Locally generated tsunamis recorded on the coast of British Columbia

Rabinovich, Alexander B.; Thomson, Richard E.; Titov, Vasily V.; Stephenson, F.; Rogers, Garry C.

doi:10.3137/ao.460304

Cited by 17 publications

(10 citation statements)

References 30 publications

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“…The Craig earthquake is similar in mechanism and magnitude to many of the historic strike-slip events along the QCF. The Haida Gwaii event was exceptional because it was significantly larger in moment magnitude than other thrust events along the transpressional southern QCF system (Ristau et al, 2007;Rabinovich et al, 2008). It was followed by normal-faulting aftershocks within the Pacific plate, likely generated from bending of the Pacific plate in response to underthrusting (Lay et al, 2013;Kao et al, 2015).…”

Section: Introductionmentioning

confidence: 98%

Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures

Walton

Gulick

Haeussler

et al. 2015

Bulletin of the Seismological Society of America

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The Queen Charlotte fault (QCF) is a dextral transform system located offshore of southeastern Alaska and western Canada, accommodating ∼4:4 cm=yr of relative motion between the Pacific and North American plates. Oblique convergence along the fault increases southward, and how this convergence is accommodated is still debated. Using seismic reflection data, we interpret offshore basement structure, faulting, and stratigraphy to provide a geological context for two recent earthquakes, an M w 7.5 strike-slip event near Craig, Alaska, and an M w 7.8 thrust event near Haida Gwaii, Canada. We map downwarped Pacific oceanic crust near 54°N, between the two rupture zones. Observed downwarping decreases north and south of 54°N, parallel to the strike of the QCF. Bending of the Pacific plate here may have initiated with increased convergence rates due to a plate motion change at ∼6 Ma. Tectonic reconstruction implies convergence-driven Pacific plate flexure, beginning at 6 Ma south of a 10°bend the QCF (which is currently at 53.2°N) and lasting until the plate translated past the bend by ∼2 Ma. Normal-faulted approximately late Miocene sediment above the deep flexural depression at 54°N, topped by relatively undeformed Pleistocene and younger sediment, supports this model. Aftershocks of the Haida Gwaii event indicate a normal-faulting stress regime, suggesting present-day plate flexure and underthrusting, which is also consistent with reconstruction of past conditions. We thus favor a Pacific plate underthrusting model to initiate flexure and accommodation space for sediment loading. In addition, mapped structures indicate two possible fault segment boundaries along the QCF at 53.2°N and at 56°N.

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Section: Introductionmentioning

confidence: 98%

Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures

Walton

Gulick

Haeussler

et al. 2015

Bulletin of the Seismological Society of America

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“…Despite its relatively low magnitude, this underwater earthquake generated a tsunami which was clearly recorded by four tide gauges on the coast of Vancouver IslandBamfield, Tofino, Winter Harbour, and Port Hardy (RABINOVICH and STEPHENSON, 2004;RABINOVICH et al, 2008b). Maximum wave heights for the four gauge sites were quite consistent, ranging from a minimum of 11.3 cm at Bamfield to a maximum of 22.7 cm at Winter Harbour (Fig.…”

Section: -2007: Distant Eventsmentioning

confidence: 81%

“…Space precludes including some of this material in the paper, however, examples are available in other publications (e.g., RABINOVICH et al, 2006aRABINOVICH et al, , 2006bRABINOVICH et al, , 2008b.…”

Section: Discussionmentioning

confidence: 99%

“…Over 700 earthquakes were detected. While swarm activity is not uncommon in the tectonically active, thin oceanic lithosphere west of Vancouver Island, this swarm was unusual because it did not occur along any of the previously recognized offshore fault zones (RABINOVICH et al, 2008b). The largest event (M w = 6.6) was on November 2 at 10:02 UTC at an effective depth of 9 km.…”

Section: -2007: Distant Eventsmentioning

confidence: 98%

“…The major topographic admittance peaks at most of the stations were determined to be located at periods less than 12 min (cf., RABINOVICH and STEPHENSON, 2004;FINE et al, 2008). Also some of the recent tsunami events (2001 Queen Charlotte;2004 Vancouver Island;2005 California;2007 Kuril Islands) had major source energy at relatively high frequencies (cf., RABINOVICH and STEPHENSON, 2004;RABINOVICH et al, 2006bRABINOVICH et al, , 2008b. Thus, reducing the sample interval to 6 minutes would deprive us of some important information about long waves in the tsunami frequency band and may create serious aliasing problems (cf., EMERY and THOMSON, 2003).…”

Section: Observational Problemsmentioning

confidence: 99%

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Tsunamis on the Pacific Coast of Canada Recorded in 1994–2007

Stephenson

Rabinovich

2009

Pure appl. geophys.

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In the last 15 years there have been 16 tsunami events recorded at tide stations on the Pacific Coast of Canada. Eleven of these events were from distant sources covering almost all regions of the Pacific, as well as the December 26, 2004 Sumatra tsunami in the Indian Ocean. Three tsunamis were generated by local or regional earthquakes and two were meteorological tsunamis. The earliest four events, which occurred in the period 1994-1996, were recorded on analogue recorders; these tsunami records were recently re-examined, digitized and thoroughly analysed. The other 12 tsunami events were recorded using digital high-quality instruments, with 1-min sampling interval, installed on the coast of British Columbia (B.C.) in 1998. All 16 tsunami events were recorded at Tofino on the outer B.C. coast, and some of the tsunamis were recorded at eight or more stations. The tide station at Tofino has been in operation for 100 years and these recent observations add to the dataset of tsunami events compiled previously by S.O. WIGEN (1983) for the period 1906-1980. For each of the tsunami records statistical analysis was carried out to determine essential tsunami characteristics for all events (arrival times, maximum amplitudes, frequencies and wave-train structure). The analysis of the records indicated that significant background noise at Langara, a key northern B.C. Tsunami Warning station located near the northern end of the Queen Charlotte Islands, creates serious problems in detecting tsunami waves. That station has now been moved to a new location with better tsunami response. The number of tsunami events observed in the past 15 years also justified re-establishing a tide gauge at Port Alberni, where large tsunami wave amplitudes were measured in March 1964. The two meteorological events are the first ever recorded on the B.C. coast. Also, there have been landslide generated tsunami events which, although not recorded on any coastal tide gauges, demonstrate, along with the recent investigation of a historical catastrophic event, the significant risk that landslide generated tsunami pose to coastal and inland regions of B.C.

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A tsunami generated by a strike-slip event: constraints from GPS and SAR data on the 2018 Palu earthquake

Simons

Broerse

Shen

et al. 2022

Preprint

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A devastating tsunami struck Palu Bay in the wake of the 28 September 2018 M w = 7.5 Palu earthquake (Sulawesi, Indonesia). With a predominantly strike-slip mechanism, the question remains whether this unexpected tsunami was generated by the earthquake itself, or rather by earthquake-induced landslides. In this study we examine the tsunami potential of the co-seismic deformation. To this end, we present a novel geodetic data set of Global Positioning System and multiple Synthetic Aperture Radar-derived displacement fields to estimate a 3D co-seismic surface deformation field. The data reveal a number of fault bends, conforming to our interpretation of the tectonic setting as a transtensional basin. Using a Bayesian framework, we provide robust finite fault solutions of the co-seismic slip distribution, incorporating several scenarios of tectonically feasible fault orientations below the bay. These finite fault scenarios involve large co-seismic uplift (>2 m) below the bay due to thrusting on a restraining fault bend that connects the offshore continuation of two parallel onshore fault segments. With the co-seismic displacement estimates as input we simulate a number of tsunami cases. For most locations for which video-derived tsunami waveforms are available our models provide a qualitative fit to leading wave arrival times and polarity. The modeled tsunamis explain most of the observed runup. We conclude that co-seismic deformation was the main driver behind the tsunami that followed the Palu earthquake. Our unique geodetic data set constrains vertical motions of the sea floor, and sheds new light on the tsunamigenesis of strike-slip faults in transtensional basins.

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Locally generated tsunamis recorded on the coast of British Columbia

Abstract: This study presents analyses and numerical simulations of local tsunamis generated by two recent earthquakes off the coast of British 11.3, 18.2, 22.7 and 14.5 cm, respectively de 11,3, 18,2, 22,7 et 14,5 cm, respectivement

Cited by 17 publications

References 30 publications

Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures

Basement and Regional Structure Along Strike of the Queen Charlotte Fault in the Context of Modern and Historical Earthquake Ruptures

Tsunamis on the Pacific Coast of Canada Recorded in 1994–2007

A tsunami generated by a strike-slip event: constraints from GPS and SAR data on the 2018 Palu earthquake

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