Triggered tremor may simply be clock-advanced failure, which could make it useful

as a widely available ambient tremor and perhaps slow slip ‘meter’.

Volcano Island

Triggering depends on more than wave amplitude.

Posited Triggering Wave Amplitudes Vancouver Island (Cascadia)

Triggering depends on more than wave amplitude.

Posited Triggering Wave Amplitudes Vancouver Island (Cascadia)

Rubinstein et al. (2008)

Fault population with failures at a ~constant rate.

Clock-Advance Model

Perturbation advances (or delays) the failure times.

Clock-Advance Model

€

r(t) =r0(t)

(1−dΔt

dTf)perturbed rate

unperturbed rate

relationship between clock-advance & fault proximity to failure

[This underlies the ‘Dieterich (1994)’ aftershock model. Used in Beeler & Lockner (2003), Kaneko & Lapusta (2008), & others.]

Rate tests.

Cascadia Ambient Tremor Probabilities & Teleseism Origin Times

Sic

huan

P-W

aves Ambient Tremor

Triggered Tremor

2008 Wenchuan Earthquake Waves Arrive During ETS Event & Trigger Tremor

seconds

Per

u P

-Wav

es

Comparable 2007 Peru Earthquake Waves Arrive During Inter-ETS Time -> No Triggering

seconds

Denali Waves -> Instrumentation Matters!

PNSN

PN

SN

PN

SN

& C

NS

N

Amplitude tests: bigger perturbations -> bigger summed tremor.

Amplitude tests: bigger perturbations -> bigger summed tremor.

Suggestion of a scaling… data are noisy and scant.