追忆唐·亨伯格教授:地震学大师和非凡导师(英汉对照)

Chapter 1. Donald V. Helmberger，s art and science of waveforms Charles Langston* Center for Earthquake Research and Information， University of Memphis， Memphis， TN 38152， USA Correspondence:clangstnamemphis.edu Citation:Langston CA (2022）. Donald V. Helmberger’s art and science of waveforms. Earthq Sci 35(1）:3-5 doi:10.1016/j.eqs.2022.01.001 I arrived at the Caltech Seismo Lab early in May 1972. The faculty and graduate students had the run of an old mansion (Donnelly Lab） that was slightly tattered around the edges but conducive to both all-night work sessions and goofing off since it still had well-kept grounds that included a tennis court. Most of the graduate students occupied the large dining room on the first floor and we hunted out our advisors， when needed， by trying their offices around the rest of the house， checking out the tennis courts， or visiting the coffee pot in the basement. Since I arrived several months before the Fall 1972 semester， I was fortunate to be allowed to start working on graduate research. Don was assigned to be my advisor and I visited him in his second-floor office for a first encounter. He got down to business rather quickly by asking me point blank “why do you want to study geophysics?” I was totally unprepared for this question and， in fact， was probably unprepared for any other question as well. While an undergrad at Case Western Reserve， I had developed a burning hate for computer work but an intense love for geology. For some reason， I also did not like seismology， maybe because it was too esoteric， and vowed never to become a seismologist. So， I sat there stunned in front of this seismologist and finally mumbled something about wanting to study the Earth. I think Don just looked at me for a moment probably thinking that here was a guy without a whole lot of promise but that he would run me through some paces over the summer to see what would happen. My first impression of Don was that here was a real scientist doing inscrutable things that I would really like to understand. He was very young， obviously confident and a bit stand-offish， but seemed to be a straight-ahead nice guy without a big ego. After that initial check-out question there was never a time where Don treated me (or any of his other students）other than an equal colleague. I think that this kind of behavior was what made the lab an incredible learning environment. To be treated as an equal meant that a student had to work hard to catch up with the faculty to earn that place of equality， at least in our own minds. Don had me looking at seismograms that first summer. He had finished a short paper with an undergraduate intern on the arrival times of regional Pn and PL waves (York and Helmberger， 1973） and wanted to extend that project to determine crustal and upper mantle structure from the waveforms. of course， I had no idea what to do but picked up some useful skills in digitizing analog seismograms that I used later in my thesis work. It would take another 7 years to complete this program of modeling Pnl waves through his work with staff member Gladys Engen (Helmberger and Engen， 1980）. Even so， that open-ended dive into seismological research from Don’s new perspective of using waveform shapes and amplitudes has stuck with me over my entire career. While staring at the wiggles on the paper that first summer I wondered if there were other ways of recording seismic data that would give an analyst direct knowledge of the properties of the seismic waves so they could be understood much more quickly. This question stewed for many years in my own research and has resulted in some very interesting new techniques in array seismology (e.g.， Langston and Liang， 2008; Langston， 2021）. I fully attribute this to the questions that Don exposed me to that first summer. Don was too young to be considered a father figure to his students at that time. Even so， as I look back to his mentoring， it struck me that he had one characteristic that my own father displayed. That characteristic was allowing freedom. Don allowed me and his other students freedom to pursue our work wherever it led. As graduate student life settled in， Don never dictated what should be done or when it should be done， we simply (and energetically） followed the science hunt to wherever it went. This was an incredible gift which the ensuing years have validated over and over seeing how faculty at other institutions treat (or mistreat） their students. The curriculum at the Lab was unusual in that every course was “Advanced” There was no preparation with lower-level courses that you often find in other university programs. That first year Don taught Advanced Seismology 261a and shared Advanced Seismology 261c with Dave Harkrider. There were no books， just notes which the students dutifully transcribed from the blackboard. Don’s lectures were quite thorough and addressed the theory behind his cutting-edge science. During that first qua