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and groundwater geology since 1957

May Meeting of the Southern California Chapter

***Tuesday, May 8, 2018***

Greetings AEG Southern California Chapter Member
We are fortunate to host the AEG/GSA 2017/2018 Jahns Lecturer, Dr. John Wakabayashi, visiting southern California and presenting at our AEG Southern California chapter meeting on Tuesday, May 8th. I hope you will join us for this special event to be held at Victorio's Ristorante, in North Hollywood.

Dr. Wakabayashi will be presenting at other venues during his southern California Visit. If you can't make the Tuesday meeting you can catch him at:

California State Polytechnic University, Pomona, on Monday May 7th at 6:30 pm. Please contact Ernie Roumelis at for additional information. His presentation at Cal Poly Pomona will be on Geomorphic evolution and Cenozoic tectonics of the Sierra Nevada.

California State University, San Bernardino, the evening of Wednesday May 9th. Please contact Kerry Cato at for additional information. The presentation at CSUSB will also be on Strike Slip Stepovers.

Please see below for meeting information including whom to RSVP.

Topic: "Evolution of step-overs and bends along strike-slip faults: Implications for seismic hazards assessment"

Speakers: Dr. John Wakabayashi
Professor, Department of Earth and Environmental Sciences, California State University, Fresno, California

Location: Victorio's Ristorante
10901 Victory Boulevard
North Hollywood, CA 91606

Date/Time: Tuesday, May 8, 2018
5:45pm - Social Hour
6:45pm - Dinner
7:45pm - Program

Cost: $40 per person with reservations in advance for AEG members,
$45 without reservations (at the door) and non-members,
$25 for students with a valid student ID.

Reservations: Please email Darrin Hasham at: or call (909) 380-3289
Please make reservations prior to 12:00 noon, Monday, May 7th.
Step-overs along strike-slip faults have been traditionally considered to grow in size and cumulative slip accommodation as more slip accrues on the parent strike-slip fault. In such a model with greater slip, a pull-apart basin grows larger and deeper and a restraining step-over generates more uplift and exhumation. Inspection of step-overs of the San Andreas fault system suggests that step-overs migrate with respect to material formerly within them. This requires progressive formation of new transfer structures in the direction of migration. This process appears to operate from the meters/tens of meters scale of sag ponds and small push-up blocks to multi-kilometer scale basins and uplifted welts, with the Mendocino Triple Junction region being perhaps the largest scale structure of this sort proposed. Migrating step-overs result in inversion at all scales from thrusted sag pond deposits to inverted large-scale sedimentary basins. This style of step-over migration complicates assessment of long-term displacement on strike-slip faults because the zone of displacement is commonly much broader than the active strand, and this also applies to more recent displacement and earthquake history. Accordingly, siting of paleoseismic trenches needs to address this potential complexity to optimally capture the full fault slip rate (for fault-parallel trenches) and most complete earthquake histories (for fault-crossing trenches). In addition, the migrating step-over mechanism leads to propagation of some fault stands and the dying out of activity on others. This may result in some faults with a large cumulative displacement that have little or no late Quaternary activity whereas some immature strands with little geomorphic expression may accommodate significant slip rate.
Speaker Biography
Dr. John Wakabayashi, is the 2017-2018 Richard H. Jahns Distinguished Lecturer in Applied Geology. The Jahns Distinguished Lectureship, established in 1988, is sponsored by the Association of Environmental and Engineering Geologists and the GSA Engineering Geology Division. Its purpose is to provide funding for distinguished engineering geologists to present lectures at colleges and universities to increase awareness of students about careers in engineering geology. The lectureship is named in honor of Dr. Richard H. Jahns (1915- 1983), an engineering geologist who had a diverse and distinguished career in academia, consulting and government.

John Wakabayashi is a San Francisco Bay Area native who moved to Fresno in 2005 to begin his academic career as a geology professor at California State University, Fresno. He received his B.A. in Geology in 1980 from UC Berkeley, and his PhD in Geology in 1989 from UC Davis. He is a Professional Geologist (California) and a Fellow of the Geological Society of America.

John incorporated academic research of his own and others into his project work, trying to bridge the academic-applied geology gap from the standpoint of a practitioner. After becoming an academic he has continued his efforts to bridge this gap, with realization that the vast majority of geology professors have never been employed in the engineering and environmental geology profession that most geology graduates will work in. He incorporates both his professional and research experience into his teaching to better prepare students for professional careers, as well as providing a foundation for students who wish to undertake graduate study.

His research has resulted in 82 published papers and over 100 abstracts tied to presentations at major geoscience meetings. The breadth of his research has broadened rather than narrowed over time. In spite of the wide range of research interests, the geology of that beguiling train wreck of rocks known as the Franciscan Complex of coastal California remains his chief interest and the many aspects of mélanges have become his focus since 2009.

At Fresno State he teaches non-major introductory geology, geology major undergraduate courses in petrology, geomorphology, and structural geology, graduate courses on active tectonics/seismic hazard analysis and orogenic belt tectonics, and his bread-and-butter undergraduate course in advanced geologic field mapping (he makes his students map Franciscan along with landslides, flights of stream terraces and some potentially active faults). He has supervised or is supervising many graduate and undergraduate student researchers, and this includes a number of students from outside of Fresno State.

Outside of geology and beer (an amateur brewer since 1994), he is probably best known for his experience trout fishing in the backcountry (must be hiked to) of California, having launched casts into over 750 different lakes, about 700 of these in the Sierra Nevada; 2015 was an especially good summer. His strength and fitness routine that prepares him for his fieldwork and recreational hiking (and burns off some of the beer), as well as holding his body together for his return to playing basketball, has also gained some notoriety. This routine includes excessively long plank sessions and multiple repetitions of muscle ups.