Title

The Day the Earth Moved: Detecting Evidence of Earthquakes

Presenter Information

Amara McBride

Document Type

Oral Presentation

Location

SURC Ballroom A

Start Date

17-5-2012

End Date

17-5-2012

Abstract

In 1989, the 7.1 M Loma Prieta earthquake (LPEQ) occurred on a previously locked section of the San Andreas fault system (SAF) in northern California resulting in more than $6 billion in damages, 63 fatalities, ~4000 injuries and 12,000 homeless. Oddly, this event produced no known surface ruptures which pose problems for understanding the overall paleo-seismic history of the Loma Prieta segment of the SAF and its role assessing local seismic hazards. Comparisons between the pre- and post-LPEQ surface expressions along the Loma Prieta segment of the SAF provide new insights into the spatial and geomorphological impacts of seismic activity associated with the LPEQ. Through comparative analysis of field and desktop mapping based on hi-resolution (0.5 m) airborne light detection and ranging (LiDAR) data and digitization of pre-LPEQ fault mapping of the Loma Prieta segment of the SAF, I was able to identify and, in some cases, quantify subtle changes in the tectonic geomorphology that provide new constraints on the paleoseismology and seismic hazards associated with this portion of the San Andreas fault system. The focus of my study is a ~20 mile, strike-parallel transect along the SAF that spans the SE Mindego Hill, southern Cupertino, Castle Rock Ridge and northern Los Gatos 1:24K USGS Quadrangles. Along this transect, I was able to identify, previously unmapped landslides, growth of existing landslides, offset streams, shudder ridges, and ponded Holocene alluvium. Identification of these features will guide future paleoseismic studies and further refinement of seismic hazard models.

Poster Number

6

Faculty Mentor(s)

Caroline Whitehill

Additional Mentoring Department

Geological Sciences

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May 17th, 2:00 PM May 17th, 4:30 PM

The Day the Earth Moved: Detecting Evidence of Earthquakes

SURC Ballroom A

In 1989, the 7.1 M Loma Prieta earthquake (LPEQ) occurred on a previously locked section of the San Andreas fault system (SAF) in northern California resulting in more than $6 billion in damages, 63 fatalities, ~4000 injuries and 12,000 homeless. Oddly, this event produced no known surface ruptures which pose problems for understanding the overall paleo-seismic history of the Loma Prieta segment of the SAF and its role assessing local seismic hazards. Comparisons between the pre- and post-LPEQ surface expressions along the Loma Prieta segment of the SAF provide new insights into the spatial and geomorphological impacts of seismic activity associated with the LPEQ. Through comparative analysis of field and desktop mapping based on hi-resolution (0.5 m) airborne light detection and ranging (LiDAR) data and digitization of pre-LPEQ fault mapping of the Loma Prieta segment of the SAF, I was able to identify and, in some cases, quantify subtle changes in the tectonic geomorphology that provide new constraints on the paleoseismology and seismic hazards associated with this portion of the San Andreas fault system. The focus of my study is a ~20 mile, strike-parallel transect along the SAF that spans the SE Mindego Hill, southern Cupertino, Castle Rock Ridge and northern Los Gatos 1:24K USGS Quadrangles. Along this transect, I was able to identify, previously unmapped landslides, growth of existing landslides, offset streams, shudder ridges, and ponded Holocene alluvium. Identification of these features will guide future paleoseismic studies and further refinement of seismic hazard models.