Institute for Geophysics
University of Texas at Austin
Ph.D., Earth Sciences, University of California, Santa Cruz (2012)
B.A., Geology, University of Colorado at Boulder (2006)
Email: jwalter at ig.utexas.edu
Office: Bldg 196 Room 2.224
My research interests include ice sheet and glacier dynamics, tectonic tremor and slow slip, earthquakes, seismic triggering of earthquakes and other phenomena. I conduct research in Antarctica, Costa Rica, Greenland, and Alaska.
Geophysical Equipment: I maintain a pool of 14 broadband seismometers, active-source seismic gear, and other geophysical equipment for use in studies around the world.
Prospective Students: Please contact me if you are interested in becoming a graduate student.
Texas/Oklahoma seismicity (M > 2.5) in last 30 days (from USGS)
Induced seismicityIn Texas and other states throughout the US, earthquakes have been closely associated (in time and space) with oil and gas activities. Lately, we have been trying to identify when seismicity occurs and work with geologists and reservoir modelers to understand the conditions under which it occurs.
Slow slip and tremorI was previously involved in an NSF-funded project to study subduction zone processes at the Costa Rica Nicoya Peninsula. A combination of continuous GPS and seismic data allowed us to study ocean-continent plate collision at various timescales and spatial scales (See publications). Volcanoes are the result water-enriched sediments trapped in the downgoing slab. I am involved in trying to organize a seismotectonics project in the Western Solomon Islands.
SeismicityEarthquakes have the unique ability to trigger other earthquakes. This is a unique opportunity to understand what external stresses cause earthquakes and other phenomena, including icequakes and volcanic activity. Through careful geophysical studies we can get closer to predict the larger phenomena.
Frohlich, C. F., H. DeShon, B. Stump, C. Hayward, M. J. Hornbach, and J. I. Walter (2016), A historical review of induced earthquakes in Texas, Seismol. Res. Lett., 87(4), doi: 10.1785/0220160016. (link) (pdf)
Gimbert, F., V. C. Tsai, J. M. Amundson, T. C. Bartholomaus, and J. I. Walter (2016), Sub-seasonal changes in pressure, geometry, and sediment transport observed in subglacial channels, Geophys. Res. Lett., 43, 3786–3794, doi:10.1002/2016GL068337. (link) (pdf)
Walter, J. I., P. J. Dotray, C. Frohlich, and J. F. W. Gale (2016), Earthquakes in northwest Louisiana and the Texas-Louisiana border possibly induced by energy resource activities within the Haynesville shale play, Seismol. Res. Lett., 87(2A), doi:10.1785/0220150193. (link) (pdf)
Walter, J. I., Z. Peng, X. Meng, A. V. Newman, S. Y. Schwartz, and J. Marino Protti (2015), Far-field triggering of foreshocks near the nucleation zone of the 5 September 2012 (Mw 7.6) Nicoya Peninsula, Costa Rica earthquake, Earth and Planet. Sci. Lett., 431: 75-86, doi:10.1016/j.epsl.2015.09.017. (link) (pdf)
Bartholomaus, T. C., J. M. Amundson, J. I. Walter, S. O’Neel, M. E. West, and C. F. Larsen (2015), Subglacial discharge at tidewater glaciers revealed by seismic tremor, Geophys. Res. Lett., 42, doi:10.1002/2015GL064590. (Open Access link)
Malservisi, R., S. Y. Schwartz, N. Voss, M. Protti, V. Gonzalez, T. H. Dixon, Y. Jiang, A. V. Newman, J. Richardson, J. I. Walter, and D. Voyenko (2015), Multiscale postseismic behavior on a megathrust: The 2012 Nicoya earthquake, Costa Rica, Geochem. Geophys. Geosyst., 16, doi:10.1002/2015GC005794. (link)
Aiken, C., J. Zimmerman, Z. Peng, and J. I. Walter (2015), Triggered seismic events along the eastern Denali fault in northwest Canada following the 2012 Mw 7.8 Haida Gwaii, 2013 Mw 7.5 Craig, and two Mw>8.5 teleseismic earthquakes, Bull. of the Seismol. Soc. of Am., 105, no. 2B, doi: 10.1785/0120140156. (link)
Frohlich, C. F., J. I. Walter, and J. F. W. Gale (2015), Analysis of transportable array (USArray) data shows earthquakes are scarce near injection wells in the Williston Basin, 2008-2011, Seismol. Res. Lett., 86, 492-499. (link)
Walter, J. I., I. Svelitsky, J. Fineberg, S. Tulaczyk, E. E. Brodsky, C. G. Barcheck, and S. P. Carter (2015), Rupture speed dependence on initial stress profiles: Insights from glacier and laboratory stick-slip, Earth and Planet. Sci. Lett., 411: 112-120, http://dx.doi.org/10.1016/j.epsl.214.11.025. (Open Access link) (pdf)
Peng, Z., J. I. Walter, R. Aster, D. A. Wiens, S. Anandakrishnan, and A. Nyblade (2014), Antarctic icequakes triggered by the 2010 Maule earthquake in Chile, Nature Geosci., 7, 677–681, doi:10.1038/ngeo2212. (link)
Protti, M., V. Gonzalez, A. V. Newman, T. H. Dixon, S. Y. Schwartz, J. S. Marshall, L. Feng, J. I. Walter, R. Malservisi, and S. E. Owen (2014), Nicoya earthquake rupture anticipated by geodetic measurement of the locked plate interface, Nature Geosci., 7: 117-121, doi:10.1038/ngeo2038. (link)
Walter, J. I., S. Y. Schwartz, M. Protti, and V. Gonazalez (2013), The synchronous occurrence of shallow tremor and very low frequency earthquakes offshore of the Nicoya Peninsula, Costa Rica, Geophys. Res. Lett., 40, 1517-1522, doi:10.1002/grl.50213. (link (pdf)
Horgan, H. J., S. Anandakrishnan, R. W. Jacobel, K. Christianson, R. B. Alley, D. S. Heeszel, S. Picotti, and J. I. Walter (2012), Subglacial Lake Whillans - Part 1: Imaging a Shallow Active Reservoir Beneath a West Antarctic Ice Stream, Earth and Planet. Sci. Lett., 331: 201-209.
Walter, J. I., J. E. Box, S. Tulaczyk, E. E. Brodsky, I. M. Howat, Y. Ahn, and A. Brown (2012), Oceanic mechanical forcing of the dynamics of a marine-terminating Greenland glacier, Ann. Glaciol., 53(60 Pt 2) (link) (pdf)
Walter, J. I., E. E. Brodsky, S. Tulaczyk, S. Y. Schwartz, and R. Pettersson (2011), Transient slip events from near-field seismic and geodetic data on a glacier fault, Whillans Ice Plain, West Antarctica, J. Geophys. Res., 116, F01021, doi:10.1029/2010JF001754. (link) (pdf)
Walter, J. I., S. Y. Schwartz, J. M. Protti, and V. Gonzalez (2011), Persistent tremor within the northern Costa Rica seismogenic zone, Geophys. Res. Lett, 38, L01307, doi:10.1029/2010GL045586. (link) (pdf)
Outerbridge, K. C., T. H. Dixon, S. Y. Schwartz, J. I. Walter, M. Protti, V. Gonzalez, J. Biggs, M. Thorwart, and W. Rabbel (2010), A tremor and slip event on the Cocos-Caribbean subduction zone as measured by a GPS and seismic network on the Nicoya Peninsula, Costa Rica, J. Geophys. Res., 115, B10408, doi:10.1029/2009JB006845.
The influence of small stresses on the dynamics of glaciers and subduction zones (link)
This script pulls events that have been cataloged in Antelope, creates a whole directory of continuous waveforms in SAC format. Then, by reading the Antelope tables, it cuts continuous waveform data to make event-based waveforms. Here it is and be sure to change the variables in the script itself - getcontinuous_getevents_v1.sh. The script calls
both this tosac_from_msd_db2sac_v1.pl
and this sacarrivaltime_fromcont_v1.pl
Script to cut waveforms from continuous SAC files based on Antelope database phase/event picks - CutWaveforms_tomodd.bash
Script to calculate cross-correlation coefficient between different events between waveforms at the same station - cross_correlation_relocation_v2.bash
Combine the output from the cross_correlation_relocation_v2.bash script to output in a format recognizable by tomoDD - cc2dt_v2.pl