Monday, December 27, 2021

Eminent earthquake scientists: Clarence Allen and Robert Wallace oral histories

For some "light reading" over the winter break, I have enjoyed a read of oral histories of Clarence Allen (Caltech) and Robert Wallace (USGS).
EARTHQUAKES, MINERALS AND ME: WITH THE USGS, 1942-1995 by Robert E. Wallace; Oral History Interviews With Stanley Scott; USGS Open-File Report 96-260

Connections EERI Oal History Series: Clarence Allen with interviewer Stanley Scott
CLARENCE R. ALLEN (1925-2021) INTERVIEWED BY DAVID A. VALONE Caltech archives. This latter one has a bit more about Caltech and is slightly less polished than the first.

Maybe I at times too sentimental, but I found these personal and scientific histories throught provoking and inspiring, not only for their tellings of important steps in the history of earthquake science and service, but also for their modest, laconic, and matter of fact story telling. I am also fortunate to have substantial memories of interacting with both of them personally and also of the transition at the end of their careers and the beginning of mine (I entered graduate school at Stanford University in Fall 1989). I also appreciate the effort of EERI to accumulate those and other oral histories.

One thing that comes to mind is that it would be nice to include some histories from women who have contributed in these areas. I will work on that for a future blog post.

Bob Wallace was inspiring as an earthquake geologist. I followed some of his work quite closely as I shared an obsession with geomorphic indicators of faulting, although certainly with less of an impact...
Just a couple of examples from his papers:

  1. 1949 - Wallace, R. E., Structure of a portion of the San Andreas rift in southern California: Bulletin of the Geological Society of America, v. 60, n. 4, p. 781-806.. This is cited as one of the earliest focused mapping efforts along the San Andreas Fault. He mapped substantial offset along the San Andreas Fault and also worried about the fault zone core and interactions of the drainage network with the fault zone. At one point, I colored the detailed map to appreciate it better.
  2. 1968 - Wallace, R. E., Notes on stream channels offset by the San Andreas fault, southern Coast Ranges, California, in Dickinson, W. R., and Grantz, Arthur, eds., Proceedings of conference on geologic problems of San Andreas fault system: Stanford University Publications in Geological Science, v. 11, p. 6-21.. This was a landmark in my mind as he noted offsets along the San Andreas Fault in the Carrizo Plain as indicators of short and longer term indicators of recurrent fault slip. It was in a somewhat difficult to find publication. But, being around Stanford University (and having to move out of the Geology Corner after the Loma Prieta Earthquake), there were numerous copies to be found. Figures 6 and 7 of the histograms of numbers of channels with certain offset sizes was something we followed up on a fair bit.
  3. 1990 - Wallace, R. E., (editor) The San Andreas Fault System, California: U. S. Geological Survey Prof. Paper 1515, 283 p.. This was his magnum opus. I was lucky once to meet him in his office at USGS Menlo Park and he asked if I had a copy yet. I did not even though I had stared at it. He reached into his filing cabinet and gave me his copy! I should have asked him to sign it or something but I certainly treasure that copy. It has now been rebuilt a few times...
  4. 1992 - Wallace, R. E., Ground-squirrel mounds and patterned ground along the San Andreas fault in central California: U. S. Geological Survey, Open-file report n.91-149, p. 1-21.. This was a modest contribution, but I had a couple of conversations with him about it as we shared our enthusiasm for the Carrizo Plain. In his related GSA presentation, he even mentioned me as someone who might pick it up! Scared the crap out of me. We never really did a systematic effort on this but it remains a fascinating problem. I talk about it with people every time I get to the Carrizo Plain.
THere is a lot more to say and remember about Bob Wallace. My memories of him are also tied to Kerry Sieh who worked with Bob and honored him by naming the offset channel he explored in the 1968 paper "Wallace Creek". How many times have I read the Sieh and Jahns 1984 paper: Sieh, K. E., and Jahns, R. H. (1984). Holocene activity of the San Andreas fault at Wallace Creek, California. Geological Society of America Bulletin, 95, 883–896.. We even revisited this in our 2019 paper.

One of my San ANdreas Fault tour videos over the Carrizo Plain. Hillshades produced by me from the B4 project at OpenTopography.

I did not interact with Clarence Allen as much as I did with Bob Wallace, but I did have a few nice conversations with him. I think he was more serious in the conversations than I was. They main ones were when I was thinking about going to Caltech to work with Kerry Sieh. Clarence and I talked about science, but also about trout fishing. I regret never taking him up on an invite to fish in the San Bernardino Mountains. I think my father had fished some of the same places there around and below Lake Arrowhead or Big Bear Lake.
Two papers among many I would like to highlight from Clarence:

  1. Allen, C. R. (1968). The tectonic environments of seismically active and inactive areas along the San Andreas fault system. Proceedings of Conference of Geologic Problems of San Andreas Fault System, 5(1496), 70–80.. This stands as an important first order characterization of the San Andreas Fault system and the recognition that the geology was an important control on the current behavior of the system. I have used Figure 1 here and there over the years when I kick of talks on the San Andreas Fault.
  2. Geological Criteria for Evaluating Seismicity: Address as Retiring President of The Geological Society of America, Miami Beach, Florida, November 1974 CLARENCE R. ALLEN GSA Bulletin (1975) 86 (8): 1041–1057. This is a classic that helps to introduce the concepts of earthquake geology and the value of the geologic record in the study of recently active faults.
My recent attempt to follow Prof. Allen's ideas about the San Andreas Fault (some edits on the caption from Mike Oskin; we made this as a prototype for a SCEC request). The geology of the plate boundary shows the SAFS progressively dismembering the former subduction system (as indicated by the paired Mesozoic metamorphic--green and granitic--red rocks) (; upper panel). This framework is a first order control on the behavior of the system (lower panel): active faults (USGS and CGS 2021) and M>4 seismicity ( overlain on the GMRT (Ryan, et al., 2009).

Sunday, December 5, 2021

AI art: what does " Tectonic Geomorphic San Andreas Fault" look like?

I saw a link to on twitter and people were posting what they got out of using their research or dissertation titles as a prompt. It is pretty amazing.

I gave it a try. My dissertation was entitled "Coupled Tectonic Deformation and Geomorphic Degradation along the San Andreas Fault System". I tried that as well as a shorter version "Tectonic Geomorphic San Andreas Fault" with a couple of different styles. I have to ponder the results. Some of the other examples work well when there is an object more recognizeable (such as a bird or T-cell), or somehow I need to give it a more interesting prompt. But the results are interesting. I like the trading card format.

Later on, I saw something about how the company could sell the "art" as NFTs but I guess I am not too worried about it.

Wednesday, December 1, 2021

Remembering Paul J. Umhoefer

I recently wrote this memorial for the Geological Society of America Structural Geology and Tectonics Division (which I am now beginning my stint as chairman or soon will). That is the reason for the first person plural.

We heard with great sadness and shock of the passing of our dear friend and colleague Professor Paul J. Umhoefer (Northern Arizona University) in late November 2021. Some of us saw him at the 2021 GSA meeting and to lose him so soon after weighs on us.

Paul Umhoefer was a great scientist, mentor and teacher, and servant to his professional community and department. He was well known for his research in tectonics, basin analysis, structural geology with carefully collected field data from the western US, Baja California, and Anatolia.

Much of his research was done in close collaboration with his many students at NAU. He was a strong mentor who guided many of those projects to publication and the students went on to success, especially in academia and the petroleum and geo-environmental industries. His professional colleagues appreciated his guidance and invitation to join interesting projects.

Paul was a tireless leader in the geoscience community. He helped to propel important community initiatives, including Margins/GeoPrisms. He not only contributed synthetic ideas but was an integrator and conciliator. He was an effective chair of his department helping guide it in a time of important growth. We are grateful for this leadership in the Geological Society of America Structural Geology and Tectonics Division where he was a long time active member, proponent of GSA fellows, and had recently completed the arc of leadership of the division.

Along with his tireless work ethic, Paul was enthusiastic and gregarious with a big smile and a joke for his friends and colleagues delivered in his deep creaky voice. He loved to talk about ideas: geoscience, politics, sports.

We counted on seeing him again soon. We are sorry to lose him and our thoughts are with his family and close friends.

Paul Umhoefer in one of his favorite places: the southern Baja California coast line with uplifted terraces and Tertiary sedimentary and volcanic rocks awaiting his attention (Arrowsmith photo, 2005)

--Ramon Arrowsmith (incoming Division Chair) on behalf of the Geological Society of America Structural Geology and Tectonics Division