Large earthquakes are often preceded or followed by slow-slip events, which when better understood may help better understand the mechanisms of the earthquakes and the possibility of their prediction. This chapter summarizes kinematic values of large slow-slip events observed in Circum-Pacific subduction zones and creep events observed along strike-slip faults in California. The kinematic parameters include maximum slip S, duration T, rupture length L, rupture width, magnitude M, slip velocity VS, rupture velocity VR, and maximum slip/rupture length ratio S/L. For a large surface and subsurface creep event in California: S = 0.9–2.5 cm, T = 2–5 day, L = 6–8 km, W = 3–4 km, M = 4.7–4.8, VS = 0.4–0.5 cm/d, VR = 1.6–3.0 km/d, and S/L = 0.3–1.5 × 10−6. For a large short-term slow-slip event in Circum-Pacific subduction zones: S = 1–20 cm, T = 2–50 day, L = 20–260 km, W = 10–90 km, M = 5.6–7.0, VS = 0.1–0.8 cm/d, VR = 2–20 km/d, and S/L = 0.3–1.5 × 10−6. The latter kind of events have larger sizes in slip, duration, rupture length/width, and magnitude than the former, but are comparable in slip velocity, rupture velocity, and S/L ratio. The kinematic behaviors of both are similar, despite their large difference in temperature, pressure, and composition of the fault-zone materials. The larger size of the latter is probably due to their larger inertia caused by their larger overburden. Compared with normal earthquakes, the slip and rupture velocities of both are smaller by many orders of magnitude. But their S/L values, and thus stress drops, are smaller by only one or two orders of magnitude. For a large long-term slow-slip event in the subduction zones: S = 1–50 cm, T = 50–2500 day, L = 40–1000 km, W = 30–750 km, M = 6.0–7.7, VS = 0.01–0.10 cm/d, VR = 0.1–2 km/d, and S/L = 0.1–2 × 10−6. The estimated slip, duration, rupture length, and magnitude values are larger than the short-term events, but the average slip and rupture velocities are much smaller. This difference suggests that the long-term events may have commonly encountered stronger asperities, which can slow down or even break them into smaller short-term events.
- fault zone
- plate interface
- subduction zone
- fault gouge
Tectonic faults may rupture rapidly (seismically) to generate earthquakes or slowly (aseismically) without doing so. During the last two decades, many slow-slip events have been discovered, especially in the subduction zones around the Pacific Ocean [1, 2, 3, 4]. Some of them preceded or followed major earthquakes [5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]. This chapter summarizes kinematic parameters of these slow-slip events reported in the literature and compares them with creep events and shallow slow-slip events observed along the strike-slip faults in California. By such comparison, I hope to better understand not only the physical mechanisms of the different kinds of fault-slip behaviors but also the mechanisms of the related hydrological, geochemical, and geophysical changes often accompanying them [16, 17]. Such understanding, in turn, may help us to explore the possibility of short-term prediction of some earthquakes.
2. Creep events in California
The fact that a tectonic fault may slip slowly was first found on a surface trace of a strike-slip fault in central California . Early measurements by creepmeters showed that the slow-slip motion can occur not only steadily but also episodically in small steps of several millimeters in short durations of a few days with no slip in between . Subsequent measurements by widely distributed networks of creepmeters showed that the occurrence of creep events was quite common along many fault segments in central California, and elsewhere [20, 21, 22].
By studying creep events recorded at neighboring sites, Nason  noticed that they often began at different times, suggesting that a creep event is a rupture propagation process with a velocity of about 1–10 km/day. King et al.  estimated the maximum slip velocity to be about 0.01–1 cm/day. By analyzing creep data recorded at many network sites (Figure 1) and by fitting the creep data to a faulting model , King et al.  found that a large creep event might have a rupture length of several kilometers, an offset of about 1 cm. They also concluded that a creep event was kinematically similar to seismic faulting, but with rates that are five or more orders of magnitude smaller. Figures 2–4 show the records of two creep events and the model fitting of the larger (Figure 2b) by King et al. , who found the following kinematic values: maximum slip S = 0.9 cm, duration T = 2 days, rupture length L = 6 km, rupture width W = 3 km, magnitude M = 4.7, average slip velocity VS = S/T = 0.45 cm/day, average rupture velocity VR = L/T = 3 km/d, and slip/rupture length ratio S/L = 1.5 × 10−6. The S/L ratio, which is a measure of stress drop, is an order of magnitude smaller than that of seismic faulting.
3. Subsurface slow-slip events in California
Subsurface slow-slip event was first observed at San Juan Bautista (SJB) in central California, by using two continuously recording borehole strainmeters . The recorded slip curves showed some kinks, which are probably caused by some higher-resistance patches, for similar kinks were found in a theoretical faulting model by barriers . This event reached an estimated depth of 4 km and lasted about 5 days with an estimated maximum slip of 2.5 cm, a rupture length of 8 km, and a magnitude of 4.8. The kinematic values are comparable to those of the surface creep event described above.
In Parkfield area of California, Guilhem and Nadeau  studied 52 tremor episodes, which may be related to slow-slip events about 25 km deep. They estimated that a typical event has a duration of about 10 days, maximum slip of about 7.8 mm, rupture length of about 25 km, width of 15 km, and equivalent magnitude of 5.0–5.4. Excepting the slip value, it is larger than the surface and subsurface events described above. Similar slow-slip events have been detected along other inland faults also [7, 13].
4. Slow-slip events in Circum-Pacific subduction zones
Since about the beginning of the twenty-first century, with the deployment of an increasing number of geodetic instruments, many below-surface slow-slip events have been detected, especially along plate boundaries in the subduction zones around the Pacific Ocean, where megathrust earthquakes often occur [1, 4, 27, 28, 29, 30]. Most slow-slip events occurred offshore and were relatively far away from onland instruments. In areas where such events were continuously detected by dense networks of geodetic and seismic instruments, the resultant data have been analyzed to estimate their kinematic values [2, 31, 32, 33].
In the Circum-Pacific subduction zones, most observed slow-slip events occur in transition areas downdip the seismogenic areas (asperities) and updip the stable-sliding areas of the plate interfaces (e.g., Figure 5). Except in New Zealand and Costa Rica, they are mostly located quite far from onland instruments, including strainmeters, tiltmeters, and GPS stations [27, 28, 34]. To delineate the kinematic parameters of a slip event, data have to be recorded continuously at multiple sites and inverted with the help of some elastic dislocation models, such as that by Okada . Thus, the estimated kinematic values are rather uncertain. Some slow-slip events occurred in transition areas of plate interfaces updip the seismic asperities also. They have been detected more frequently as more instruments are deployed further offshore [9, 36].
Some slow-slip events were found to be accompanied by seismic tremors and low-frequency/regular earthquakes in/near the same areas of the plate interface [29, 37, 38, 39, 40]. This suggested that these tremors and earthquakes were generated at small asperities swept over by the rupture front of the slow-slip events. Since then, additional information about the slow-slip kinematics has been obtained from the distribution and migration of these events recorded by seismic instruments.
The depths of the observed slow-slip events usually range from 25 to 60 km; the durations in some zones show bimodal distribution of long term (of months to years) and short term (days to weeks). Short-term events in most subduction zones occurred closer to the deeper stable-sliding zone, while long-term events closer to the shallower seismogenic zone (Figure 5) . The situation is somewhat different in New Zealand and Costa Rica, however .
The estimated kinematic parameters are given in the following order: maximum slip S, duration T, rupture length L, width W, magnitude M, average slip velocity Vs = S/T, average rupture velocity VR = L/T, maximum slip/rupture length ratio = S/L.
In the tectonically more complicated Southwest Japan including Tokai region and Kii and Bungo Channels, where quite a few great earthquakes occurred in history, the Pacific plate in the east subducts westward beneath the Philippine Sea plate, which in turn subducts northwestward beneath the Eurasian plate along the Nankai trough and northeastward beneath the Okhotsk plate along the Sagami trough. Many “long-term” and “short-term” slow-slip events at depths of 30–40 km have been observed since 1997.
In the Central
Table 1 gives a summary of the estimated kinematic values of slip S, duration T, rupture length L, rupture width W, and magnitude M, as well as calculated values of slip velocity VS = S/T, rupture velocity VR = L/T, and S/L, which is a measure of stress drop. In this table, a factor of 10−6 is omitted from the S/L values.
|Events||S (cm)||T (day)||L (km)||W (km)||M||S/T (cm/d)||L/T (km/d)||S/L|
|California surface creep||0.9||2||6||3||4.7||0.45||3||1.5|
|SJB subsurface slow slip||2.5||5||8||4||4.8||0.5||1.6||0.31|
|Parkfield deep slow slip||0.8||10||25||15||5.0–5.4||0.08||2.5||0.03|
|Circum-Pacific short term|
|Hikurangi, New Zealand||1.2–24||5–36||50–180||50–90||5.8–7.0||0.24–0.67||5–10||0.24–1.33|
|Northwestern Costa Rica||1.5–15||20–180||30–120||20–40||6.6–6.7||0.07–0.08||0.7–1.5||0.50–1.25|
|Circum-Pacific long term|
|Hikurangi, New Zealand||4–56||50–550||60–200||30–150||6.5–7.2||0.08–0.10||0.36–1.20||0.67–2.80|
Among the short-term slow-slip events included in Table 1, those in New Zealand and Costa Rica occurred updip the seismogenic area of the subduction interface. Yet the estimated kinematic values are comparable to those downdip the seismogenic interface areas in other subduction zones. On the other hand, the kinematic values for central Ecuador are quite different, due to the unusually large slips reported. The same is true with Chile in the case of long-term events, and the opposite is true for the Parkfield events, when compared with two other cases in California. In the following discussion, we shall exclude these three cases from further consideration.
It may be seen that most short-term slow-slip events in the various Circum-Pacific subduction zones have comparable kinematic values: a slip of about 1–20 cm, duration of 2–50 days, rupture length of 20–260 km, width of 10–90 km, magnitude of 5.6–7.0, slip velocity of 0.1–0.8 cm/d, rupture velocity of 2–20 km/d, and an S/L value of 0.1–1.3. Compared with creep and shallow slow-slip events in California, they have larger values in slip, duration, rupture length/width, and magnitude, but comparable values in slip velocity, rupture velocity, and S/L ratio. This result indicates that kinematics of slow-slip events are basically similar, independent of temperature, pressure, and composition of the fault-zone materials, as long as they are mostly velocity-strengthening fault-gouge type; the larger sizes of the subduction events are probably due to their larger inertia associated with larger overburden at greater depth. Compared with normal earthquakes, the slip and rupture velocities of the slow-slip events are all smaller by many orders of magnitude, and the estimated S/L values are smaller by one or two orders of magnitude. Since S/L is proportional to stress drop, this result shows that the stress drops for the slow-slip events are one or two orders of magnitude smaller than normal earthquakes.
The long-term events have large variations in their kinematic values: slip of about 1–50 cm, duration of 50–2500 days, rupture length of 40–1000 km, width of 30–750 km, magnitude of 6.0–7.7, slip velocity of 0.01–0.10 cm/d, rupture velocity of 0.1–2 km/d, and S/L of 0.2–3. Compared with the short-term events, they have larger values in slip, duration, rupture length, and magnitude, comparable values in slip/rupture length ratios (thus stress drops) and smaller values in average slip and rupture velocities. This feature arose may be because they occurred closer to the seismogenic area of the plate interface , which has more asperities to hinder the rupture process or even to break them into smaller events, as shown in the cases of northeast Japan and Bungo Channel. Being more remote from the instruments, they are less distinguishable, thus giving an appearance of slower propagation. This possibility is further supported by some recent analysis of long-term events [109, 110].
The reason why slow-slip events and seismic tremors occur in the transition areas, both downdip and updip the seismogenic area, of a subduction interface (e.g., Figure 5) is not well known, but may possibly be understood by the following consideration of a five-stage evolution of a subducting seafloor, which consists of seamounts of different heights and strengths embedded in sediments at its surface. At the initial stage of subduction, while under the front edge of the accretionary wedge where the temperature and confining pressure are low, the effect of heterogeneity of sliding friction is small, and thus fault slip caused by crustal convergence proceeds in the form of aseismic stable sliding. When the same seafloor subducts further down and encounter larger confining pressure but still relatively low temperature, the friction at the stronger patches (seamounts) begins to show its stick-slip (velocity weakening) feature in sliding, while the sedimentary parts acts like (velocity strengthening) fault gouge. As a relatively strong asperity breaks under increasing shear stress, the rupture propagates slowly into a larger area of interface consists of weaker asperities embedded in compliant gouge materials, thus causing slow-slip events and small earthquakes in the transition zone updip the seismogenic area of the plate interface. When the same seafloor subducts further down to the seismogenic depth, where the confining pressure becomes sufficiently large while the temperature is not, the heterogeneity contrast becomes very sharp, and thus when a strong patch (asperity) breaks, it may cause a rupture to propagate rapidly into a large area of the interface, sweeping through smaller asperities embedded in compliant gouge materials and resulting in a large or even megathrust earthquake in the seismogenic area of the interface. When the seafloor subducts further down and encounter still larger confining pressure and higher temperature, the large asperities may have been worn down by now and become softened, while the surrounding fault-gouge materials further cumulated in volume and strength. When such a weaker asperity breaks, it encounters stronger resistance and thus may cause only a slowly rupturing event in the transition zone of the downdip area; as the rupture sweeps through some even smaller asperities, it may cause seismic tremors and perhaps small earthquakes. When the seafloor subducts further down and encounters still higher confining pressure and temperature at the deepest level of subduction, the asperities may have become sufficiently worn and softened and the gouge materials further cumulated; the frictional heterogeneity may finally become insignificant and thus the sliding becomes stable again.
What further directions should be pursued? Besides acquiring additional high-quality data through more continuous monitoring efforts closer to the events, it is important to analyze the data with appropriate faulting models to better understand the mechanics of slow-slip events and their role as a silent agent in stress adjustment along fault zones. Such knowledge should help us to better understand the occurrence pattern of earthquakes, such as foreshocks, main shocks, aftershocks, earthquake swarm, and earthquake migration , as well as crustal deformation without earthquakes . It may also help us better understand the mechanisms of various earthquake-related hydrological, geochemical, and geophysical changes . Together with better monitoring efforts of such changes, especially those that precede earthquakes [14, 15], it may finally be possible to predict some destructive earthquakes and aftershocks.
Schwartz SY, Rokosky JM. Slow slip events and seismic tremors at circum-Pacific subduction zones. Reviews of Geophysics. 2007; 45(3):RG3004. DOI: 10.1029/2006RG000208
Gao H, Schmidt DA, Welden RJ II. Scaling relationship of source parameters for slow slip events. Bulletin of the Seismological Society of America. 2012; 102:352-360
Liu Y. Source scaling relations and along-strike segmentation of slow slip events in a 3-D subduction fault model. Journal of Geophysical Research. 2014; 119:6512-6533
Obara K, Kato A. Connecting slow earthquakes to huge earthquakes. Science. 2016; 353:253-257
Linde AT, Sack SI. Slow earthquakes and great earthquakes along the Nankai Trough. Earth and Planetary Science Letters. 2002; 203:265-275
Linde AT, Silver PG. Elevation changes and the great 1960 Chilean earthquake: Support for aseismic slip. Geophysical Research Letters. 1989; 16:1305-1308
Bouchon M, Karabulut H, Aktar M, Özalaybey S, Schmittbuhl J, Bouin MP. Extended nucleation of the 1999 Mw 7.6 Izmit earthquake. Science. 2011; 331(6019):877-880
Kato A, Obara K, Igarashi T, Tsuruoka H, Nakagawa S, Hirata N. Propagation of slow slip leading to the 2011 Mw 9.0 Tohoku-Oki earthquake. Science. 2012; 335:705-798
Ito Y, Hino R, Fujimoto H, Osada Y, Inazu D, Ohta Y. Episodic slow slip events in the Japan subduction zone before the 2011 Mw 9.0 Tohoku-Oki earthquake. Tectonophysics. 2013; 600:14-26
Graham SE, DeMets C, Cabral-Cano E, Kostoglokov V, Walpersdorf A, Cotte M, et al. GPS constraints on the 2011-2012 Oaxaca slow slip event that preceded the 2012 March 20 Ometepec earthquake, southern Mexico. Geophysical Journal International. 2014; 197:1593-1607. DOI: 10.1093/gji/ggu019
Kato A, Nakagawa S. Multiple slow-slip events during a foreshock sequence of the 2014 Iquique, Chile Mw 8.1 earthquake. Geophysical Research Letters. 2014; 41:5420-5427. DOI: 10.1002/2014GL061138
Uchita N, Iinuma T, Nadeau RM, Burgmann R, Hino R. Periodic slow slip triggers megathrust zone earthquakes in northeastern Japan. Science. 2016; 351:488-492
Borghi A, Aoudia A, Javed F, Barzaghi R. Precursory slow-slip loaded the 2009 L'Aquila earthquake sequence. Geophysical Journal International. 2016; 205:776-784. DOI: 10.1093/gji/ggw046
King C-Y, Chia Y. Anomalous stream-flow and water-level changes before the 1999 M7.6 Chi-Chi earthquake in Taiwan: Possible mechanisms. Pure and Applied Geophysics. 2018; 175:29-38. DOI: 10.1007/s00024-017-1737-1
King C-Y. Characteristics of a sensitive well showing pre-earthquake water-level changes. Pure and Applied Geophysics. 2018; 175:5-18. DOI: 10.1007/s00024-018-1855-4
King C-Y, Manga M. Hydrological, geochemical and geophysical changes related to earthquakes and slow-slip events. Pure and Applied Geophysics. 2018; 175:1-3. DOI: 10.1007/s00024-018-1923-9
Ouzounov D, Pulinets S, Hattori K, Taylor P, editors. Pre-Earthquake Processes: A Multi-disciplinary Approach to Earthquake Prediction Studies. Washington: AGU/Wiley; 2018. 385 p
Steinbrugge KV, Zacher EG. Creep on the San Andrea fault. Bulletin of the Seismological Society of America. 1960; 50:389-396
Tocher D. Creep on the San Andreas Fault. Bulletin of the Seismological Society of America. 1960; 50:396-404
Nason RD. Earthq. Res. In: ESSA, 1969-70, ESSA Tech. Rep. ERL 1970; 182-ESL 11: 12-15
Schulz SS, Mavko GM, Burford RO, Stuart WD. Long-term fault creep observations in central California. Journal of Geophysical Research: Solid Earth. 1982; 87(B8):6977-6982
Harris RA. Large earthquakes and creeping fault. Reviews of Geophysics. 2017; 55:169-198
King C-Y, Nason RD, Tocher D. Characteristics of fault creep. Earthq. Res. In: ESSA, 1969-1970, ESSA Tech 'Rep. ERL 182-ESL 11: 15-18
King C-Y. Particle motion along a kinematic fault model. Bulletin of the Seismological Society of America. 1970; 60:491-501
King CY, Nason RD, Tocher D. Kinematics of fault creep. Philosophical Transactions. Royal Society of London. 1973; A.274:355-360
Linde AT, Gladwin M, Johnston M, Gwyther R, Bilham R. A slow earthquake sequence on the San Andreas Fault. Nature. 1996; 383:65-68
King C-Y. A shallow faulting model. Bulletin of the Seismological Society of America. 1972; 62:551-559
Guilhem A, Nadeau RM. Episodic tremors and deep slow-slip events in Central California. Earth and Planetary Science Letters. 2012; 357-358:1-10
Hirose H, Hirahara K, Kimata F, Fujii N, Miyazaki S. A slow thrust event following the two 1996 Hyuganada earthquakes beneath the Bungo Channel, southwest Japan. Geophysical Research Letters. 1999; 26:3237-3240
Drager H, Wang K, James TS. A silent slip event on the deeper Cascadia subduction interface. Science. 2001; 292:1525-1528
Obara K. Nonvolcanic deep tremor associated with subduction in southwest Japan. Science. 2002; 296(5573):1679-1681
Beroza GC, Ide S. Slow earthquakes and nonvolcanic tremor. Annual Review of Earth and Planetary Sciences. 2011; 39:271-296
Ide S, Beroza GC, Shelly DR, Uchide T. A scaling law for slow earthquakes. Nature. 2007; 447:76-79. DOI: 10.1038/nature05780
Obara K. Phenomenology of deep slow earthquake family in southwest Japan: Spatiotemporal characteristics and segmentation. Journal of Geophysical Research. 2010; 115:B00A25. DOI: 10.1029/2008JB006048
Peng Z, Gomberg J. An integrated perspective of the continuum between earthquakes and slow-slip phenomena. Nature Geoscience. 2010; 3:599-607. DOI: 10.1038/ngeo940
Heki K, Miyazaki S, Tsuji H. Silent fault slip following an interplate thrust earthquake at the Japan Trench. Nature. 1997; 386:595-598
Okada Y. Surface deformation due to shear and tensile faults in a half-space. Bulletin of the Seismological Society of America. 1985; 75(4):1135-1154
Nakano M, Hori T, Araki E, Kodaira S, Ide S. Shallow very-low-frequency earthquakes accompany slow slip events in the Nankai subduction zone. Nature Communications. 2018; 9(1): Article number 984
Obara K, Hirose H, Yamamizu F, Kasaqhara A. Episodic slow-slip events accompanied by non-volcanic tremors in southwest Japan subduction zone. Geophysical Research Letters. 2004; 31(23):L23602. DOI: 10.1029/2004GL020848
Rogers G, Drager H. Episodic tremors and slip on the Cascadia subduction zone: The chatter of silent slip. Science. 2003; 330:1942-1943
Hirose H, Obara K. Short-term slow slip and correlated tremor episodes in the Tokai region, central Japan. Geophysical Research Letters. 2006; 33:L17311. DOI: 10.1029/2006GL026579
Shelly DR, Beroza GC, Ide S, Nakamula S. Low-frequency earthquakes in Shikoku, Japan, and their relationship to episodic tremor and slip. Nature. 2006; 442:188-191
Rolandone F, Nocquet JM, Mothes PA, Jarrin P, Vallée M, Cubas N, et al. Areas prone to slow slip events impede earthquake rupture propagation and promote afterslip. Science Advances. 2018; 4(1):eaao6596
Wallace LM, Beavan J, Bannister S, Williams C. Simultaneous long-term and short-term slow slip events at the Hikurangi subduction margin, New Zealand: Implications for processes that control sloNaikai subduction w slip event occurrence, duration, and migration. Journal of Geophysical Research. 2012; 117:B11402. DOI: 10.1029/2012JB009489
Ozawa S, Nishimura T, Munekane H, Suito H, Kobayashi T, Tobita M, et al. Preceding, coseismic, and postseismic slips of the 2011 Tohoku earthquake, Japan. Journal of Geophysical Research: Solid Earth. 2012; 117(B7):B07404
Hasegawa A, Yoshida K. Preceding seismic activity and slow slip events in the source area of the 2011 Mw 9.0 Tohoku-Oki earthquake: A review. Geoscience Letters. 2015; 2(1):1-13. DOI: 10.1186/s40562-015-0025-0
Yokota Y, Koketsu K. A very long-term transient event preceding the 2011 Tohoku earthquake. Nature Communications. 2015; 6:5934
Ozawa S, Miyazaki S, Hatanaka Y, Imakiire T, Kaidzu M, Murakami M. Characteristic silent earthquakes in the eastern part of the Boso Peninsula, central Japan. Geophysical Research Letters. 2003; 30(6):1283. DOI: 101029/2002GL016665
Sagiya T. Interplate coupling in the Kanto District, central Japan, and the Boso Peninsula silent earthquake in May 1996. Pure and Applied Geophysics. 2004; 161:2327-2342
Okutani T, Ide S. Statistic analysis of swarm activities around the Boso Peninsula, Japan: Slow slip events beneath Tokyo Bay? Earth, Planets and Space. 2011; 63(5):419-426
Davis E, Kinoshita M, Becker K, Wang K, Asano Y, Ito Y. Episodic deformation and inferred slow slip at the Nankai subduction zone during the first decade of CORK borehole pressure and VLFE monitoring. Earth and Planetary Science Letters. 2013; 368:110-118
Hirose H, Matsuzawa T, Kimura T. The Boso slow slip events in 2007 and 2011 as a driving process for the accompanying earthquake swarm. Geophysical Research Letters. 2014; 41:2778-2785. DOI: 10.1002/2014GL059791
Ozawa S. Shortening of recurrence interval of Boso slow slip events in Japan. Geophysical Research Letters. 2014; 41:2762-2768. DOI: 10.1002/2014GL060072
Miyazaki S, Segall P, McGuire JJ, Kato T, Hatanaka Y. Spatial and temporal evolution of stress and slip rate during the 2000 Tokai slow earthquake. Journal of Geophysical Research. 2006; 111:B03409. DOI: 10.1029/2004JB003426
Ohta Y, Kimata F, Sagiya T. Reexamination of the interplate coupling in the Tokai region, central Japan, based on the GPS data in 1997-2002. Geophysical Research Letters. 2004; 31:L24604. DOI: 101029/2004GL021404
Ozawa S, Murakami M, Kaidzu M, Tada T, Sagiya T, Hatanaka T, et al. Detection and monitoring of ongoing aseismic slip in Tokai region, central Japan. Science. 2002; 298:1295-1298
Yamamoto E, Matsumura S, Ohkubo T. A slow slip event in the Tokai area detected by tilt and seismic observation and its possible recurrence. Earth, Planets and Space. 2005; 57:917-923
Kobayashi A. A long-term slow slip event from 1996 to 1997 in the Kii channel, Japan. Earth, Planets and Space. 2014; 66(1):1-7
Itaba S, Ando R. A slow slip event triggered by teleseismic surface waves. Geophysical Research Letters. 2011; 38:L21306. DOI: 10.1029/ 2011GL049593
Hirose H, Obara K. Repeating short- and long-term events with deep tremor activity around the Bungo Channel region, southwest Japan. Earth, Planets and Space. 2005; 57:961-972
Miyazaki S, McGuire JJ, Segall P. A transient subduction zone slip episode in southwest Japan observed by the nationwide GPS array. Journal of Geophysical Research. 2003; 108(B2):2087. DOI: 10.1029/2001JB000456
Ozawa S, Hatanaka Y, Kaidzu M, Murakami M, Imakiire T, Ishigaki Y. Aseismic slip and low-frequency earthquakes in the Bungo Channel, southwestern Japan. Geophysical Research Letters. 2004; 31:L07609. DOI: 10.1029/2003GL019381
Ozawa S, Yarai H, Imakiire T, Tobita M. Spatial and temporal evolution of the long-term slow slip in the Bungo Channel, Japan. Earth, Planets and Space. 2013; 65(2):67-73
Yarai H, Ozawa S. Quasi-periodic slow slip events in the afterslip area of the 1996 Hyuga-nada earthquakes, Japan. Journal of Geophysical Research—Solid Earth. 2013; 118(5):2512-2527. DOI: 10.1002/jgrb.50161
Nishimura T, Matsuzawa T, Obara K. Detection of short-term slow slip events along the Nankai Trough, southwest Japan, using GNSS data. Journal of Geophysical Research: Solid Earth. 2013; 118(6):3112-3125
Asano Y, Obara K, Matsuzawa T, Hirose H, Ito Y. Possible shallow slow slip events in Hyuga-nada, Nankai subduction zone, inferred from migration of very low frequency earthquakes. Geophysical Research Letters. 2015; 42:331-338. DOI: 10.1002/2014GL062165
Yoshioka S, Matsuoka Y, Ide S. Spatiotemporal slip distributions of three long-term slow slip events beneath the Bungo Channel, southwest Japan, inferred from inversion analyses of GPS data. Geophysical Journal International. 2015; 201(3):1437-1455
Takagi R, Obara K, Maeda T. Slow slip event within a gap between tremor and locked zones in the Nankai subduction zone. Geophysical Research Letters. 2016; 43(3):1066-1074
Nakata R, Hino H, Kuwatani T, Yoshioka S, Okada M, Hori T. Discontinuous boundaries of slow slip events beneath the Bungo Channel, southwest Japan. Scientific Reports. 2017; 7(1):6129
Douglas A, Beavan J, Wallace L, Townend J. Slow slip on the northern Hikurangi subduction interface, New Zealand. Geophysical Research Letters. 2005; 32:L16305. DOI: 10.1029/2005GL023607
Franco SI, Kostoglodov V, Larsen KM, Manea VC, Manea M, Santiago JA. Propagation of the 2001– 2002 silent earthquake and interplate coupling in the Oaxaca subduction zone, Mexico. Earth, Planets and Space. 2005; 57:973-985
Kostoglodov V, Singh SK, Santiago JA, Franco SI, Larson KM, Lowry AR, et al. A large silent earthquake in the Guerrero seismic gap, Mexico. Geophysical Research Letters. 2003; 30(15):1807. DOI: 10.1029/2003GL017219
Larson KM, Kostoglodov V, Lowry A, Hutton W, Sanchez O, Hudnut K, et al. Crustal deformation measurements in Guerrero, Mexico. Journal of Geophysical Research. 2004; 109:B04409. DOI: 10.1029/2003JB002843
Lowry AR, Larson KM, Kostoglodov V, Bilham R. Transient fault slip in Guerrero, southern Mexico. Geophysical Research Letters. 2001; 28:3753-3756
Lowry AR, Larson KM, Kostoglodov V, Sanchez O. The fault slip budget in Guerrero, southern Mexico. Geophysical Journal International. 2005; 200:1-15
Wallace LM, Beavan J. Diverse slow slip behavior at the Hikurangi subduction margin, New Zealand. Journal of Geophysical Research. 2010; 115:B12. DOI: 10.1029/2010JBB007717
Wallace L, Webb PC, Ito Y, Mochizuki K, Hino R, Henrys S, et al. Slow slip near the trench at the Hikurangi subduction zone, New Zealand. Science. 2016; 352:701-704. DOI: 10.1126/science.aaf2349
Wallace LM, Eberhart-Phillips D. Newly observed, deep slow slip events at the central Hikurangi margin, New Zealand: Implications for downdip variability of slow slip and tremor, and relationship to seismic structure. Geophysical Research Letters. 2013; 40:5393-5398. DOI: 10.1002/2013GL057682
Bartlow NM, Wallace MW, Beavan RJ, Bannister S, Segall P. Time-dependent modeling of slow slip events and associated seismicity and tremor at the Hikurangi subduction zone, New Zealand. Journal of Geophysical Research. 2014; 119:734-753. DOI: 10.1002/2013JB010609
Saffer D, Wallace LM. The frictional, hydrologic, metamorphic and thermal habitat of shallow slow earthquakes. Nature Geoscience. 2015; 8:594-600. DOI: 10.1038/ngeo2490
Wei M, McGuire JJ, Richardson E. A slow slip event in the south central Alaska Subduction Zone and related seismicity anomaly. Geophysical Research Letters. 2012; 39:L15309. DOI: 10.1029/2012GL052351
Fu Y, Freymueller JT. Repeated large slow slip events at the southcentral Alaska subduction zone. Earth and Planetary Science Letters. 2013; 375:303-311
Fu Y, Liu Z, Freymueller JT. Spatiotemporal variations of slow slip event between 2008 and 2013 in the southcentral Alaska subduction zone. Geochemistry, Geophysics, Geosystems. 2015; 16:2450-2461
Wang K, Wells R, Mazzotti S, Hyndman RD, Sagiya T. A revised dislocation model of interseismic deformation of the Cascadia subduction zone. Journal of Geophysical Research. 2003; 108(B1):2026. DOI: 10.1029/2001JB001227
Drager H, Wang K, Rogers G. Geodetic and seismic signatures of episodic tremor and slip in the northern Cascadia subduction zone. Earth, Planets and Space. 2004; 56:1143-1150
McGuire JJ, Segall P. Imaging of aseismic fault slip transients recorded by dense geodetic networks. Geophysical Journal International. 2003; 155:778-788
Melbourne TI, Szeliga WM, Miller MM, Santillan VM. Extent and duration of the 2003 Cascadia slow earthquake. Geophysical Research Letters. 2005; 32:L04301. DOI: 10.1029/ 2004GL021790
Szeliga WT, Melbourne T, Santillan M, Miller M. GPS constraints on 34 slow slip events within the Cascadia subduction zone 1997-2005. Journal of Geophysical Research. 2008; 113:B04404. DOI: 10.1029/2007JB004948
McCaffrey R. Time-dependent inversion of three component continuous GPS for steady and transient sources in northern Cascadia. Geophysical Research Letters. 2009; 36:L07304. DOI: 10.1029/2008GL036784
Schmidt D, Gao H. Source parameters and time-dependent slip distributions of slow slip events on the Cascadia subduction zone from 1998 to 2008. Journal of Geophysical Research. 2010; 115:B00A18. DOI: 10.1029/2008JB006045
Wech AG, Bartlow NM. Slip rate and tremor genesis in Cascadia. Geophysical Research Letters. 2014; 41:392-398. DOI: 10.1002/2013GL058607
Schmalzle GM, McCaffrey R, Creager KC. Central Cascadia subduction zone creep. Geochemistry, Geophysics, Geosystems. 2014; 15:1515-1532. DOI: 10.1002/2013GC005172
Hutchison AA, Ghosh A. Very low frequency earthquakes spatiotemporally asynchronous with strong tremor during the 2014 episodic tremor and slip event in Cascadia. Geophysical Research Letters. 2016; 43:6876-6882. DOI: 10.1002/2016GL069750
Radiguet M, Cotton F, Vergnolle M, Campilo M, Vallete B, Kostoglodov V, et al. Spatial and temporal evolution of a long term slow slip event: The 2006 Guerrero slow slip event. Geophysical Journal International. 2011; 184(2):816-828
Radiquet M, Cotton F, Vergnolle M, Campillo M, Walpersdolf A, Cotte N, et al. Slow slip events and strain accumulation in the Guerrero gap, Mexico. Journal of Geophysical Research. 2012; 117:B04305. DOI: 10.1029/2011JB008801
Rousset B, Campillo M, Lasserre C, Frank WB, Cotte N, Walpersdorf A, et al. A geodetic matched filter search for slow slip with application to the Mexico subduction zone. Journal of Geophysical Research: Solid Earth. 2017; 122(12):10-498
Lundgren P, Protti M, Donnellan A, Heflin M, Hernandez E, Jefferson D. Seismic cycle and plate margin deformation in Costa Rica: GPS observations from 1994 to 1997. Journal of Geophysical Research. 1999; 104:28915-28928
Iinuma T, Protti M, Obana K, Gonzalez V, van der Laat R, Kato T, et al. Inter-plate coupling in the Nicoya Peninsula, Costa Rica, as deduced from a trans-peninsula GPS experiment. Earth and Planetary Science Letters. 2004; 223:203-212
Norabuena E et al. Geodetic and seismic constraints on some seismogenic zone processes in Costa Rica. Journal of Geophysical Research. 2004; 109:B11403. DOI: 10.1029/2003JB002931
Brown KM, Tryon MD, DeShon HR, Dorman LM, Schwartz SY. Correlated transient fluid pulsing and seismic tremor in the Costa Rica subduction zone. Earth and Planetary Science Letters. 2005; 238:189-203
Outerbridge K C, Dixon TH, Schwartz SY, Walter JI, Protti M. A tremor and slip event on the Cocos-Caribbean Subduction zone as measured by a global positioning system (GPS) and seismic network on the Nicoya Peninsula, Costa Rica. Journal of Geophysical Research. 2010; 115:B10408. DOI: 10.1029/2009JB006845
Jiang Y, Wdowinski S, Dixon TH, Hackl M, Protti M, Gonzalez V. Slow slip events in Costa Rica detected by continuous GPS observations, 2002-2011. Geochemistry, Geophysics, Geosystems. 2012; 13(4):Q04006. DOI: 10.1029/2012GC004058
Voss NK, Malservisi R, Dixon TH, Protti M. Slow slip events in the early part of the earthquake cycle. Journal of Geophysical Research. 2017; 122:6773-6786. DOI: 10.1002/2016JB013741
Valée M, Nocquet J-M, Battaglia J, Font Y, Segovia M, Régnier M, et al. Intense interface seismicity triggered by a shallow slow slip event in the Central Ecuador subduction zone. Journal of Geophysical Research. 2013; 118:2965-2981
Vaca S, Vallée M, Nocquet J-M, Battaglia J, Régnier M. Recurrent slow slip events as a barrier to the northward rupture propagation of the 2016 Pedernales earthquake (Central Ecuador). Tectonophysics. 2018; 724-725:80-92. DOI: 10.1016/j.tecto.2017.12.012
Yagi Y, Okuwaki R, Enescu B, Hirano S, Yamagami Y, Endo S, et al. Rupture process of the 2014 Iquique Chile earthquake in relation with the foreshock activity. Geophysical Research Letters. 2014; 41(12):4201-4206
Kato A, Fukuda JI, Kumazawa T, Nakagawa S. Accelerated nucleation of the 2014 Iquique, Chile Mw 8.2 earthquake. Scientific Reports. 2016; 6:24792
Klein E, Duputel Z, Zigone D, Vigny C, Boy JP, Doubre C, et al. Deep transient slow slip detected by survey GPS in the region of Atacama, Chile. Geophysical Research Letters. 2018; 45(22):12-23. DOI: 10.1029/2018GL080613
Walpersdorf A, Cotte N, Kostoglodov V, Vergnolle M, Radiguet M, Santiago JA, et al. Two successive slow slip events evidenced in 2009-2010 by a dense GPS network in Guerrero, Mexico. Geophysical Research Letters. 2011; 38(15)
Frank WB, Rousset B, Lasserre C, Campillo M. Revealing the cluster of slow transients behind a large slow slip event. Science Advances. 2018; 4(5):eaat0661
King CY, Ma Z. Migration of historical earthquakes in California. Pure and Applied Geophysics. 1988; 127(4):627-639
Shi Z, Wang G, Liu C, Che Y. Tectonically induced anomalies without large earthquake occurrences. Pure and Applied Geophysics. 2017; 175:107-120