Relation of Slow Slip Events to Subsequent Earthquake Rupture
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Seismic Wave Triggering of Nonvolcanic Tremor, Episodic Tremor and Slip, and Earthquakes on Vancouver Island Justin L
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 114, B00A01, doi:10.1029/2008JB005875, 2009 Click Here for Full Article Seismic wave triggering of nonvolcanic tremor, episodic tremor and slip, and earthquakes on Vancouver Island Justin L. Rubinstein,1,2 Joan Gomberg,3 John E. Vidale,1 Aaron G. Wech,1 Honn Kao,4 Kenneth C. Creager,1 and Garry Rogers4 Received 16 June 2008; revised 14 October 2008; accepted 20 November 2008; published 19 February 2009. [1] We explore the physical conditions that enable triggering of nonvolcanic tremor and earthquakes by considering local seismic activity on Vancouver Island, British Columbia during and immediately after the arrival of large-amplitude seismic waves from 30 teleseismic and 17 regional or local earthquakes. We identify tremor triggered by four of the teleseismic earthquakes. The close temporal and spatial proximity of triggered tremor to ambient tremor and aseismic slip indicates that when a fault is close to or undergoing failure, it is particularly susceptible to triggering of further events. The amplitude of the triggering waves also influences the likelihood of triggering both tremor and earthquakes such that large amplitude waves triggered tremor in the absence of detectable aseismic slip or ambient tremor. Tremor and energy radiated from regional/local earthquakes share the same frequency passband so that tremor cannot be identified during these smaller, more frequent events. We confidently identify triggered local earthquakes following only one teleseism, that with the largest amplitude, and four regional or local events that generated vigorous aftershock sequences in their immediate vicinity. Earthquakes tend to be triggered in regions different from tremor and with high ambient seismicity rates. -
The Moment Magnitude and the Energy Magnitude: Common Roots
The moment magnitude and the energy magnitude : common roots and differences Peter Bormann, Domenico Giacomo To cite this version: Peter Bormann, Domenico Giacomo. The moment magnitude and the energy magnitude : com- mon roots and differences. Journal of Seismology, Springer Verlag, 2010, 15 (2), pp.411-427. 10.1007/s10950-010-9219-2. hal-00646919 HAL Id: hal-00646919 https://hal.archives-ouvertes.fr/hal-00646919 Submitted on 1 Dec 2011 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Click here to download Manuscript: JOSE_MS_Mw-Me_final_Nov2010.doc Click here to view linked References The moment magnitude Mw and the energy magnitude Me: common roots 1 and differences 2 3 by 4 Peter Bormann and Domenico Di Giacomo* 5 GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany 6 *Now at the International Seismological Centre, Pipers Lane, RG19 4NS Thatcham, UK 7 8 9 Abstract 10 11 Starting from the classical empirical magnitude-energy relationships, in this article the 12 derivation of the modern scales for moment magnitude M and energy magnitude M is 13 w e 14 outlined and critically discussed. The formulas for Mw and Me calculation are presented in a 15 way that reveals, besides the contributions of the physically defined measurement parameters 16 seismic moment M0 and radiated seismic energy ES, the role of the constants in the classical 17 Gutenberg-Richter magnitude-energy relationship. -
Sparsity-Based Estimates of Slow Slip Distributions in Cascadia
United States Geological Survey Earthquake Hazards Program Final Technical Report USGS Award Number G17AP00026 Sparsity-based estimates of slow slip distributions in Cascadia Author: John Loveless Department of Geosciences Smith College Clark Science Center 44 College Lane Northampton, MA 01063, USA Phone: (413) 585-2657 Fax: (413) 585-3786 Email: [email protected] Other personnel: Elias Molitors Bergman, Smith College Post-baccalaureate Research Assistant Sofia Johnson, Smith College Summer Undergraduate Research Fellow Eileen Evans, United States Geological Survey Collaborator Award Term: January 1, 2017–December 31, 2017 ABSTRACT Since the first geodetic detection of slow slip events (SSEs) on the Cascadia Subduction Zone in the 1990s, the role that these events play in the seismic moment balance of the plate boundary zone has been intensely studied. Slip during the events has been estimated to take place below the portion of the subduction zone that is inferred to be interseismically coupled and therefore most likely to generate future large earthquakes. However, the degree of spatial separation between the coupled and/or seismogenic zone, and the slowly slipping zone is ambiguous, in part because of the smoothing-based regularization technique that has been employed in many inversions of geodetic displacement fields for slow slip distributions. In this funded research, we compare two regularization strategies in estimating the distribution of slow slip: the classic smoothing-based approach and total variation regularization (TVR), which seeks spatial clusters of homogeneous slip, the magnitude of which may vary abruptly from patch to patch. Whereas smoothing inherently blurs the spatial distribution of estimated slow slip, and hence the degree to which that distribution may overlap with patterns of coupling and/or coseismic slip, TVR enables imaging of spatially distinct regions of slip behaviors. -
Fully-Coupled Simulations of Megathrust Earthquakes and Tsunamis in the Japan Trench, Nankai Trough, and Cascadia Subduction Zone
Noname manuscript No. (will be inserted by the editor) Fully-coupled simulations of megathrust earthquakes and tsunamis in the Japan Trench, Nankai Trough, and Cascadia Subduction Zone Gabriel C. Lotto · Tamara N. Jeppson · Eric M. Dunham Abstract Subduction zone earthquakes can pro- strate that horizontal seafloor displacement is a duce significant seafloor deformation and devas- major contributor to tsunami generation in all sub- tating tsunamis. Real subduction zones display re- duction zones studied. We document how the non- markable diversity in fault geometry and struc- hydrostatic response of the ocean at short wave- ture, and accordingly exhibit a variety of styles lengths smooths the initial tsunami source relative of earthquake rupture and tsunamigenic behavior. to commonly used approach for setting tsunami We perform fully-coupled earthquake and tsunami initial conditions. Finally, we determine self-consistent simulations for three subduction zones: the Japan tsunami initial conditions by isolating tsunami waves Trench, the Nankai Trough, and the Cascadia Sub- from seismic and acoustic waves at a final sim- duction Zone. We use data from seismic surveys, ulation time and backpropagating them to their drilling expeditions, and laboratory experiments initial state using an adjoint method. We find no to construct detailed 2D models of the subduc- evidence to support claims that horizontal momen- tion zones with realistic geometry, structure, fric- tum transfer from the solid Earth to the ocean is tion, and prestress. Greater prestress and rate-and- important in tsunami generation. state friction parameters that are more velocity- weakening generally lead to enhanced slip, seafloor Keywords tsunami; megathrust earthquake; deformation, and tsunami amplitude. -
Rapid Identification of Tsunamigenic Earthquakes Using GNSS
www.nature.com/scientificreports OPEN Rapid identifcation of tsunamigenic earthquakes using GNSS ionospheric sounding Fabio Manta1,2,4*, Giovanni Occhipinti 3,4, Lujia Feng 1 & Emma M. Hill 1,2 The largest tsunamis are generated by seafoor uplift resulting from rupture of ofshore subduction- zone megathrusts. The rupture of the shallowest part of a megathrust often produces unexpected outsize tsunami relative to their seismic magnitude. These are so called ‘tsunami earthquakes’, which are difcult to identify rapidly using the current tsunami warning systems, even though, they produce some of the deadliest tsunami. We here introduce a new method to evaluate the tsunami risk by measuring ionospheric total electron content (TEC). We examine two Mw 7.8 earthquakes (one is a tsunami earthquake and the other is not) generated in 2010 by the Sunda megathrust, ofshore Sumatra, to demonstrate for the frst time that observations of ionospheric sounding from Global Navigation Satellite System (GNSS) can be used to evaluate the tsunamigenic potential of earthquakes as early as 8 min after the mainshock. ‘Tsunami earthquakes’, as originally defned by Kanamori 1, are events generating tsunami with larger amplitude than expected from their seismic magnitude. Most tsunami earthquakes are generated by high levels of slip on the shallow megathrust, which results in large seafoor uplifs and hence very dangerous tsunami. Te shallow location of the slip—close to the subduction trench—means that the ruptures generating tsunami earthquakes are at signifcant distance from land-based monitoring networks, limiting our ability to quickly and accurately assess their magnitude and source parameters. Conventional approaches using various seismological methods2–4 or rapid inversion of GNSS (Global Navigation Satellite System) estimates of ground motion5 regularly encounter difculties in accurately estimating the uplif of the seafoor and consequently fail in predicting the tsunamigenic nature of tsunami earthquakes. -
Episodic Tremor and Slip in the Pacific Northwest
winter/spring 2007 featured science: Episodic Tremor and Slip in the Pacific Northwest Every 14 months the Pacific Northwest experiences slow slip on a aultf that is the equivalent of about a magnitude 6.5 earthquake. While a typical earthquake of this magnitude happens in less than 10 seconds, the duration of these slip events is two to several weeks. The most recent event occurred from January 14 through February 1, 2007. In the Pacific Northwest, the Juan de onSitenewsletter Fuca plate is subducting (or dipping) beneath the North American plate from northern California From The Principal Investigators to Vancouver Island. EarthScope’s multi-disciplinary approach These plates slide past to improving our understanding of the structure each other along the and formation of continents and the physical solid green, dashed Figure 1. Courtesy of H. Dragert, Geological Survey of Canada processes that control earthquakes and yellow and dashed red lines in Figure 1. The Cascadia subduction zone, as it is volcanoes has spurred the development of new called, experiences large earthquakes, perhaps as large as the 2004 Sumatra techniques for analyzing and interpreting many earthquake, once every 500 years on average. The last one was about 300 years types of geophysical data. Throughout this issue, ago in January 1700. The slip during these earthquakes, occurring on the “locked” we highlight some of EarthScope’s integrated zone in the figure, is thought to accommodate most, if not all, of the relative activities. motion between the North American plate and the Juan de Fuca plate. Down dip of this locked zone (red dashed lines), the plates must still slide past each In our science feature, two EarthScope researchers, Ken Creager of the University of other. -
Cascadia Low Frequency Earthquakes at the Base of an Overpressured Subduction Shear Zone ✉ Andrew J
ARTICLE https://doi.org/10.1038/s41467-020-17609-3 OPEN Cascadia low frequency earthquakes at the base of an overpressured subduction shear zone ✉ Andrew J. Calvert 1 , Michael G. Bostock 2, Geneviève Savard 3 & Martyn J. Unsworth4 In subduction zones, landward dipping regions of low shear wave velocity and elevated Poisson’s ratio, which can extend to at least 120 km depth, are interpreted to be all or part of the subducting igneous oceanic crust. This crust is considered to be overpressured, because fl 1234567890():,; uids within it are trapped beneath an impermeable seal along the overlying inter-plate boundary. Here we show that during slow slip on the plate boundary beneath southern Vancouver Island, low frequency earthquakes occur immediately below both the landward dipping region of high Poisson’s ratio and a 6–10 km thick shear zone revealed by seismic reflections. The plate boundary here either corresponds to the low frequency earthquakes or to the anomalous elastic properties in the lower 3–5 km of the shear zone immediately above them. This zone of high Poisson’s ratio, which approximately coincides with an electrically conductive layer, can be explained by slab-derived fluids trapped at near-lithostatic pore pressures. 1 Department of Earth Sciences, Simon Fraser University, 8888 University Drive, Burnaby, BC V5A 1S6, Canada. 2 Department of Earth, Ocean and Atmospheric Sciences, 2207 Main Mall, University of British Columbia, Vancouver, BC V6T 1Z4, Canada. 3 Department of Geosciences, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada. 4 Department of Physics, University of Alberta, Edmonton, AB T6G 2E9, Canada. -
A Test for the Mediterranean Tsunami Warning System Mohammad Heidarzadeh1* , Ocal Necmioglu2 , Takeo Ishibe3 and Ahmet C
Heidarzadeh et al. Geosci. Lett. (2017) 4:31 https://doi.org/10.1186/s40562-017-0097-0 RESEARCH LETTER Open Access Bodrum–Kos (Turkey–Greece) Mw 6.6 earthquake and tsunami of 20 July 2017: a test for the Mediterranean tsunami warning system Mohammad Heidarzadeh1* , Ocal Necmioglu2 , Takeo Ishibe3 and Ahmet C. Yalciner4 Abstract Various Tsunami Service Providers (TSPs) within the Mediterranean Basin supply tsunami warnings including CAT-INGV (Italy), KOERI-RETMC (Turkey), and NOA/HL-NTWC (Greece). The 20 July 2017 Bodrum–Kos (Turkey–Greece) earth- quake (Mw 6.6) and tsunami provided an opportunity to assess the response from these TSPs. Although the Bodrum– Kos tsunami was moderate (e.g., runup of 1.9 m) with little damage to properties, it was the frst noticeable tsunami in the Mediterranean Basin since the 21 May 2003 western Mediterranean tsunami. Tsunami waveform analysis revealed that the trough-to-crest height was 34.1 cm at the near-feld tide gauge station of Bodrum (Turkey). Tsunami period band was 2–30 min with peak periods at 7–13 min. We proposed a source fault model for this tsunami with the length and width of 25 and 15 km and uniform slip of 0.4 m. Tsunami simulations using both nodal planes produced almost same results in terms of agreement between tsunami observations and simulations. Diferent TSPs provided tsunami warnings at 10 min (CAT-INGV), 19 min (KOERI-RETMC), and 18 min (NOA/HL-NTWC) after the earthquake origin time. Apart from CAT-INGV, whose initial Mw estimation difered 0.2 units with respect to the fnal value, the response from the other two TSPs came relatively late compared to the desired warning time of ~ 10 min, given the difculties for timely and accurate calculation of earthquake magnitude and tsunami impact assessment. -
Model for Triggering of Non-Volcanic Tremor by Earthquakes
Wright State University CORE Scholar Physics Faculty Publications Physics 2012 Model for Triggering of Non-Volcanic Tremor by Earthquakes Naum I. Gershenzon Wright State University - Main Campus, [email protected] Gust Bambakidis Wright State University - Main Campus, [email protected] Follow this and additional works at: https://corescholar.libraries.wright.edu/physics Part of the Physics Commons Repository Citation Gershenzon, N. I., & Bambakidis, G. (2012). Model for Triggering of Non-Volcanic Tremor by Earthquakes. https://corescholar.libraries.wright.edu/physics/552 This Article is brought to you for free and open access by the Physics at CORE Scholar. It has been accepted for inclusion in Physics Faculty Publications by an authorized administrator of CORE Scholar. For more information, please contact [email protected]. Model for triggering of non-volcanic tremor by earthquakes Naum I. Gershenzon1,2, Gust Bambakidis1 1Physics Department, Wright State University, 3640 Colonel Glenn Highway Dayton, OH 45435 2Department of Earth and Environmental Sciences, Wright State University, 3640 Colonel Glenn Highway Dayton, OH 45435 [1] There is evidence of tremor triggering by seismic waves emanating from distant large earthquakes. The frequency content of both triggered and ambient tremor are largely identical, suggesting that this property does not depend directly on the nature of the source. We show here that the model of plate dynamics developed earlier by us is an appropriate tool for describing tremor triggering. In the framework of this model, tremor is an internal response of a fault to a failure triggered by external disturbances. The model predicts generation of radiation in a frequency range defined by the fault parameters. -
Caribbean Tsunami Hazard
ESTIMATING THE THREAT OF TSUNAMIGENIC EARTHQUAKES AND EARTHQUAKE INDUCED-LANDSLIDE TSUNAMI IN THE CARIBBEAN WILLIAM R. MCCANN Earth Scientific Consultants Westminster, CO 80021, USA Deformation along the margin of the Caribbean Plate is the principal cause of the tsunami threat in the Caribbean. That margin parallels the northern coast of South America, the Lesser Antilles, and extends along the Greater Antilles from Puerto Rico through Jamaica. The eastern boundary of the Caribbean plate near the Lesser Antilles is the locus of subduction of Atlantic seafloor. At least three distinct, shallow tectonic regimes parallel the margin. They are: an outer tectonic belt where the North America Plate bends to enter the subduction zone, the main interface or zone of contact between the plates, and an inner zone of intraplate activity in the overriding Caribbean Plate. The level of seismic activity and tsunami potential in each of these zones is influenced by the presence of aseismic ridges on the downgoing plate. Ridges may increase the probability of tsunami or slow earthquakes, by reactivating thrust faults in the accretionary prism. The northeastern corner of the Caribbean Plate margin has a smooth transition from the relatively simple subduction zone in the Northern Lesser Antilles into a region of oblique convergence. It is a complex margin dominated by microplate tectonics from near Puerto Rico through Hispaniola. Here too the same three tectonic zones can be defined, but the third zone, “intraplate activity in the Caribbean Plate”, is more clearly delineated as microplate deformation in a wide plate boundary zone. Strike-slip tectonics dominates the region from Haiti westward to the northern coast of Honduras. -
The 25 October 2010 Sumatra Tsunami Earthquake: Slip in a Slow Patch Susan L
GEOPHYSICAL RESEARCH LETTERS, VOL. 38, L14306, doi:10.1029/2011GL047864, 2011 The 25 October 2010 Sumatra tsunami earthquake: Slip in a slow patch Susan L. Bilek,1 E. Robert Engdahl,2 Heather R. DeShon,3 and Maya El Hariri1 Received 20 April 2011; revised 13 June 2011; accepted 15 June 2011; published 28 July 2011. [1] Various models for the generation of tsunami earthquakes and shallow afterslip [e.g., Hsu et al., 2006; earthquakes have been proposed, including shallow Konca et al., 2008] (Figure 1). Approximately 700 km north, earthquake slip through low strength materials. Because another tsunami earthquake may have occurred along these physical fault conditions would likely affect other Simeulue Island in 1907 [Kanamori et al., 2010]. earthquakes in the same rupture zone, source properties of [3] Given that models link shallow slip in weak near‐trench other events may provide a guide to locations of tsunami materials to tsunami earthquake occurrence, an important earthquakes. The 25 October 2010 Mw = 7.8 Mentawai question is whether these fault conditions also impact the tsunami earthquake and surrounding events provide a test rupture of other events in the same area. Our efforts here of this hypothesis. We determine slip patterns for the address this question by first defining the rupture area and mainshock and relocate aftershocks, with the majority source characteristics of the 2010 event as well as relocating occurring in the near trench region. The two largest aftershocks of the event. We then compare the rupture extent magnitude aftershocks occurred within the downdip end of to source parameters computed for other regional earthquakes the mainshock rupture area and have long moment‐ in order to assess the possibility of consistent slow behavior normalized rupture duration, likely related to fault zone along specific patches of the plate interface. -
Geodetic and Seismic Signatures of Episodic Tremor and Slip in the Northern Cascadia Subduction Zone
Earth Planets Space, 56, 1143–1150, 2004 Geodetic and seismic signatures of episodic tremor and slip in the northern Cascadia subduction zone H. Dragert, K. Wang, and G. Rogers Geological Survey of Canada, Pacific Geoscience Centre, Sidney, B.C., V8L 4B2, Canada (Received June 2, 2004; Revised December 2, 2004; Accepted December 24, 2004) Slip events with an average duration of about 10 days and effective total slip displacements of severalc entimetres have been detected on the deeper (25 to 45 km) part of the northern Cascadia subduction zone interface by observing transient surface deformation on a network of continuously recording Global Positioning System (GPS) sites. The slip events occur down-dip from the currently locked, seismogenic portion of the subduction zone, and, for the geographic region around Victoria, British Columbia, repeat at 13 to 16 month intervals. These episodes of slip are accompanied by distinct, low-frequency tremors, similar to those reported in the forearc region of southern Japan. Although the processes which generate this phenomenon of episodic tremor and slip (ETS) are not well understood, it is possible that the ETS zone may constrain the landward extent of megathrust rupture, and conceivable that an ETS event could precede the next great thrust earthquake. Key words: Crustal deformation, GPS, slow earthquakes, non-volcanic tremors, Cascadia margin. 1. Introduction of continuous GPS sites in northern Cascadia are marked by Beginning in 1992, increasing numbers of automated numerous, brief, episodic reversals. This is best illustrated continuous Global Positioning System (GPS) sites have by the east-component time series at the Victoria GPS site been established in southwestern British Columbia and (ALBH) where the motion relative to DRAO is clearly char- northwestern United States in order to monitor crustal mo- acterized by a sloped saw-tooth function: For periods of 13 tions due to present-day tectonics.