Inventory of landslides in southern Illinois near the New Madrid Seismic Zone and the possible failure mechanism at three sites

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5587140

Su, Wen June ^[1]

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1. Illinois State Geological Survey, Champaign, IL (United States). Engineering Geology Section

A total of 221 landslides was inventoried along a 200-kilometer reach of the Ohio and the Mississippi Rivers from Olmsted to Chester, IL using Side-Looking Airborne Radar imagery, vertical, stereoscopic, black and white aerial photography at various scales, and low altitude, oblique color and color infrared photography. Features observed on aerial photographs were used to classify landslides into three types (rock/debris fall, block slide, and rotational/translational slide) at three levels of confidence: certain, probable, or possible. Some landslides combined two or more types at a single site. Only a few of the landslides showed evidence of repeated activity; most are ancient landforms. Most of the landslides were developed in the loess, alluvium, colluvium, and weak clay layers of the Chesterian Series or in the Porter's Creek Clay and McNairy Formation. Failure of three representative landslides was modeled under static (aseismic) and dynamic (seismic) situations using three different sliding mechanisms. Both the pseudo-static method and a simplified method of the Newmark displacement analysis were used to determine the stability of the slope under earthquake conditions. The three representative landslides selected for detailed slope stability analysis were the Ford Hill, Jones Ridge, and Olmsted landslides. The Ford Hill and Jones Ridge landslides have similar slope geometries. Their modes of failure were recognized as a translational block slide on a weak clay layer. The Olmsted landslide is a complex of several rotational slides of different ages and a mega block slide on weak clay layers. The stability analyses of these three landslides suggest that they would not have occurred under aseismic conditions. However, under earthquake loadings similar to those generated by the 1811-12 earthquakes, most of the slopes could have experienced large displacements leading to landslide initiation.

• OSTI ID: 5587140
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540250 -- Environment
Terrestrial-- Site Resource & Use Studies-- (1990-)
58 GEOSCIENCES
580000* -- Geosciences
CLASSIFICATION
DEVELOPED COUNTRIES
EARTHQUAKES
FAILURE MODE ANALYSIS
ILLINOIS
INVENTORIES
LANDSLIDES
MATHEMATICAL MODELS
MECHANICS
MISSISSIPPI RIVER
NORTH AMERICA
OHIO RIVER
RIVERS
ROCK MECHANICS
SEISMIC EVENTS
SLOPE STABILITY
STABILITY
STREAMS
SURFACE WATERS
SYSTEM FAILURE ANALYSIS
SYSTEMS ANALYSIS
USA