Feb
26
Mon
Department Lecture Series
PAOC Colloquium (PAOCQ) – Noelle Selin (MIT) @ 54-915 and https://mit.zoom.us/j/94965503582
Feb 26 @ 12:00 pm – 1:00 pm
Feb
27
Tue

“Wiring the Subduction Megathrust: Recurring and Triggered Near-Trench Slow Slip Events and their Environment Along the Nankai Subduction Zone”

The offshore reaches of subduction megathrusts fail in a broad spectrum of slip modes, spanning from coseismic slip in great earthquakes, to tsunami earthquakes, to tremor and low frequency earthquakes, to slow slip events (SSEs) and aseismic creep. Understanding the nature of strain accumulation and release in this region is central to assessing hazards associated with shallow earthquake rupture and tsunamigenesis. In this talk I describe a family of recently discovered repeating SSE in the Nankai subduction zone offshore of Honshu Japan, up-dip of rupture zone of great (M8) earthquakes, using formation pore pressure data from instrumented borehole observatories. I then draw on a rapidly advancing body of drilling, laboratory, geophysical, and geodetic data from concerted efforts at several subduction zones over the last two decades, which have enabled an increasingly quantitative understanding of linked fluid- and frictional processes that underpin the spectrum of slip behavior, including: (1) pore pressure and stress states; (2) frictional stability, healing, and their dependence on lithology, stress, and slip velocity; and (3) permanent deformation of the upper plate and its role in the strain budget.

After filtering oceanographic noise using a local hydrostatic reference, the records reveal 13 SSEs in the Nankai Trough study area between 2010-2022. Of these, most arise spontaneously, and occur at ~1 yr intervals with durations of ~7-21 days. The remaining 2 events are larger and immediately follow: (1) the 2011 M9 Tohoku earthquake; and (2) the 2016 M7 Kumamoto earthquake. In some cases, the SSE are accompanied by swarms of low-frequency tremor and low-frequency earthquake activity that appear to migrate trenchward. The data are well fit by slip of ~1-4 cm on a patch at the plate interface that extends 20-40 km in the dip direction. The data are of sufficiently low noise that we are also able to evaluate the time evolution of slip by dividing each SSE into ~2 day sub-events. We develop simple slip models using Greens functions that incorporate the important effects of large gradients in elastic properties in the outer forearc. The results provide constraints on the location and magnitude of slip that best fits the pressure records, including the evolution of slip, its distribution, and its migration.

A key implication is that the SSEs accommodate ~30-50% of plate convergence across the outer ~40 km of the forearc. This coincides with a region of the shallow-most megathrust characterized by: (1) elevated pore fluid pressure; (2) transitional frictional behavior that promotes the nucleation of unstable slip at low sliding velocities – but containing patches that can fail more rapidly and radiate seismic energy; and (3) low total and differential stresses as constrained by analysis of wellbore failures and downhole drilling data. The repeating nature of the events, taken together with apparent triggering by regional earthquakes and the inference of low in situ stress magnitudes, indicates that the outermost reaches of the megathrust are highly sensitive to perturbation and are perched near a state of failure. In total, the data illuminate key controls on the spectrum of slip behavior, and are both mechanically and kinematically consistent with offshore geodetic observations of recurring shallow SSEs, tremor, and microseismicity; SSE slip distribution, slip rates, stress drops; and their correlation with elevated pore fluid pressure.

Department Lecture Series
Planetary Lunch Series (PLS) – Vincent Bourrier (University of Geneva) @ 54-517 and https://mit.zoom.us/j/93069069393
Feb 27 @ 12:30 pm – 1:30 pm

Title: TBD

Abstract: TBD

About this Series: The MIT Planetary Lunch Seminar [PLS] is a weekly seminar series organized within the EAPS department. Colloquia topics span the range of research interests of the department’s planetary sciences research program. The seminars take place on Tuesdays from 12:15–1:30 pm, unless otherwise noted (term-time only). Speakers include members of the MIT community and visitors. Talks are intended to appeal to graduate students, postdocs, research scientists, and faculty with a background in planetary science. For more information and Zoom password contact: planetary-org@mit.edu

Feb
29
Thu

Title: On Scientific Temptation, Transgression, and Fraud: Three Personal Stories

Abstract: I am going to tell you three very different stories from my career, with my own role and shortcomings in these conflicts unconcealed, and after each I am going to seek your views. What to do when you see fraud, assessing if it is intentional oraccidental, and trying to decide whether to contact the author, the journal or the author’s institution, are tough decisions. The personal risks of trying to expose or correct fraud are extremely high, particularly if you are a coauthor or a student, but often even if you are not. I will argue that fraud is slippery and gradational, not black and white. What’s essential is to be alert in our own work to the temptation to make the ambiguous unequivocal, and to remember that our job is to build and destroy our theses before the eyes of our readers.

Mar
1
Fri
Department Lecture Series
ERL FISH – Paul Woskoff (MIT) @ 54-209 and https://mit.zoom.us/j/95444505593
Mar 1 @ 12:00 pm – 1:00 pm

Title: Accessing Geothermal Energy with Millimeter-Wave Beams

Abstract: Earth has a huge heat content equal to 20 billon years of current global energy consumption. This energy could be accessed almost anywhere for efficient electricity generation by penetrating deep into the crust >16 km and establishing a high temperature gradient >50 Co/m for high-power, supercritical extraction at temperatures >373 Co.  Millimeter-wave (30 – 300 GHz) gyrotron sources, more powerful, efficient, and penetrating than infrared lasers, developed for fusion energy research have successfully ablated (>2,000 Co) laboratory holes in granite and basalt more easily than a mechanical drill.  The physics, economics, and technology are favorable for bringing the virtually limitless, clean energy of Earth to the surface.   About the speaker: Dr. Paul Woskov is a research engineer at the MIT Plasma Science and Fusion Center with degrees in Physics and Electrical Engineering. He has worked on major fusion energy experiments and spin off technologies to nuclear waste remediation, environmental monitoring, and geothermal energy.  Dr. Woskov is a member of APS, ANS, AAAS, life member of IEEE, and has won 6 R&D 100 Awards.

About the series: The MIT Earth Resources Laboratory’s Friday Informal Seminar Series (FISH) features talks by our lab members as well as special guests from academia and the energy industry on our areas of interest including geothermal energy, carbon sequestration, machine learning for geophysics, multiphase flow, subsurface imaging, and uncertainty quantification. Titles and abstracts will be posted here when available. For more info or Zoom password please contact erl-info@mit.edu.

Mar
4
Mon
Department Lecture Series
PAOC Colloquium (PAOCQ) – Steven Brown (NOAA Chemical Science Laboratory) @ 54-915 and https://mit.zoom.us/j/94965503582
Mar 4 @ 12:00 pm – 1:00 pm

Title: Ozone in Wildfire Smoke: Impact on Atmospheric Composition at Local, Regional and Global Scale

Mar
5
Tue
Department Lecture Series
EAPS Geophysics Seminar (12.571) – Christine Chesley (Woods Hole Oceanographic Institute) @ 54-209 and https://mit.zoom.us/j/99392380837
Mar 5 @ 10:00 am – 11:00 am

About the series: Seminar in Geophysics 12.571 is a class for MIT EAPS graduate students covering current topics in geophysics. Anyone from the MIT community is welcome to join for the talks by guest speakers which take place approximately every two weeks, usually on Tuesdays at 10am in 54-209 and on Zoom. Titles and abstracts will be posted here when available. Contact erl-info@mit.edu for Zoom password.

Department Lecture Series
Planetary Lunch Series (PLS) – Brynna Downey (UC Santa Cruz) @ 54-517 and https://mit.zoom.us/j/93069069393
Mar 5 @ 12:30 pm – 1:30 pm

Title: TBD

Abstract: TBD

About this Series: The MIT Planetary Lunch Seminar [PLS] is a weekly seminar series organized within the EAPS department. Colloquia topics span the range of research interests of the department’s planetary sciences research program. The seminars take place on Tuesdays from 12:15–1:30 pm, unless otherwise noted (term-time only). Speakers include members of the MIT community and visitors. Talks are intended to appeal to graduate students, postdocs, research scientists, and faculty with a background in planetary science. For more information and Zoom password contact: planetary-org@mit.edu

Mar
11
Mon
Department Lecture Series
PAOC Colloquium (PAOCQ) – Sandra Kirtland Turner (UC Riverside) @ 54-915 and https://mit.zoom.us/j/94965503582
Mar 11 @ 12:00 pm – 1:00 pm
Mar
18
Mon
Department Lecture Series
PAOC Colloquium (PAOCQ) – Becky Alexander (University of Washington) @ 54-915 and https://mit.zoom.us/j/94965503582
Mar 18 @ 12:00 pm – 1:00 pm