Remotely triggered nonvolcanic tremor in Sumbawa, Indonesia

Abstract

We present, for the first time, evidence for triggered tremor beneath the island of Sumbawa, Indonesia. We show triggered tremor in response to three teleseismic earthquakes: the M w 9.0 2011 Tohoku earthquake and two oceanic strike-slip earthquakes (M w 8.6 and M w 8.2) offshore of Sumatra in 2012. We constrain an apparent triggering threshold of 1 mm/s ground velocity that corresponds to about 8 kPa dynamic stress. Peak tremor amplitudes of about 180 nm/s are observed, and scale with the ground velocity induced by the remote earthquakes. Triggered tremor responds to 45-65 s period surface waves and predominantly correlates with Rayleigh waves, even though the 2012 oceanic events have stronger Love wave amplitudes. We could not locate the tremor because of minimal station coverage, but data indicate several potential source volumes including the Flores Thrust, the Java subduction zone, or Tambora volcano.

Delayed dynamic triggering: Local seismicity leading up to three remote M ≥ 6 aftershocks of the 11 April 2012 M8.6 Indian Ocean earthquake

“…The 16 M ≥ 5.5 triggered earthquakes reported by Pollitz et al [] all occur more than 14 h after the IOE, suggesting a failure process must exist that is more complex than Coulomb failure for these larger events [ Hill , ]. The IOE did immediately trigger remote tremor and low‐magnitude earthquakes ( M < 4) during the surface wave passage [ Aiken et al , , ; Chao and Obara , ; Fuchs et al , ; Gomberg and Prejean , ; Linville et al , ; Tape et al , ]. However, the data resolution in our study areas is not applicable to resolving triggered tremor.…”

Tectonic tremor along the northern Hikurangi Margin, New Zealand, between 2010 and 2015

“…Although many early tectonic tremor observations were associated with slow slip in the Nankai [ Obara , ] and Cascadia [ Rogers and Dragert , ] subduction zones, tremor associated with slow slip has more recently been identified in subduction zones such as Costa Rica [e.g., Brown et al ., ], Mexico [e.g., Payero et al ., ; Brudzinski et al ., ], Alaska [e.g., Peterson and Christensen , ], and New Zealand [ Kim et al ., ], as well as along transform boundaries such as the San Andreas Fault near Parkfield, California [e.g., Nadeau and Dolenc , ], and the Central Alpine Fault, New Zealand [e.g., Wech et al ., ]. In addition, tremor without geodetically detectable slow slip has been observed in other regions such as central Taiwan [e.g., Peng and Chao , ], southern Chile [ Gallego et al ., ], and Sumbawa, Indonesia [ Fuchs et al ., ], and is likely triggered by surface waves from teleseismic earthquakes. Tectonic tremor coincident with slow slip is nearly universally accepted to result from a multitude of low frequency earthquakes (LFE) overlapping in time such that individual body wave arrivals are rarely discernable.…”

High‐resolution deep tectonic tremor locations beneath the San Andreas Fault near Cholame, California, using the double‐pair double‐difference location method

“…Among them, tremor has been well studied since its first discovery in the subduction zone beneath southwest Japan [ Obara , ]. It is now observed along many plate‐boundary faults, including subduction zones in Cascadia [ Rogers and Dragert , ], New Zealand [ Kim et al , ], Mexico [ Payero et al , ], Alaska [ Peterson and Christensen , ], Costa Rica [ Walter et al , ] and Southern Chile [ Gallego et al , ], as well as strike‐slip faults and other inland faults in Central California [ Nadeau and Dolenc , ], Haida Gwaii [ Aiken et al ., ], Cuba [ Peng et al , ], Haiti [ Aiken et al , ], and Indonesia [ Fuchs et al , ; Bansal et al , ]. Tremor can either occur spontaneously, or be triggered by large teleseismic earthquakes [ Rubinstein et al , ; Gomberg et al , ; Peng and Chao , ; Peng et al , ; Chao et al , , ], regional earthquakes [ Guilhem et al , ], or tides [ Rubinstein et al , ; Nakata et al , ; Thomas et al , ].…”