Image by California Geological Survey
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The California Geological Survey has published a few landslide inventory maps for selected 7.5 minute quadrangles in the state. Supervising Geologist Chuck Real, a program head at CGS, says that the maps are produced under the idea that “The most likely places for landslides to occur are the places where they’ve happened in the past." Thus, an inventory of historic landslide activity is logical. These maps should also help avoid property development on ancient landslides. Landslide areas on the maps have been placed into four different categories:
Active or Historic Landslides: The landslide appears to be currently moving (at the time the aerial photograph was taken or field observation occurred) or to have moved within historic time.
Dormant - Young Landslides: The observed landforms related to the landslide are fresh or uneroded, but there is no evidence of historic movement.
Dormant - Mature Landslides: The observed landforms related to the landslide have been smoothed and subdued by erosion and vegetation.
Dormant - Old Landslides: The observed landforms related to the landslide have been greatly eroded, including significant gullies or canyons cut into the landslide mass and/or main scarp by small streams.
Landslide Map by California Geological SurveyThe map above shows locations of dormant landslides in color with movement directions shown by arrows. From this sample map it is clear to see that some development has occurred directly upon dormant landslides. This type of mapping will inform of current problems and help development and home purchase decisions to be made with improved information.
More information about these maps and access to the .pdf documents can be obtained at the CGS
Landslide Inventory Map webpage.
Labels: Landslides, Maps
A portion of the USGS Landslide Overview map - red areas have more than 15% of the land area involved in active or geologically recent landslide processes.
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Native Americans recognized the landslide problems in the Pittsburgh area. Their name for the Monongahela River means "the banks that slip into the water". The unstable soils that gave the Monongahela its name are widespread in the Pittsburgh area. Combine these soils with a high population living on steep hillsides and you have a city that is very vulnerable to an ongoing series of landslide problems.
The latest problem has resulted in landslides that have blocked all four lanes of Route 65, known as Ohio River Boulevard, closed three railroad lines and resulted in the suspension of the Kilbuck Properties building permit for River Pointe Plaza, a shopping center complex. The slide occurred on September 22nd, rail traffic resumed today, but Route 65 remains buried under thousands of tons of mud, rock and debris.
Read more about the
Pittsburgh Landslide at ThePittsburghChannel.com.
Labels: Landslides
Preliminary news reports about the catastrophic landslides in the
Philippines were very conservative in regards to the amount of damage done and lives lost. Up to 1800 are now feared dead.
Read more about the landsides at the
Washington Post website.
Labels: Landslides
Large landslides in the
Philippines, triggered by heavy rain, have caused extensive damage with large residental areas being completely inundated with mud. Injuries and many deaths have already been confirmed. The most severe damages have been in the communities of San Francisco, Liloan and Maasin in southern Leyte, and the Agusan and Surigao areas of Mindanao.
Read early reports about these landslides at
BBC Website and
Reuters UK.
Labels: Landslides
The United States Geological Survey has published a number of preliminary soil-slip susceptibility maps for southwestern
California. These maps show relative susceptibility of hill slopes to the initiation of rain-triggered soil slip-debris flows. The maps were created by considering slope, bedrock characteristics, and the presence of historic landslide problems in each study area. The timing of landslides is determined mainly by precipitation. Read about these
landslide hazard maps at the USGS website.
Labels: Landslides
A large landslide has closed the southbound lane of US Route 15 between Tioga and Mansfield in Tioga County,
Pennsylvania. The slide has been moving slowly for the past several months. The first photo below is looking north and shows the head of the slide as a depression in the highway. The second photo, looking south shows fractured pavement in the scarp zone. Photos submitted by Kevin Thomas of KC101.5 FM Radio.
Labels: Landslides
A portion of the Beartooth Highway, one of the gateways into Yellowstone Park, has been closed by a large mudslide. More information can be found at the
Casper Star Tribune website.
Labels: Landslides
