Open-File Report 96-517
Some 15,000 landslides were mapped following the Northridge earthquake [Harp & Jibson, 1995]. Five of the anomalous BMs are found on or within several hundred meters of the slides, suggesting that the BMs were moved downslope with the underlying material (BMs 1, 2 , 22, 23, and 27 on the map and in Table 3). BM 1 (EW9445) is in a building foundation that may have suffered from shaking or landslide effects. Roads, pipelines, and structures sited near the slides may also be affected by continuing downslope movement of the landslides, particularly during periods of heavy rainfall. BM 27 (EW4865) is in the headwall a concrete bridge, and might indicate incipient damage to the bridge.
Eighteen sites where near surface materials were subject to shaking-induced liquefaction were identified following the earthquake, as well as 4 additional sites of possible liquefaction [Holzer et al., 1996; U.S. Geological Survey Staff, 1996]. Two BMs are located close to the liquefaction regions (BMs 29 in Simi Valley, and BM 35 in the northern San Fernando Valley, Table 3 and map). BM 29 (EW6942) is located in railroad bridge 38.40, above a double flood-control culvert in Simi Valley. Thus the bridge and culvert may have settled or been damaged as a result of shaking-induced liquefaction. In contrast, some twelve BMs located within 300 m of the mapped liquefaction sites were undisturbed, demonstrating that liquefaction is generally a localized phenomenon.
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://pubsdata.usgs.gov/pubs/of/1996/0517/fema/html/FEMA-3.3.html
Page Contact Information: GS Pubs Web Contact
Page Last Modified: Wednesday, 07-Dec-2016 16:08:16 EST
