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SDAG Monthly Meeting
Wednesday, March 22, 2017

Location: Giovanni's Restaurant
9353 Clairemont Mesa Blvd.
San Diego 92123
Tel: (858) 279-6700


happy hour
5:30pm -
Social hour  
Cash Bar.

Menu: Pizza-Salad Buffet. Cash bar.
6:30pm -

Cost: $30.00 for non-members, $25.00 for members, $15.00 for students. if pre-registered by the deadline, $5 extra if you did not make a reservation. Click the SDAG member checkbox on the reservation form if you are a member.

Reservations: Make your reservation online by clicking the button below no later than NOON, Monday, March 20. RESERVATIONS CANNOT BE ACCEPTED AFTER Monday at noon. Late reservations/cancellations are preferred over walk-ins or no-shows. Fees payable at the meeting or pre-pay with PayPal.
As a new payment option, there will be a phone credit card reader at the meeting.

If you are a current SDAG member and are not getting e-mail announcements,
make sure the SDAG secretary has your correct e-mail address.

7:30pm -

Speaker: Laurie Racca, PG

"Understanding the Licensure Laws and Responsibilities of the Licensee"

Abstract: The California Board for Professional Engineers, Land Surveyors, and Geologists (BPELSG) is charged with safeguarding the life, health, property, and public welfare by regulating the practices of professional engineering, land surveying, geology, and geophysics. Knowledge of the laws and regulations that govern licensed professionals in California is essential to ensuring that critical work is done by qualified professionals.

BSPELG is inviting you to have an informal "round table discussion" focused on the recent changes to the licensing laws and regulations (2017 update), a review of key concepts regarding professional licensure, and the importance of mentoring young professionals. Some of the topics that we will cover include: promoting understanding of the difference between a practice licensing act (such as the PG license) and a title licensing act (such as the CEG of CHG specialty licenses), keeping our licensing tests current with the state of practice by the different licensees, and keeping our procedures and statutory obligations current too. It is our belief that we need more frequent feed-back from stakeholders about these issues as well as greater participation by our licensees for activities pursued by the Board that impact our respective futures.

Laurie Racca, PG, is the Senior Registrar for Geology and Geophysics at BSPELG. Her 25+ years of experience includes working in private environmental and geotechnical consulting, providing regulatory agency oversight of large military and civilian environmental cleanups for the Department of Toxic Substances Control, and investigating fraud, waste and abuse as part of the Office of Enforcement at the State Water Resources Control Board.

Speaker: Luke Weidman (Credit to Jillian Maloney and Tom Rockwell)

"San Diego Earthquake Hazard: Geotechnical Synthesis"

Abstract: With a population of ~1.3 million, the City of San Diego is the third largest city in California, and it is traversed by the Holocene-active Rose Canyon Fault Zone (RCFZ). The Rose Canyon Fault is a strike-slip fault with a slip rate of 1-2 mm/yr and the potential to produce a M6.9 event. This project focuses on the strands of the RCFZ that traverse through the downtown area, which is the economic center of the city. The seismic hazard of the RCFZ has a direct impact on development in and around the city via the Alquist-Priolo Earthquake Fault Zoning Act, which regulates locations of structures for human occupancy. As a result, geotechnical firms in San Diego have been conducting many private, small-scale studies and investigations of the local fault architecture since the 1980s and have amassed an impressive amount of data. However, each report is plot or parcel specific and, at most, will only reference data from neighboring parcels. As there exists no resource where all of the data can be studied at once, reports are commonly studied independently. This project synthesizes the existing geotechnical data into a comprehensive geodatabase in an effort to show the current fault geometry within the city and provide insight to the evolution of the RCFZ.

Historically, geotechnical companies are hesitant to share results of fault studies and field investigations with each other, as the data is proprietary. Recently, however, several geologists and engineers within the professional community have called for a combined resource and many of San Diego's geotechnical firms have contributed data, including Geocon, Kleinfelder, Leighton & Associates, CTE, and URS/AECOM. This project compiles the data as a means to contribute to and improve upon the community fault model and give the city an accurate model for use in updating its seismic safety element. The geodatabase also aids the science community by helping to establish the variety of fault characteristics and complexities along strike, illuminate recurrence intervals or patterns of multi-segment ruptures, and provide evidence for long term slip rate. To date, we have collected over 500 geotechnical reports, and locations of all trenches, borings, and CPT soundings are being compiled in a GIS database.

Speaker: Stephen Campbell (Credit to Sarah Gray, James Whinney, Carlos Ramos-Scharron, Sean Campbell & Matthew C. LaFevor

"Watershed Runoff and Sediment Resuspension: Factors Affecting Turbidity and Sedimentation in Bays with Coral Reefs, St. John, USVI"

Abstract: In the US Virgin Islands (USVI), land-based (terrigenous) sedimentation has been identified as a major cause of coral stress. Development, such as the building of unpaved roads in steep coastal watersheds, has increased sediment yields and marine terrigenous sedimentation by up to an order of magnitude above background levels. When ephemeral streams are activated during storm events on St. John, the transport land-based sediment to the marine environment results in the formation of sediment plumes. Once the plumes dissipate and the sediment is deposited on the seafloor, resuspension of benthic sediments can further increase turbidity and deposition. However, isolating the relative contributions of runoff and resuspension to turbidity and deposition using conventional sediment trap monitoring has proven difficult. Here we describe the spatial and temporal variability of marine sediment dynamics in response to runoff and resuspension events in St. John, and compare time-integrated (~26-day) sediment trap monitoring to high-resolution (10-min) nephelometer monitoring approaches. Between late July 2013 and January 2014, nephelometers were deployed beside sediment traps at three reef and five shoreline sites next to ephemeral stream out-falls equipped with a water level sensor (10-min resolution) and peak crest gauges (~13-day resolution). At each instrument site benthic sediment samples were collected every ~26 days. Monthly mean sediment trap accumulation rates and nephelometer data were strongly correlated.

While runoff events resulted in high-magnitude spikes in turbidity and deposition, which were up to 900 and 17,000 times background, respectively, they were short-lived (hours). Resuspension-induced spikes in turbidity and deposition were lower in magnitude but of longer duration (days- weeks), particularly at sites with finer-grained benthic sediments, and were associated with increased wave height during low tides. While the relative contribution of runoff and resuspension to turbidity and deposition were spatially variable between our study sites, overall, resuspension contributed at least 7 times more to turbidity and 3 times more deposition than runoff during the 2013 rainy season. Though previous studies have measured marine sedimentation over months-centuries in St. John, no studies have monitored turbidity or the relative contributions to turbidity and deposition from runoff and resuspension at the time scale of minutes-days. Understanding the relative contribution of runoff vs. resuspension to marine turbidity and deposition is important to effectively man-age land-based sedimentation, marine development, as well as evaluate the effectiveness of watershed restoration programs which aim to reduce marine terrigenous sedimentation.

Speaker: Carlos Anguiano

"Archaeointensity Study on Armenian Archaeological Pottery Sherds from ~6000-1000 BCE"

Abstract: Documenting the behavior of the ancient geomagnetic field is crucial to understanding the dynamics that occur within the bowels of the Earth, as well as the field's interaction with the biosphere, atmosphere, and solar radiation. This is naturally carried out by magnetic iron bearing minerals that are able to record the intensity and direction of Earth's magnetic field over billions of years. Importantly, such records are retrieved by paleomagnetists who seek to improve the spatial distribution and temporal span of paleointensity data. Compiling new data from different regions and periods is necessary to improve the global database, allowing one to develop new field models essential for studying the geomagnetic field. In this study, archaeological pottery sherds from different sites in Armenia, a region that lacks absolute paleointensity data, were used to determine the intensity of Earth's magnetic field during the Stone Age, Bronze Age, and Iron Age. Specifically, the IZZI protocol, a successful and robust paleointensity experiment was used. This optimal stepwise heating experiment allows one to detect any sort of unreliable data, such as non-ideal behavior caused by alteration and failure of the law of reciprocity. A total of seventy-two specimens, three specimens per sample (twenty-four samples), were subjected to paleointensity experiment, followed by careful assessment using a strict selection criteria. Twenty-four specimens exhibited ideal behavior, which makes us confident of obtaining a number of robust paleointensity data with further study from these sites. Our new results will provide effective constraints on the variation of the geomagnetic field intensity between 6000-1000 BCE within Armenia.

Speaker: Nick Lau

"New Geodetic Measurements of Crustal Deformation in Southern California from the Sentinel-1 Mission"

Abstract: The new Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) mission, launched the European Space Agency in April 2014, demonstrates unprecedented spatial coverage and fine temporal resolution, enabling precise estimation of secular and transient crustal deformation. Interferometric measurements provide a description of the displacements on the Earth's surface relative to the satellite's line of sight. In this study, I process a large data set comprised of interferograms from multiple overlapping descending and ascending InSAR tracks to form a mosaic of displacement measurements covering all of Southern California. We can then isolate low-amplitude deformation signals by estimating and removing contributions from the ionosphere and troposphere, and compute mean line-of-sight crustal velocities over the two-year period between 2015 and 2017. Average line-of-sight velocities from different InSAR look angles can be combined with independent measurements of horizontal surface velocities obtained from the continuous Global Positioning System (cGPS) network to estimate a three-dimensional velocity field. A complete description of surface motions provided by the combination of these data sets would enhance our understanding of the crustal deformation processes in the seismically active regions of Southern California.

Upcoming SDAG meetings - 2017

April 19: John Minch - The Greater Hanshin (Kobi) Earthquake

May 17: John Wallace and Pat Shires - Sycamore-Ranchito Landslide - Santa Barbara

June 21: Jorge Ledesma Baja California, Mexico

Meetings are usually scheduled for the 3rd Wednesday evening of the month. Meeting information on this website is normally updated the second week of the month.

If you have any information, announcements, ads or suggestions for an upcoming newsletter, please submit it to Ken Haase, (2017 SDAG Secretary). Any news regarding upcoming events that may be of interest to the Association or news of your business can be submitted. The submittal deadline for the next SDAG newsletter is the last Friday of the month.
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