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John A. Michael

Publications and source records attributed to John A. Michael.

33 records · Page 2Linked to original sources
USGS2007

Emergency Assessment of Debris-Flow Hazards from Basins Burned by the 2007 Witch Fire, San Diego County, Southern California

INTRODUCTION The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Witch Fire in San Diego County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 2.25 inches (57.15 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

Open-File Report↗
USGS2007

Emergency assessment of debris-flow hazards from basins burned by the 2007 Harris Fire, San Diego County, southern California

Introduction The objective of this report is to present a preliminary emergency assessment of the potential for debris-flow generation from basins burned by the Harris Fire in San Diego County, southern California in 2007. Debris flows are among the most hazardous geologic phenomena; debris flows that followed wildfires in southern California in 2003 killed 16 people and caused tens of millions of dollars of property damage. A short period of even moderate rainfall on a burned watershed can lead to debris flows. Rainfall that is normally absorbed into hillslope soils can run off almost instantly after vegetation has been removed by wildfire. This causes much greater and more rapid runoff than is normal from creeks and drainage areas. Highly erodible soils in a burn scar allow flood waters to entrain large amounts of ash, mud, boulders, and unburned vegetation. Within the burned area and downstream, the force of rushing water, soil, and rock can destroy culverts, bridges, roadways, and buildings, potentially causing injury or death. This emergency debris-flow hazard assessment is presented as relative ranking of the predicted median volume of debris flows that can issue from basin outlets in response to 1.75 inches (44.45 mm) of rainfall over a 3-hour period. Such a storm has a 10-year return period. The calculation of debris flow volume is based on a multiple-regression statistical model that describes the median volume of material that can be expected from a recently burned basin as a function of the area burned at high and moderate severity, the basin area with slopes greater than or equal to 30 percent, and triggering storm rainfall. Cannon and others (2007) describe the methods used to generate the hazard maps. Identification of potential debris-flow hazards from burned drainage basins is necessary to issue warnings for specific basins, to make effective mitigation decisions, and to help plan evacuation timing and routes.

California↗
USGS2006

Shallow-landslide hazard map of Seattle, Washington

Landslides, particularly debris flows, have long been a significant cause of damage and destruction to people and property in the Puget Sound region. Following the years of 1996 and 1997, the Federal Emergency Management Agency (FEMA) designated Seattle as a 'Project Impact' city with the goal of encouraging the city to become more disaster resistant to the effects of landslides and other natural hazards. A major recommendation of the Project Impact council was that the city and the U.S. Geological Survey (USGS) collaborate to produce a landslide hazard map of the city. An exceptional data set archived by the city, containing more than 100 years of landslide data from severe storm events, allowed comparison of actual landslide locations with those predicted by slope-stability modeling. We used an infinite-slope analysis, which models slope segments as rigid friction blocks, to estimate the susceptibility of slopes to shallow landslides which often mobilize into debris flows, water-laden slurries that can form from shallow failures of soil and weathered bedrock, and can travel at high velocities down steep slopes. Data used for analysis consisted of a digital slope map derived from recent Light Detection and Ranging (LIDAR) imagery of Seattle, recent digital geologic mapping, and shear-strength test data for the geologic units in the surrounding area. The combination of these data layers within a Geographic Information System (GIS) platform allowed the preparation of a shallow landslide hazard map for the entire city of Seattle.

Open-File Report↗
USGS2004

Hazard analysis of landslides triggered by Typhoon Chata’an on July 2, 2002, in Chuuk State, Federated States of Micronesia

More than 250 landslides were triggered across the eastern volcanic islands of Chuuk State in the Federated States of Micronesia by torrential rainfall from tropical storm Chata’an on July 2, 2002. Landslides triggered during nearly 20 inches of rainfall in less than 24 hours caused 43 fatalities and the destruction or damage of 231 structures, including homes, schools, community centers, and medical dispensaries. Landslides also buried roads, crops, and water supplies. The landslides ranged in volume from a few cubic meters to more than 1 million cubic meters. Most of the failures began as slumps and transformed into debris flows, some of which traveled several hundred meters across coastal flatlands into populated areas. A landslide-inventory map produced after the storm shows that the island of Tonoas had the largest area affected by landslides, although the islands of Weno, Fefan, Etten, Uman, Siis, Udot, Eot, and Fanapanges also had significant landslides. Based on observations since the storm, we estimate the continuing hazard from landslides triggered by Chata’an to be relatively low. However, tropical storms and typhoons similar to Chata’an frequently develop in Micronesia and are likely to affect the islands of Chuuk in the future. To assess the landslide hazard from future tropical storms, we produced a hazard map that identifies landslide-source areas of high, moderate, and low hazard. This map can be used to identify relatively safe areas for relocating structures or establishing areas where people could gather for shelter in relative safety during future typhoons or tropical storms similar to Chata’an.

Chuuk State↗
USGS2004

Emergency assessment of debris-flow hazards from basins burned by the Cedar and Paradise Fires of 2003, southern California

These maps present preliminary assessments of the probability of debris-flow activity and estimates of peak discharges that can potentially be generated by debris flows issuing from basins burned by the Cedar and Paradise Fires of October 2003 in southern California in response to 25-year, 10-year, and 2-year recurrence, 1-hour duration rain storms. The probability maps are based on the application of a logistic multiple regression model that describes the percent chance of debris-flow production from an individual basin as a function of burned extent, soil properties, basin gradients, and storm rainfall. The peak-discharge maps are based on application of a multiple-regression model that can be used to estimate debris-flow peak discharge at a basin outlet as a function of basin gradient, burn extent, and storm rainfall. Probabilities of debris-flow occurrence for the Cedar Fire range between 0 and 98% and estimates of debris-flow peak discharges range between 893 and 5,987 ft3/s (25 to 170 m3/s). Basins burned by the Paradise Fire show probabilities for debris-flow occurrence between 2 and 98%, and peak discharge estimates between 1,814 and 5,980 ft3/s (51 and 169 m3/s). These maps are intended to identify those basins that are most prone to the largest debris-flow events and provide information for the preliminary design of mitigation measures and for the planning of evacuation timing and routes.

Open-File Report↗
USGS2004

Emergency Assessment of Debris-Flow Hazards from Basins Burned by the Padua Fire of 2003, Southern California

Results of a present preliminary assessment of the probability of debris-flow activity and estimates of peak discharges that can potentially be generated by debris flows issuing from basins burned by the Padua Fire of October 2003 in southern California in response to 25-year, 10-year, and 2-year recurrence, 1-hour duration rain storms are presented. The resulting probability maps are based on the application of a logistic multiple-regression model (Cannon and others, 2004) that describes the percent chance of debris-flow production from an individual basin as a function of burned extent, soil properties, basin gradients, and storm rainfall. The resulting peak discharge maps are based on application of a multiple-regression model (Cannon and others, 2004) that can be used to estimate debris-flow peak discharge at a basin outlet as a function of basin gradient, burn extent, and storm rainfall. Probabilities of debris-flow occurrence for the Padua Fire range between 0 and 99% and estimates of debris-flow peak discharges range between 1211 and 6,096 ft3/s (34 to 173 m3/s). These maps are intended to identify those basins that are most prone to the largest debris-flow events and provide information for the preliminary design of mitigation measures and for the planning of evacuation timing and routes.

Open-File Report↗
USGS2003

Assessment of potential debris-flow peak discharges from basins burned by the 2002 Missionary Ridge fire, Colorado

These maps present the results of assessments of peak discharges that can potentially be generated by debris flows issuing from the basins burned by the Missionary Ridge fire of June 9 through July 14, 2002, near Durango, Colorado. The maps are based on a regression model for debris-flow peak discharge normalized by average storm intensity as a function of basin gradient and burned extent, and limited field checking. A range of potential peak discharges that could be produced from each of the burned basins between 1 ft3/s (0.03 m3/s) and 6,446 ft3/s (183 m3/s) is calculated for the 5-year, 1-hour storm of 0.80 inches (20 mm). Potential peak discharges between 1 ft3/s (0.03 m3/s) and >8,000 ft3/s (227 m3/s) are calculated for the 25-year, 1-hour storm of 1.3 inches (33 mm) and for the 100-year, 1-hour storm of 1.8 inches (46 mm). These maps are intended for use by emergency personnel to aid in the preliminary design of mitigation measures, and for the planning of evacuation timing and routes.

Open-File Report↗
USGS2003

Assessment of potential debris-flow peak discharges from basins burned by the 2002 Coal Seam fire, Colorado

These maps present the results of assessments of peak discharges that can potentially be generated by debris flows issuing from the basins burned by the Coal Seam fire of June and July 2002, near Glenwood Springs, Colorado. The maps are based on a regression model for debris-flow peak discharge normalized by average storm intensity as a function of basin gradient and burned extent, and limited field checking. A range of potential peak discharges that could potentially be produced from each of the burned basins between 1 ft3/s (0.03 m3/s) and greater than 5,000 ft3/s (>141 m3/s) is calculated for the 5-year, 1-hour storm of 0.80 inches (20 mm). The 25-year, 1-hour storm of 1.3 inches (33 mm). The 100- year, 1-hour storm of 1.8 inches (46 mm) produced peak discharges between 1 and greater than 8,000 ft3/s (>227 m3/s). These maps are intended for use by emergency personnel to aid in the preliminary design of mitigation measures, and the planning of evacuation timing and routes.

Open-File Report↗
USGS2003

Emergency Assessment of Debris-Flow Hazards from Basins Burned by the Grand Prix and Old Fires of 2003, Southern California

These maps present preliminary assessments of the probability of debris-flow activity and estimates of peak discharges that can potentially be generated by debris flows issuing from basins burned by the Old and Grand Prix Fires of October 2003 in southern California in response to the 25-year, 10-year, and 2-year recurrence, 1-hour duration rain storms. The probability maps are based on the application of a logistic multiple regression model that describes the percent chance of debris-flow production from an individual basin as function of burned extent, soil properties, basin gradients and storm rainfall. The peak discharge maps are based on application of a multiple-regression model that can be used to estimate debris-flow peak discharge at a basin outlet as a function of basin gradient, burn extent, and storm rainfall. Probabilities of debris-flow occurrence range between 0 and 85% and estimates of debris flow peak discharges range between 460 and 5,900 ft3/s (13 to 167 m3/s). These maps are intended to identify those basins that are most prone to the largest debris-flow events and provide critical information for the preliminary design of mitigation measures and for the planning of evacuation timing and routes.

Open-File Report↗
USGS2003

Emergency Assessment of Debris-Flow Hazards from Basins Burned by the Piru, Simi, and Verdale Fires of 2003, Southern California

These maps present preliminary assessments of the probability of debris-flow activity and estimates of peak discharges that can potentially be generated by debris-flows issuing from basins burned by the Piru, Simi and Verdale Fires of October 2003 in southern California in response to the 25-year, 10-year, and 2-year 1-hour rain storms. The probability maps are based on the application of a logistic multiple regression model that describes the percent chance of debris-flow production from an individual basin as a function of burned extent, soil properties, basin gradients and storm rainfall. The peak discharge maps are based on application of a multiple-regression model that can be used to estimate debris-flow peak discharge at a basin outlet as a function of basin gradient, burn extent, and storm rainfall. Probabilities of debris-flow occurrence for the Piru Fire range between 2 and 94% and estimates of debris flow peak discharges range between 1,200 and 6,640 ft3/s (34 to 188 m3/s). Basins burned by the Simi Fire show probabilities for debris-flow occurrence between 1 and 98%, and peak discharge estimates between 1,130 and 6,180 ft3/s (32 and 175 m3/s). The probabilities for debris-flow activity calculated for the Verdale Fire range from negligible values to 13%. Peak discharges were not estimated for this fire because of these low probabilities. These maps are intended to identify those basins that are most prone to the largest debris-flow events and provide information for the preliminary design of mitigation measures and for the planning of evacuation timing and routes.

Open-File Report↗
USGS2002

Emergency assessment of potential debris-flow peak discharges, Coal Seam fire, Colorado

These maps present the results of assessments of peak discharges that can potentially be generated by debris flows issuing from the basins burned by the Coal Seam fire of June and July 2002, near Glenwood Springs, Colorado. The maps are based on a regression model for debris-flow peak discharge normalized by average storm intensity as a function of basin gradient and burned extent, and limited field checking. A range of potential peak discharges that could potentially be produced from each of the burned basins between 1 ft 3 /s (0.03 m 3 /s) and greater than 5,000 ft 3 /s (>141 m 3 /s) is calculated for the 5-year, 1-hour storm of 0.80 inches (20 mm). The 25-year, 1-hour storm of 1.3 inches (33 mm). The 100- year, 1-hour storm of 1.8 inches (46 mm) produced peak discharges between 1 and greater than 8,000 ft 3 /s (>227 m 3 /s). These maps are intended for use by emergency personnel to aid in the preliminary design of mitigation measures, and the planning of evacuation timing and routes.

Colorado↗
USGS1998

A method for producing digital probabilistic seismic landslide hazard maps: An example from the Los Angeles, California, area

The 1994 Northridge, California, earthquake is the first earthquake for which we have all of the data sets needed to conduct a rigorous regional analysis of seismic slope instability. These data sets include (1) a comprehensive inventory of triggered landslides, (2) about 200 strong-motion records of the mainshock, (3) 1:24,000-scale geologic mapping of the region, (4) extensive data on engineering properties of geologic units, and (5) high-resolution digital elevation models of the topography. All of these data sets have been digitized and rasterized at 10-m grid spacing in the ARC/INFO GIS platform. Combining these data sets in a dynamic model based on Newmark's permanent-deformation (sliding-block) analysis yields estimates of coseismic landslide displacement in each grid cell from the Northridge earthquake. The modeled displacements are then compared with the digital inventory of landslides triggered by the Northridge earthquake to construct a probability curve relating predicted displacement to probability of failure. This probability function can be applied to predict and map the spatial variability in failure probability in any ground-shaking conditions of interest. We anticipate that this mapping procedure will be used to construct seismic landslide hazard maps that will assist in emergency preparedness planning and in making rational decisions regarding development and construction in areas susceptible to seismic slope failure.

California↗
USGS1996

Site-response maps for the Los Angeles region based on earthquake ground motions

Ground-motion records from aftershocks of the 1994 Northridge earthquake and main-shock records from the 1971 San Fernando, 1987 Whittier Narrows, 1991 Sierra Madre, and 1994 Northridge earthquakes are used to estimate site response in the urban Los Angeles, California, area. Two frequency bands are considered, 0.5-1.5 Hz and 2.0-6.0 Hz. Instrument characteristics prevented going to lower frequencies, and frequencies above 6.0 Hz are less important to the building inventory. Site response determined at the instrumented locations is associated with the surficial geology and contoured to produce a continuous spatial estimation of site response. The maps in this report are preliminary and will evolve as more data become available and more analysis is done.

California↗