I provided a choice of seven Jahns Lectures. By far the most popular were the “Comforts” and “Elephants” lectures.
The Least You Should Know About Characterizing Geological Chaos: Bimrocks (block-in-matrix rocks) are geologically complex mixtures of rocks and soils, such as melanges, fault rocks, and weathered rocks. Bimrocks present major challenges to geopractitioners because successful and economical characterizations of rock/soil mixtures are frustrated by their geological, spatial and mechanical variability. This Lecture presents broad concepts on characterization, design and construction in bimrocks that have been provocative, yet useful, to geopractitioners around the world.
The Comforts of Ignorance and the Benefits of Arrogance – Lessons of the Failure Kind for the Geopractitioner: Ignorance and arrogance are all too common in the design professions. It is comforting to not know what one does not know. And, there are benefits to being arrogant: why waste time on having a colleague check your work if you know what you are doing? Why go through the pain of further education or professional development? Why should engineering geologists talk to geotechnical engineers (and vice versa)? After all: “I know enough geowhatever to get by.” But ignorance leads to blissful mistakes and arrogance results in occasional spectacular, famous and expensive failures. In this lecture a few lessons are offered, particularly to the engineering geologist/geotechnical engineer/environmental scientist who thinks he/she knows it all.
Of Elephants, Earthquakes, Caves and Hot Rock – Recent Geological Engineering Adventures: The Lecturer, a Civil Engineer/Engineering Geologist, describes the technical background of a Geological Engineer in the context of elephants. The broad technical skills sets of most Geological Engineers are excellent for the two-way translations of geology and engineering. Three recent case histories provide examples: A summary of the Geological Engineering observations from a reconnaissance commissioned to observe damage resulting from the October 2006 Hawaii earthquake; the very challenging Forbes Cave project in Hawaii, a rare story of a geopractitioner becoming very dirty as a Court-Appointed Expert advising on lava tube cave stability and recovering a buried collection of unique Hawaiian cultural artifacts; and, the Geological Engineering insight required for overall geoengineering characterization of terrain hazards at the Lihir gold mine in Papua New Guinea, located in a geothermally active, collapsed volcanic caldera.
Something to Chew on- Rock is More Nutritious than Dirt: A medley of geoengineering presentations is scrambled to provide oft-neglected supplementary nourishment to soils engineers afforded by rock engineering. Ingredients in the Lecture may include (at the whim of the chef): an analysis of high cut slopes, and characterization of weak rock masses using the Hoek-Brown Failure Criterion, “layered” on the basis of depth varying Geological Strength Indexes; description of the simple Geological Engineering basis for confidence in the rock mass stability of the walls of lava tubes caves during retrieval of a buried collection of unique Hawaiian cultural artifacts; and, why you should care about melanges and other block-in-matrix rocks (bimrocks).
An Introduction to the Use of Ground-Based Stereo Photography in Geopractice: In some situations three-dimensional (3D) perception is critical to efficient and accurate geological/geotechnical investigation. Taking and exploiting ground-based stereo photographs for personal use and geology and engineering consulting is easy and inexpensive. Stereo (3D) photos preserve records of site conditions for use in analysis back at the office, and allow a clear visual depiction of the site to audiences such as clients and juries. Examples of ground-based stereo images of terrain, landslides, gullies, distressed structures, and other features—as used in project-related analyses and presentations—demonstrate the considerable advantages in collecting and viewing site information as stereo images. Stereo glasses will be provided.
Forensic Investigation of the Sea Cliff Incident, an Urban Catastrophe: Shortly after midnight on December 11, 1995, storm water started to leak from a century-old 6-foot brick sewer underlying the prestigious Sea Cliff neighborhood in San Francisco. The leakage eroded vulnerable dune sand soil to create a pit that grew uncontrollably to over 250 feet wide and 40 feet deep. Shortly after dawn, a multi-million dollar home and portions of other properties fell into the pit, events that were broadcast by TV world-wide. Discharge from the sewer continued for several hours, resulting in the undermining of other homes, destruction of part of the Presidio National Park, and eventual overflow of sewage more than two miles away, across the Great Highway and Ocean Beach, into the Pacific Ocean. Dr. Medley, the Principal Investigator for the investigation, shares findings and the lessons learned from the failure.
” “Shoot! It’s Been Delightful!” Reflections and Snapshots from a 40-year GeoOdyssey: With this typical enthusiastic comment from the late Professor Richard H. Jahns, Dr. Medley describes the highlights of his own unusual career as a prospector, geological engineer, geotechnical engineer and vagabond – a random walk of major life lurches, with several engaging detours. Pausing en route, Dr Medley offers some observations on the current state of engineering geology education and professional practice with (likely provocative) suggestions to academics, students and young professionals.