ABSTRACT: Seismic, Side-Scan Survey, Diving, and Coring Data Analyzed by a Macintosh II^TM Computer and Inexpensive Software Provide Answers to a Possible Offshore Extension of Landslides at Palos Verdes Peninsula, California

R. F. Dill, J. E. Slosson, D. B. McEachen

A Macintosh II^TM computer and commercially available software were used to analyze and depict the topography, construct an isopach sediment thickness map, plot core positions, and locate the geology of an offshore area facing an active landslide on the southern side of Palos Verdes Peninsula, California. Profile data from side scan sonar, 3.5 kHz, and Boomer subbottom, high-resolution seismic, diving, echo sounder traverses, and cores--all controlled with a mini Ranger II navigation system--were placed in MacGridzo^TM and WingZ^TM software programs. The computer-plotted data from seven sources were used to construct maps with overlays for evaluating the possibility of a shoreside landslide extending offshore.

The poster session describes the offshore survey system and demonstrates the development of the computer data base, its placement into the MacGridzo^TM gridding program, and transfer of gridded navigational locations to the WingZ^TM data base and graphics program. Data will be manipulated to show how sea-floor features are enhanced and how isopach data were used to interpret the possibility of landslide displacement and Holocene sea level rise. The software permits rapid assessment of data using computerized overlays and a simple, inexpensive means of constructing and evaluating information in map form and the preparation of final written reports. This system could be useful in many other areas where seismic profiles, precision navigational locations, soundings, di er observations, and core provide a great volume of information that must be compared on regional plots to develop of field maps for geological evaluation and reports.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990