Breaking Cascadia's Silence: Machine Learning Reveals the Constant Chatter of the Megathrust

Tectonic faults slip in various manners, ranging from ordinary earthquakes to slow slip events to aseismic fault creep. The frequent occurrence of slow earthquakes and their sensitivity to stress make them a promising probe of the neighboring locked zone where megaquakes take place. This relationship, however, remains poorly understood. We show that the Cascadia megathrust is continuously broadcasting a tremor-like signal that precisely informs of fault displacement rate throughout the slow slip cycle. We posit that this signal provides indirect, real-time access to physical properties of the megathrust and may ultimately reveal a connection between slow slip and megaquakes.

[1]  C. Humphreys,et al.  Machine Learning Predicts Laboratory Earthquakes , 2017, Geophysical Research Letters.

[2]  W. Frank.  Slow slip hidden in the noise: The intermittence of tectonic release , 2016 .

[3]  H. Dragert,et al.  Episodic Tremor and Slip on the Cascadia Subduction Zone: The Chatter of Silent Slip , 2003, Science.

[4]  Aaron G. Wech,et al.  Automated detection and location of Cascadia tremor , 2008 .

[5]  Timothy Ian Melbourne,et al.  Seismic and geodetic constraints on Cascadia slow slip , 2008 .

[6]  Kazushige Obara,et al.  Nonvolcanic Deep Tremor Associated with Subduction in Southwest Japan , 2002, Science.

[7]  H. Kao,et al.  Northern Cascadia episodic tremor and slip: A decade of tremor observations from 1997 to 2007 , 2009 .

[8]  A. Kato,et al.  Connecting slow earthquakes to huge earthquakes , 2016, Science.

[9]  Kelin Wang,et al.  Spatial‐temporal patterns of seismic tremors in northern Cascadia , 2006 .

[10]  C. Goldfinger,et al.  HOLOCENE EARTHQUAKE RECORDS FROM THE CASCADIA SUBDUCTION ZONE AND NORTHERN SAN ANDREAS FAULT BASED ON PRECISE DATING OF OFFSHORE TURBIDITES , 2003 .

[11]  Anthony Sladen,et al.  Seismic and aseismic slip on the Central Peru megathrust , 2010, Nature.

[12]  A. C. Aguiar,et al.  Moment release rate of Cascadia tremor constrained by GPS , 2009 .

[13]  C. Lasserre,et al.  Revealing the cluster of slow transients behind a large slow slip event , 2017, Science Advances.

[14]  A. Gualandi,et al.  Triggering of the 2014 Mw7.3 Papanoa earthquake by a slow slip event in Guerrero, Mexico , 2016 .

[15]  W. Brace,et al.  Stick-Slip as a Mechanism for Earthquakes , 1966, Science.

[16]  A. Rubin,et al.  Short‐time scale correlation between slow slip and tremor in Cascadia , 2011 .

[17]  R. Clayton,et al.  The 2006 slow slip event and nonvolcanic tremor in the Mexican subduction zone , 2010 .

[18]  Paul A. Johnson,et al.  Estimating Fault Friction From Seismic Signals in the Laboratory , 2017, 1710.04172.

[19]  R. Madariaga,et al.  Intense foreshocks and a slow slip event preceded the 2014 Iquique Mw 8.1 earthquake , 2014, Science.

[20]  Naoshi Hirata,et al.  Propagation of Slow Slip Leading Up to the 2011 Mw 9.0 Tohoku-Oki Earthquake , 2012, Science.

[21]  Kenji Satake,et al.  Time and size of a giant earthquake in Cascadia inferred from Japanese tsunami records of January 1700 , 1996, Nature.

[22]  J. Murray,et al.  Global Positioning System Data Collection, Processing, and Analysis Conducted by the U.S. Geological Survey Earthquake Hazards Program , 2017 .

[23]  A. Wech,et al.  Slip rate and tremor genesis in Cascadia , 2014 .

[24]  Leon Bieber.  The Mechanics Of Earthquakes And Faulting , 2016 .

[25]  Andrew M. Bradley,et al.  Space‐time correlation of slip and tremor during the 2009 Cascadia slow slip event , 2011 .

[26]  M. Kido,et al.  Episodic slow slip events in the Japan subduction zone before the 2011 Tohoku-Oki earthquake , 2012 .

[27]  B. Rouet-Leduc,et al.  Estimating the Physical State of a Laboratory Slow Slipping Fault from Seismic Signals , 2018, 1801.07806.

[28]  A. Hasegawa,et al.  Preceding seismic activity and slow slip events in the source area of the 2011 Mw 9.0 Tohoku-Oki earthquake: a review , 2015, Geoscience Letters.