Transient deformation has been observed in a number of different types of tectonic environments. These transient deformation signals are often observed using continuous GPS (CGPS) position time-series observations. Examining transient deformation using CGPS time-series is problematic due to the, often, low signal-to-noise ratios and variability in duration of transient motions observed. A technique to estimate a continuous velocity function from noisy CGPS coordinate time-series of is examined. The resolution of this technique is dependent on the signal-to-noise ratio and the duration or frequency content of the transient signal being modeled. Short period signals require greater signal-to-noise ratios for effective resolution of the actual transient signal. The technique presented here is similar to a low-pass filter but with a number of advantages when working with CGPS data. Data gaps do not adversely impact the technique but limit resolution near the gap epochs, if there is some a priori knowledge of the noise contained within the time-series this information can be included in the model, and model parameter uncertainties provide information on the uncertainty of instantaneous velocity through time. A large transient has been observed in the North-American stable continental interior as a significant increase in the number and moment release of earthquakes through time. This increase in the number of earthquakes has been suggested to be largely related changes in oil and gas production activities within the region as triggered or induced seismicity, primarily from fluid injection. One of the first observed cases of triggered earthquakes from hydraulic fracturing where the earthquakes were large enough to be felt by local residents is documented. The multiple strong temporal and spatial correlations between these earthquakes indicate that hydraulic fracturing in a nearby well likely triggered the earthquake sequence. The largest magnitude earthquake in this sequence was a magnitude 2.9 with 16 earthquakes greater than magnitude 2. The earthquakes in this sequence occurred within 2.5 km of the hydraulic fracturing operation and focal depths are similar to the depths of hydraulic fracturing treatment depths. In addition to the documentation of a transient earthquake signal associated with hydraulic fracturing, the observed focal mechanisms throughout Oklahoma are documented. These focal mechanisms were used to examine the maximum horizontal stress orientations and active fault orientations associated with the increased rates of seismicity observed in the region. Generally, active-fault orientations and the stresses are consistent through broad portions of Oklahoma with one exception, the ongoing Jones earthquake sequence in central Oklahoma that started in 2009. In the Jones earthquake sequence a bi-modal distribution of focal mechanisms are observed. One orientation of active faults observed in the Jones earthquake sequence would not be expected to be active in the observed regional stress field. This unfavorably oriented set of faults appear to be pre-existing structures and activity on these structures may suggest that pore-pressure increases in the sub-surface due to fluid injection in the area make it possible for faults that are not optimally oriented within the regional stress-field to reactivate.

3 Title: Moment-tensor inversion of earthquakes in Greece, method ISOLA Author: Dana Červinková Department: Department of Geophysics Supervisor: Prof. RNDr. Jiří Zahradník, DrSc. Supervisor's e-mail address: jz@karel.troja.mff.cuni.cz Abstract: The possibility of obtaining a reliable moment tensor using a low-frequency waveform inversion from a single seismic station is studied. Deviatoric part of the moment tensor is described in usual way, using its orientation (angles strike, dip, rake), scalar seismic moment M0 and the double-couple percentage (DC%), and also by means of the coefficients of linear combination of elementary mechanisms. We estimate the formal error of the coefficients and study conditionality of the inverse problem. Data from earthquakes Trichonis (Mw = 5.2, April 2007) and Leonidio (Mw = 6.2, January 2008), Greece, are processed using software ISOLA (Sokos and Zahradník). The moment tensor is calculated from many stations and its stability is tested. This reference solution is compared to those independently obtained from single stations. Synthetic tests are performed to understand why the single-station estimates are sufficient for Trichonis, but not for Leonidio, paying attention to the focal depth, station azimuth and epicentral distance. It is found that the depth is crucial at...

Arc–continent collision is a significant plate boundary process that results in crustal growth. Since the early stages of evolution are often obscured in mature orogens, more complete understanding of the processes involved in arc–continent collision require study of young, active collision settings. The Banda Arc presents an exceptional opportunity to study a young arc–continent collision zone. This thesis presents aspects of the geology and geochronology of Ataúro and the Aileu Complex of Timor-Leste, and the tectonics of the Banda Arc. / U–Pb dating of detrital zircons from the Aileu Complex by LA-ICPMS show major age modes at 270–440 Ma, 860–1240 Ma and 1460–1870 Ma. The youngest zircon populations indicate a maximum depositional age of 270 Ma. The detrital zircon age populations and evidence for juvenile sediments within the sequence favours a synorogenic setting of deposition of sediments sourced from an East Malaya – Indochina terrane. / Previous uncertainty in aspects of the cooling history for the Aileu Complex is resolved with 39Ar/40Ar geochronology of hornblende. Cooling ages of 6–10 Ma are established, with the highest metamorphic grade parts of the Complex yielding the older ages. Cooling ages of 10 Ma imply that metamorphism of the Aileu Complex must have commenced by at least ~12 Ma. Metamorphism at this time is attributed to an arc setting rather than the direct result of collision of the Australian continent with the Banda Arc, an interpretation consistent with the new provenance data. / Geological mapping of Ataúro, an island in the volcanic Banda Arc north of Timor, reveals a volcanic history of bi-modal subaqueous volcanism. 39Ar/40Ar geochronology of hornblende from dacitic lavas confirms that volcanism ceased by ~3 Ma. Following the cessation of volcanism, coral reef marine terraces have been uplifted to elevations of 700 m above sea level. Continuity of the terraces at constant elevations around the island reflects regional-scale uplift most likely linked to sublithospheric processes such as slab detachment. / North of Timor, the near complete absence of intermediate depth seismicity beneath the inactive segment of the arc is attributed to a slab window that has opened in the collision zone and extends to 350 km below the surface. Differences in seismic moment release around this slab window indicate asymmetric rupture, propagating to the east at a much faster rate than to the west. If the lower boundary of this seismic gap signifies the original slab rupture then the slab window represents ~4 m.y. of subsequent subduction and implies that collision preceded the end of volcanism by at least 1 m.y. / Variations in seismic moment release and stress state across the transition from subduction of oceanic crust to arc–continent collision in the Banda Arc are investigated using earthquake catalogues. It is shown that the slab under the western Savu Sea is unusual in that intermediate depth (70–300 km) events indicate that the slab is largely in down-dip compression at this depth range, beneath a region of the arc that has the closest spacing of volcanoes in the Sunda–Banda arc system. This unusual state of stress is attributed to subduction of a northern extension of the Scott Plateau. Present day deformation in the Savu Sea region may be analogous with the earliest stages of collision north of Timor.

Fault planes of large earthquakes incorporate inhomogeneous structures. This can be observed in teleseismic studies through the spatial distribution of slip and seismic moment release caused by the mainshock. Both parameters are often concentrated on patches on the fault plane with much higher values for slip and moment release than their adjacent areas. These patches are called asperities which obviously have a strong influence on the mainshock rupture propagation. Condition and properties of structures in the fault plane area, which are responsible for the evolution of such asperities or their significance on damage distributions of future earthquakes, are still not well understood and subject to recent geo-scientific studies. <br><br> In the presented thesis asperity structures are identified on the fault plane of the M_w=8.0 Antofagasta earthquake in northern Chile which occurred on 30th of July, 1995. It was a thrust-type event in the seismogenic zone between the subducting pacific Nazca plate and the overriding South American plate. In cooperation of the German Task Force for Earthquakes and the CINCA'95 project a network of up to 44 seismic stations was set up to record the aftershock sequence. The seaward extension of the network with 9 OBH stations increased significantly the precision of hypocenter determinations. They were distributed mainly on the fault plane itself around the city of Antofagasta and Mejillones Peninsula. <br><br> The asperity structures were recognized here by the spatial variations of local seismological parameters; at first by the spatial distribution of the seismic b-value on the fault plane, derived from the magnitude-frequency relation of Gutenberg-Richter. The correlation of this b-value map with other parameters like the mainshock source time function, the gravity isostatic residual anomalies, the aftershock radiated seismic energy distribution and the vp/vs ratios from a local earthquake tomograhpy study revealed some ideas about the composition and asperity generating processes. The investigation of 295 aftershock focal mechanism solutions supported the resulting fault plane structure and proposed a 3D similar stress state in the area of the Antofagasta fault plane. / Die Bruchflaeche grosser Erdbeben umfasst inhomogene Strukturen, die bisher hauptsaechlich in teleseismischen Untersuchungen nachgewiesen werden konnten. Haeufig werden begrenzte Bereiche auf einer Bruchflaeche beobachtet, die durch eine starke Konzentration des freigesetzten seismischen Moments und durch grosse Dislokationen gekennzeichnet sind. Diese Bereiche werden als 'asperities' bezeichnet, die offensichtlich starken Einfluss auf den Bruchverlauf des Hauptbebens ausueben. Beschaffenheit und Eigenschaften der Strukturen in einem Herdgebiet, die verantwortlich sind fuer die Bildung solcher 'asperities' und deren eventueller Bedeutung fuer Schadensverteilungen in zukuenftigen Erdbeben, sind Gegenstand aktueller geowissenschaftlischer Untersuchungen. <br><br> In der vorliegenden Arbeit werden 'asperity'-Strukturen auf der Bruchflaeche des M_w=8.0 Antofagasta Erdbebens vom 30. Juli 1995 im Norden Chiles identifiziert. Es handelt sich hierbei um ein typisches Subduktionsbeben mit Aufschiebungscharakter, das in der seismogenen Zone zwischen der abtauchenden pazifischen Nazca-Platte und der ueberschiebenden suedamerikanischen Platte stattfand. Durch die Zusammenarbeit der Deutschen Task Force fuer Erdbeben und dem sich waehrend des Bebens bereits vor Ort befindlichen CINCA '95 Projektgruppe, konnte ein bis zu 44 Stationen umfassendes seismologisches Netzwerk zur Registrierung der Nachbeben errichtet werden. Vor allem die seeseitige Erweiterung des Netzes durch 9 OBH Stationen trug zur hohen Praezision der Hypozentrenbestimmung der Nachbeben bei, die sich hauptsaechlich auf der Bruchflaeche und damit im Kuestenbereich um die Stadt Antofagasta und der noerdlich gelegenen Halbinsel Mejillones verteilten. <br><br> Die 'asperity'-Strukturen konnten mittels raeumlicher Variationen von lokalen seismologischen Parametern erkannt werden; zunaechst durch die Verteilung des seimologischen b-Wertes auf der Bruchflaeche aus der Magnituden-Haeufigkeitsbeziehung von Gutenberg-Richter. Durch die Korrelation dieser Verteilung mit Parametern wie der Momentenrate aus dem Hauptbeben, der isostatischen Restanomalien des Gravitationsfeldes, der Verteilung der abgestrahlten seismischen Energie durch die Nachbeben und der vp/vs-Verhaeltnisse aus einer lokalen Erdbebentomographie konnten Rueckschluesse auf die Beschaffenheit und damit den Bildungsprozess der asperities gezogen werden. Die Untersuchung der Herflaechenloesungen die fuer 295 Nachbeben bestimmt wurden, ergab eine indirekte Bestaetigung der gefundenen Strukturen und wies auf die Existenz eines 3D Spannungszustands im Bereich der Bruchflaeche des Antofagasta Bebens hin.

Made available in DSpace on 2015-02-24T19:48:44Z (GMT). No. of bitstreams: 1 HelenoCLN_TESE.pdf: 5085114 bytes, checksum: 8f73b093043e3323a8310182a887e244 (MD5) Previous issue date: 2013-08-16 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This thesis presents and discusses the results of the various seismic areas in the State of Pernambuco, with the aim of having a vision of regional seismicity and its causes. To the papers published in journals were added two new original works submitted to international journals, dealing with seismic areas located in the counties of S?o Caetano, Cupira, and Agrestina. All seismic areas mentioned in this thesis are located on the Pernambuco Lineament and its surroundings (both in branches or single faults within 40 km of it). The Pernambuco Lineament is a Neoproterozoic shear zone of continental-scale that deformed the Borborema Province, and presents as branches, shear zones with NE-SW direction. The new submitted papers are from the analysis of data collected by three local networks of stations that operated in the following areas: network SO07 (seismicity in the district of Santa Luzia - S?o Caetano, 2007), network BM10 (data from seismic areas of Serra Verde ( Cupira) and Barra do Chata (Agrestina), in 2010), network SO10 (seismicity near the urban center of S?o Caetano in 2010). These data were used for determining the hypocenters and focal mechanisms in order to discuss the relationship between the seismicity and geological features of the area. The new mechanisms obtained, as well as the previously published allowed the determination of the direction of the average stress in the region. The direction of stress in the region involving the various seismic areas, now or previously studied, is quite stable and approximate EW direction (SHmax). The correlation between seismicity and geological features is observed on the lineament and north of it. In the south (Cupira and Agrestina), in seismic areas nearby shear zones NE-SW, there is no correlation and seismogenic EW normal faults are active and its motion is compatible with regional stresses. It is probable that these active faults are more recent than the Neoproterozoic, probably of the Cretaceous period, when the last great movement of the Pernambuco Lineament occurred / Nesta tese s?o apresentados e discutidos os resultados do estudo de diversas ?reas s?smicas no Estado de Pernambuco com o objetivo de se ter uma vis?o regional da sismicidade e suas causas. Aos trabalhos j? publicados em revistas foram acrescentados dois novos trabalhos originais, submetidos a peri?dicos internacionais, abordando as ?reas s?smicas localizadas nos munic?pios de S?o Caetano, Cupira e Agrestina. Todas as ?reas s?smicas abordadas nesta tese est?o situadas sobre o Lineamento Pernambuco ou seu entorno (seja em ramifica??es ou falhas isoladas a menos de 40 km do mesmo). O Lineamento Pernambuco ? uma zona de cisalhamento Neoproteroz?ica de escala continental que deformou a Prov?ncia Borborema e que apresenta, como ramifica??es, zonas de cisalhamento com dire??o NE-SW. Os novos trabalhos submetidos s?o decorrentes da an?lise de dados coletados por tr?s redes de esta??es que operaram nas seguintes ?reas: rede SO07 (sismicidade no distrito de Santa Luzia - S?o Caetano, em 2007); rede BM10 (dados das ?reas s?smicas de Serra Verde (Cupira) e Barra do Chata (Agrestina), em 2010); rede SO10 (sismicidade pr?xima ao centro urbano de S?o Caetano, em 2010). Esses dados foram utilizados na determina??o dos hipocentros e mecanismos focais visando discutir a correla??o entre a sismicidade e as principais fei??es geol?gicas da regi?o. Os novos mecanismos obtidos, bem como os anteriormente publicados permitiram a determina??o da dire??o do esfor?o m?dio na regi?o. A dire??o dos esfor?os na regi?o envolvendo as diversas ?reas s?smicas, agora ou anteriormente estudadas, ? bastante est?vel e de dire??o aproximada EW (SHmax). A correla??o entre a sismicidade e fei??es geol?gicas ? observada sobre o lineamento e ao norte do mesmo. Ao sul (Cupira e Agrestina), em ?reas s?smicas pr?ximas a zonas de cisalhamento NE-SW, n?o h? correla??o e falhas sismog?nicas normais de dire??o EW est?o ativas e seu movimento ? compat?vel com os esfor?os regionais. ? prov?vel que essas falhas ativas sejam mais recentes que o Neoproteroz?ico, provavelmente do per?odo Cret?ceo, ?poca do ?ltimo grande movimento do Lineamento Pernambuco

At the northern extent of the Cascadia subduction zone, the subducting Explorer and Juan de Fuca plates interact across a translational deformation zone, known as the Nootka fault zone. The Seafloor Earthquake Array Japan-Canada Cascadia Experiment (SeaJade) was designed to study this region. In two parts (SeaJade I and II, deployed from July – September 2010 and January – September 2014), seismic data from the SeaJade project has led to several important discoveries. Hypocenter distributions from SeaJade I and II indicate primary and secondary conjugate faults within the Nootka fault zone. Converted phase analysis and jointly determined seismic tomography with double-difference relocated hypocenters provide evidence to several velocity-contrasting interfaces seaward of the Cascadia subduction front at depths of ~4-6 km, ~6-9 km, ~11-14 km, and ~14-18 km, which have been interpreted as the top of the oceanic crust, upper/lower crust boundary, oceanic Moho, and the base of the highly fractured and seawater/mineral enriched veins within oceanic mantle. During SeaJade II, a MW 6.4 mainshock and subsequent aftershocks, known as the Nootka Sequence, highlighted a previously unidentified fault within the subducted Explorer plate. This fault reflects the geometry of the subducting plate, showing downward bending of the plate toward the northwest. This plate bend can be attributed to negative buoyancy from margin parallel mantle flow induced by intraslab tearing further northwest. Seismic tomography reinforces the conclusions drawn from the Nootka Sequence hypocenter distribution. Earthquakes from the entire SeaJade II catalogue reveal possible rotated paleo-faults, identifying the former extent of the Nootka fault zone from ~3.5 Ma. / Graduate