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At least 523 records · Page 29Linked to original sources
USGS2004

Usoi Landslide Dam and Lake Sarez, Pamir Mountains, Tajikistan

In 1911, a 2-km 3 (0.5-mi 3 ) earthquake-triggered rock slide blocked the Murgab River, southeastern Tajikistan, forming a still-existing, 600-m-high (1,970-ft-high) natural dam—the highest dam, natural or man-made, in the world. Lake Sarez, impounded by this blockage, is 60 km (37 mi) long, with a maximum depth of 550 m (1,800 ft) and a volume of approximately 17 km 3 (∼4 mi 3 ). This lake, which has never overtopped the dam, exits the downstream face as a series of large springs that regroup as the Murgab River. Freeboard between lake surface and the lowest point on the dam crest currently is approximately 50 m (∼165 ft), and the lake is rising at an average rate of 18.5 cm/yr (7.3 in./yr). If the blockage were to fail, a worst-case scenario could endanger tens or possibly hundreds of thousands of people in the Murgab, Bartang, Panj, and Amu Darya valleys downstream. Dam failure potentially could result from: 1) seismic shaking, 2) catastrophic overtopping caused by a landslide entering the lake from the valley wall at high velocity, 3) surface erosion caused by natural overtopping by the rising lake, 4) internal erosion (piping), 5) instability caused by lake pressure against the dam, or 6) slope instability of the dam faces. Occurrence of an overtopping wave resulting from a potential landslide high on the right bank of Lake Sarez seems to be the most realistic of these slight possibilities for failure. Because of the high cost of installing physical remediation to the dam in this rugged mountain area (no roads lead to the site), the main protective measures now being undertaken are hydrological monitoring at the dam and installation of a flood early warning system downstream.

Lake Sarez↗
USGS1994

Modeling and analysis of the 1949 Narrows landslide, Tacoma, Washington

A large landslide failed catastrophically along steep, 90-m (300-ft) high bluffs overlooking the waters of Puget Sound at Tacoma, Washington, in April of 1949, three days after the region was struck by a magnitude 7.1 earthquake. The area of failure was investigated to estimate the static and seismic stability of the pre-earthquake slope and to identify factors that contributed to the failure. Results of static analyses suggest that the slope was marginally stable and that high ground-water conditions would have significantly reduced slope stability. The Newmark analysis of dynamic (seismic) slope stability was used to calculate predicted inertial displacements for the landslide for a range of possible material property and ground-water conditions. Comparison of predicted displacements with a reported displacement suggests that the ground motion could have initiated the large-scale failure. Results of the study provide a basis for discussion and comparison of similar bluffs in the Puget Sound region that may be susceptible to catastrophic, earthquake-induced slope failure.

Washington↗
USGS2000

Landslide Hazards

Landslide hazards occur in many places around What Can You Do If You Live Near Steep Hills? the world and include fast-moving debris flows, slow-moving landslides, and a variety of flows and slides initiating from volcanoes. Each year, these hazards cost billions of dollars and cause numerous fatalities and injuries. Awareness and education about these hazards is a first step toward reducing damaging effects. The U.S. Geological Survey conducts research and distributes information about geologic hazards. This Fact Sheet is published in English and Spanish and can be reproduced in any form for further distribution.

Fact Sheet↗
USGS2007

Landslide hazards in the Seattle, Washington, area

The Seattle, Washington, area is known for its livability and its magnificent natural setting. The city and nearby communities are surrounded by an abundance of rivers and lakes and by the bays of Puget Sound. Two majestic mountain ranges, the Olympics and the Cascades, rim the region. These dramatic natural features are products of dynamic forces-landslides, earthquakes, tsunamis, glaciers, volcanoes, and floods. The same processes that formed this beautiful landscape pose hazards to the ever-growing population of the region. Landslides long have been a major cause of damage and destruction to people and property in the Seattle area.

Washington↗
USGS2022

New model of the Barry Arm landslide in Alaska reveals potential tsunami wave heights of 2 meters, values much lower than previously estimated

The retreat of Barry Glacier has contributed to the destabilization of slopes in Barry Arm, creating the possibility that a landslide could rapidly enter the fjord and trigger a tsunami. The U.S. Geological Survey (USGS) recently released a report documenting potential tsunami wave heights in the event of a large, fast-moving landslide at the Barry Arm fiord near Prince William Sound, Alaska (Barnhart and others, 2021). This new work shows that the largest plausible wave height is smaller than initial estimates published in Dai and others (2020), but waves still represent a substantial hazard to the people who live, work, and recreate in Prince William Sound. Thus, it is important that residents and visitors remain informed about this hazard and prepare accordingly.

Alaska↗
USGS1999

Map showing locations of damaging landslides in Napa County, California, resulting from 1997-98 El Nino rainstorms

Heavy rainfall associated with a strong El Nino caused over $150 million in landslide damage in the 10-county San Francisco Bay region during the winter and spring of 1998. A team of USGS scientists collected information on landslide locations and damage costs. Napa County was relatively unaffected in comparison to other counties in the region with approximately $1.1 million in damages assessed.

Miscellaneous Field Studies Map↗
USGS1999

Map showing locations of damaging landslides in Alameda County, California, resulting from 1997-98 El Nino rainstorms

Heavy rainfall associated with a strong El Nino caused over $150 million in landslide damage in the 10-county San Francisco Bay region during the winter and spring of 1998. A team of USGS scientists collected information on landslide locations and damage costs. In Alameda County more than $20 million in damages were assessed. Debris flows occurred in rural portions of the county, but were only responsible for $400 thousand in damages.

Miscellaneous Field Studies Map↗
USGS2001

Seismic Landslide Hazard for the Cities of Oakland and Piedmont, California

This map describes the possible hazard from earthquake-induced landslides for the cities of Oakland and Piedmont, CA. The hazard depicted by this map was modeled for a scenario corresponding to an M=7.1 earthquake on the Hayward, CA fault. This scenario magnitude is associated with complete rupture of the northern and southern segments of the Hayward fault, an event that has an estimated return period of about 500 years. The modeled hazard also corresponds to completely saturated ground-water conditions resulting from an extreme storm event or series of storm events. This combination of earthquake and ground-water scenarios represents a particularly severe state of hazard for earthquake-induced landslides. For dry ground-water conditions, overall hazard will be less, while relative patterns of hazard are likely to change.

Miscellaneous Field Studies Map↗
USGS1971

Preliminary photointerpretation map of landslide and other surficial deposits of the Mount Diablo area, Contra Costa and Alameda Counties, California

The map shows the distribution of landslide and other surficial deposits by presenting the writer's best judgement regarding the origins of the various parts of the present landscape. It is based completely on the interpretation of aerial photographs through a stereoscope, which permits a three-dimentional relief model of the ground surface to be seen, enables the geologist to study and interpret the origins of landforms with considerable ease. In fact, photointerpretation provides many advantages over both ground observations and laboratory studies of surficial materials in the mapping of surficial deposits, particularily for reconnaissance-type studies. Of course, better information can be provided when all aspects of the studyy are integrated. These preliminary photointerpretation maps are the inital stage of a continuing, more detailed study of surficial deposits in the Bay region, but they will hopefully provide map users with immediately useful information about the regional distribution of landslide and other surficial deposits.

California↗
USGS1972

Landslide susceptibility in San Mateo County, California

Information on areas susceptible to failure by landsliding is available in many general geologic maps and reports. However, it is commonly presented in complex, technical language, together with data not connected with slope stability. This derivative map is intended to convey such information in nontechnical form so that it will be intelligible to the non-geologist. It portrays only those geologic factors that bear directly on the susceptibility of specific areas to landsliding.

California↗
USGS2002

Landslides triggered by Hurricane Mitch in Tegucigalpa, Honduras

The arrival of Hurricane Mitch in Honduras in the latter part of the 1998 hurricane season produced effects that were unprecedented in their widespread nature throughout Central America. After winds from the storm had blown down more than 70 percent of the conifer forest on the Bay Island of Guanaja, the hurricane turned inland and stalled over the mainland of Honduras for 3 days. The resulting deluge of rainfall produced devastating flooding and landslides that resulted in more than 9,000 fatalities and 3 million people displaced. Although the eye of Hurricane Mitch passed through the northern part of Honduras, the greatest rainfall totals and intensities occurred in the southern part of the country near Choluteca. For the three days October 29-31, 1998, total rainfall at Choluteca exceeded 900 mm. Not surprisingly, it was in this area that the highest landslide concentrations occurred.

Open-File Report↗