas Gulf Coast near Houston, Texas, and devastates the 500 home Brownwood subdivision on the north end of Galveston Bay. Homes are torn from their foundations and reduced to rubble.

Earthquakes & Volcanoes (USGS)

An earthquake strength scale for the media and the public

Let's face it: seismologists do a pretty poor job of communicating the facts about our science to the public. Earthquake magnitude is the classic example. How many of us have struggled to explain the Richter scale? We explain that it is logarithmic, with each unit indicating a factor of 10 increase, but this really represents a factor of 32 increase in intrinsic earthquake size, and in any case we don't use the Richter scale anymore. By then the unfortunate listener is reeling and can be dispatched quietly by mentioning negative magnitudes or saturation. We even wonder why the audience or the reporter has this glazed look when we we finish. A local engineer, E.P Hailey, pointed this problem out to me shortly after the Loma Prieta earthquake. He felt that three problems limited the usefulness of magnitude in describing an earthquake to the public; (1) most people don't understand that it is not a linear scale; (2) of those who do realized the scale is not linear, very few understand the difference of a factor of ten in ground motion and 32 in energy release between points on the scale; and (3) even those who understand the first two points have trouble putting a given magnitude value into terms they can relate to. In summary, Mr. Hailey wondered why seismologists can't come up with an earthquake scale that doesn't confuse everyone and that conveys a sense of true relative size. Here, then, is m attempt to construct such a scale.

Earthquakes & Volcanoes (USGS)

Forecasting California’s earthquakes

The first official earthquake forecast for California emphasizes the broad extent of the hazard and the uncertainties involved in predicting the next quakes. For the first time, researchers have reached to a consensus on the threat of large earthquakes to California, things look no worse for Los Angles than before. It still has about a 60 percent chance of being shaken by a large earthquake sometime during the next 30 years. But other heavily populated areas of California, such as San Bernardino and the East Bay area of San Francisco, are now getting their fair share of attention. The new consensus also points up the considerable uncertainties invloved in earthquake forecasting.

California

What is worse than the “big one”?

The Whittier Narrows California earthquake sequence (local magnitude, Ml=5.9 or 1 October, 1987), which caused over $358 million damage, indicates that assessments of earthquake hazards in Los Angeles metropolitan area may be underestimated. the sequence ruptured a previously unidentified thrust fault that may be part of a large system of thrust faults that extends across the entire east-west length of the northern margin of the Los Angeles basin. Peak horizontal accelerations from the main shock, which were measured at ground level and in structures, were as high as 0.6g (where g is acceleration of gravity at sea level) within 50 kilometers of the epicenter The first thought in the minds of many residents of the city of Whittier when the first shock hit them was "Is this the big one?" the San Andreas' once-in-150-years great shaker? It might as well have been for Whittier, which is 20 kilometers east of downtown Los Angeles. The ground shook harder there this month than it will when the big one does strike the distant San Andreas, which lies 50 kilometers on the other side of the mountains. And this was only a moderate, magnitude 6.1 shock. Earthquake of magnitude 7 and large 30 times more powerful, could rupture faults beneath the feet of Angelenos at any time. The loss of life and destruction could exceed that caused by the big one.

California

New fault picture points toward San Francisco Bay area earthquakes

Recent earthquakes and a new way of looking at faults suggest that damaging earthquakes are closing in on the San Francisco area. Earthquakes Awareness Week 1989 in northern California started off with a bang on Monday, 3 April, when a magnitude 4.8 earthquake struck 15 kilometers northeast of San Jose. The relatively small shock-its primary damage was the shattering of an air-control tower window-got the immediate attention of three U.S Geological Survey seismologists in Menlo Park near San Francisco. David Oppenheimer, William Bakun, and Allan Lindh had forecast a nearby earthquake in a just completed report, and this, they thought, might be it.

California

Notes about the Armenia earthquake, 7 December 1988

The Earth's crust is a jigsaw of rigid plates like huge paving stones. According to the theory of plate tectonics, these lithosphere plates are constantly in motion, slowly realigning themselves with the passage of time. Ninety to niety-five percent of all earthquakes occur where the plates collide with each other. In Armenia, the Arabian plate abuts against the Eurasian (Europe-Asia) plate. As a result, the region has been plagued by sever earthquakes for thousands of years: an earthquake in 893 A.D. took an estimated 20,000 lives; another in 1667 took 80,000 lives. Whenever the plates moving beneath Armenia interlock, pressure builds. The stress increases, the pressure continues to climb and finally there is a fracture-a sudden release of energy we know as an earthquake.

Earthquakes & Volcanoes (USGS)

Taking the pulse of the San Andreas Fault

The ninth of January, 1989, was the 32nd anniversary of the great southern California earthquake of 1857. the latest research shows that, on average, at least part of the section of the San Andreas fault that broke then should break again this year. But the same research suggests that the fault's average behavior could be misleading. A newly refined dating of the past 10 San Andreas ruptures adjacent to Los Angeles reveals a previously unrecognized clustering of large earthquakes in bunches of two or three. If this pattern were to hold, Los Angeles would wait at least another 80 years for another jolt from there. But the San Andreas is not that easy to get around.

California

The Moon; twenty years later

The 20th anniversary of the first landing on the Moon occurred on July 21, 1989. The vast majority of the Moon rocks collected by the Apollo mission astronauts await further study in the continuing effort to unravel the origin and evolution of Earth's nearest neighbor. Not that the 382-kilogram treasure trove of lunar samples has been gathering dust in the Planetary Materials Laboratory at the Johnson Space Center in Houston. It is just that lunar scientists are being very sparing in their use of the rocks.

Earthquakes & Volcanoes (USGS)

Triumph of the Voyager mission

It had been a long, productive trip. Launched in 1977, the two Voyager spacecraft had visited three giant planets, a dozen major Moons, three ring systems with thousands of rings composed of a myriad of tiny Moonlets. The spacecraft had returned 5 trillion bits of data and over 100,000 photographs. The last encounter in our Solar System by Voyager 2 with Neptune was to be a spectacular finale to the 12-year drama.

Earthquakes & Volcanoes (USGS)

Volcanoes and atmospheres; catastrophic influences on the planets

For a rare and brief instant in geologic time, we can imagine that the sulfurous, chromatic surface of Io (one of the satellites of Jupiter) lies quiet. Perhaps stars glisten brilliantly through the tenuous nigh sky. Here and there, thick icy fogs enshroud fumaroles where sulfur dioxide leaks from the underworld. Suddenly, a fissure splits the surface and billowing clouds of sulfurous gases and ice hurl orange and black ash into the atmosphere. Minute by minute, the intensity of the eruption builds; stars begin disappearing from the night sky. The rising plume inhales the nearby atmosphere, mixing it with the exhalations from the volcano. Particles of sulfur, sulfur dioxide snow and ash rise to 300 kilometers, later raining down across the planet a thousand kilometers away.

Earthquakes & Volcanoes (USGS)

Intermediate-term earthquake prediction

The problems in predicting earthquakes have been attacked by phenomenological methods from pre-historic times to the present. The associations of presumed precursors with large earthquakes often have been remarked upon. the difficulty in identifying whether such correlations are due to some chance coincidence or are real precursors is that usually one notes the associations only in the relatively short time intervals before the large events. Only rarely, if ever, is notice taken of whether the presumed precursor is to be found in the rather long intervals that follow large earthquakes, or in fact is absent in these post-earthquake intervals. If there are enough examples, the presumed correlation fails as a precursor in the former case, while in the latter case the precursor would be verified. Unfortunately, the observer is usually not concerned with the 'uniteresting' intervals that have no large earthquakes.

Earthquakes & Volcanoes (USGS)

The October 1992 Parkfield, California, earthquake prediction

A magnitude 4.7 earthquake occurred near Parkfield, California, on October 20, 992, at 05:28 UTC (October 19 at 10:28 p.m. local or Pacific Daylight Time).This moderate shock, interpreted as the potential foreshock of a damaging earthquake on the San Andreas fault, triggered long-standing federal, state and local government plans to issue a public warning of an imminent magnitude 6 earthquake near Parkfield. Although the predicted earthquake did not take place, sophisticated suites of instruments deployed as part of the Parkfield Earthquake Prediction Experiment recorded valuable data associated with an unusual series of events. this article describes the geological aspects of these events, which occurred near Parkfield in October 1992. The accompnaying article, an edited version of a press conference b Richard Andrews, the Director of the California Office of Emergency Service (OES), describes governmental response to the prediction.

California

Seismicity and volcanism; a global perspective

Earthquakes and volcanic eruptions are episodic, related phenomena, resulting from an unstable, evolving Earth. Earthquakes span at least 2 orders of magnitude of energy release (2 of Richter magnitude), and volcanic eruptions at least 3 orders of magnitude in both volume and energy. The largest known earthquakes, of magnitude about 9.5 (as in Chile in 1960), occur somewhere on Earth on average once in less than 100 years. By contrast, the largest volcanic eruptions may exceed 10,00 km 3 in volume, with intervals between them averaging more than 1 million years. The largest documented eruptions have ejected some 3,000 km 3 of material and occur globally on average once in 50,000 to 100,000 years. No known seismic phenomenon has a comparable return interval.

Earthquakes & Volcanoes (USGS)