We present here a new InSAR persistent scatterer (PS) method for analyzing episodic crustal deformation in non‐urban environments, with application to volcanic settings. Our identifying PS pixels series of interferograms is based primarily on phase characteristics and finds low‐amplitude stability that are not identified by the existing amplitude‐based algorithm. also uses spatial correlation phases rather than well‐defined history so we can observe temporally‐variable processes, e.g.,...

Fault traces consist of numerous discrete segments, commonly arranged as echelon arrays. In some cases, discontinuities influence the distribution slip and seismicity along faults. To analyze fault we derive a two‐dimensional solution for any number nonintersecting cracks arbitrarily located in homogeneous elastic material. The includes interaction between cracks. Crack surfaces are assumed to stick or according linear friction law. For an array ratio maximum length significantly...

While conventional interferometric synthetic aperture radar (InSAR) is a very effective technique for measuring crustal deformation, almost any interferogram includes large areas where the signals decorrelate and no measurement possible. Persistent scatterer (PS) InSAR overcomes decorrelation problem by identifying resolution elements whose echo dominated single in series of interferograms. Existing PS methods have been successful analysis urban areas, stable angular structures produce...

Research Article| October 01, 1989 Earthquakes triggered by fluid extraction P. Segall 1U.S. Geological Survey, Menlo Park, California 940252Department of Geophysics, Stanford University, Stanford, 94305-2215 Search for other works this author on: GSW Google Scholar Author and Article Information Publisher: Society America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print 0091-7613 Geology (1989) 17 (10): 942–946. https://doi.org/10.1130/0091-7613(1989)017<0942:ETBFE>2.3.CO;2 history...

We analyze the conditions for unstable slip of a fluid infiltrated fault using rate and state dependent friction model including effects dilatancy pore compaction. postulate existence steady drained porosity gouge which depends on velocity as ϕ ss = 0 + εln( v / ) over range considered, where is sliding ε are constants. Porosity evolves toward same distance scale, d c , “state.” This constitutive predicts changes in upon step that consistent with experiments Marone et al. (1990). For...

Abstract The standard model of injection‐induced seismicity considers changes in Coulomb strength due solely to pore pressure. We consider two additional effects: full poroelastic coupling stress and pressure, time‐dependent earthquake nucleation. pressure specified injection rate a homogeneous, medium. Stress are used compute through the Dieterich (1994) model. For constant rate, time reach critical scales with t ∼ r 2 /( c f ), where is distance from injector, hydraulic diffusivity, factor...

Fractures within granodiorite of the central Sierra Nevada, California, were studied to elucidate mechanics faulting in crystalline rocks, with emphasis on nucleation new fault surfaces and their subsequent propagation growth. Within study area fractures form a single, subparallel array which strikes N50°–70°E dips steeply south. Some these are identified as joints because displacements across fracture exhibit dilation but no slip. The filled undeformed minerals, including epidote chlorite....

Research Article| December 01, 1982 Formation and interpretation of dilatant echelon cracks DAVID D. POLLARD; POLLARD 1U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar PAUL SEGALL; SEGALL T. DELANEY 2U.S. Flagstaff, Arizona 86001 GSA Bulletin (1982) 93 (12): 1291–1303. https://doi.org/10.1130/0016-7606(1982)93<1291:FAIODE>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Manager Share Icon MailTo...

The mechanics of slow slip events (SSE) in subduction zones remain unresolved. We suggest that SSE nucleate areas unstable friction under drained conditions, but as accelerates dilatancy reduces pore pressure p quenching instability. Competition between dilatant strengthening and thermal pressurization may control whether is or fast. model with 2‐D elasticity, rate‐state friction, a law where porosity evolves toward steady state ss over distance d c = 0 + ln( v / ); speed. consider two...

Earthquakes have been induced by oil and gas production, where pore pressures decreased, in some cases several tens of MPa. It has previously suggested that such earthquakes are caused poroelastic stressing crust surrounding the reservoir. Induced also common geothermal fields, as The Geysers, strong correlations between both steam production condensate injection, earthquake activity observed over last decades. Stress measurements within hydrocarbon reservoirs show least horizontal stress...

Research Article| May 01, 1983 Joint formation in granitic rock of the Sierra Nevada PAUL SEGALL; SEGALL 1U.S. Geological Survey, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar DAVID D. POLLARD GSA Bulletin (1983) 94 (5): 563–575. https://doi.org/10.1130/0016-7606(1983)94<563:JFIGRO>2.0.CO;2 Article history first online: 01 Jun 2017 Cite View This Citation Add to Manager Share Icon Facebook Twitter LinkedIn MailTo Tools Get Permissions Site SEGALL,...

The Parkfield, California, segment of the San Andreas fault is transitional in character between creeping to northwest and locked Carrizo Plain southeast. rate shallow slip decreases from 25–30 mm/yr epicenter 1966 Parkfield earthquake zero at southeastern end rupture zone. Data a network trilateration lines spanning near extending Pacific coast Luis Obispo shed light on depth since earthquake. In this study, average rates line length change were inverted determine segment. taken be vertical...

Abstract Most significant induced earthquakes occur on faults within the basement beneath sedimentary cover. In this two‐dimensional plane strain numerical study, we examine full poroelastic response of to fluid injection into overlying strata, considering both (1) permeability fault zone and (2) hydraulic connectivity target horizon. Given mechanical properties, compute spatiotemporal change in Coulomb stress, which separate stresses Δ τ s + f σ n , where are changes shear normal stress (Δ...

Caldera collapse and flank eruption Real-time monitoring of volcanic eruptions involving caldera-forming events are rare (see the Perspective by Sigmundsson). Anderson et al. used several types geophysical observations to track at top Kīlauea Volcano, Hawai'i, during 2018 eruption. Gansecki near–real-time lava composition analysis determine when magma shifted from highly viscous, slow-moving low-viscosity, fast-moving lava. Patrick a range tools connect processes summit rates coming out...

Abstract Foreshocks are not uncommon prior to large earthquakes, but their physical mechanism remains controversial. Two interpretations have been advanced: (1) foreshocks driven by aseismic nucleation and (2) cascades, with each event triggered earlier ones. Here, we study seismic cycles on faults fractal roughness at wavelengths exceeding the length. We perform 2‐D quasi‐dynamic, elastic simulations of frictionally uniform rate‐state faults. Roughness leads a range slip behavior between...

Hundreds of shallow, small to moderate earthquakes have occurred near the Lacq deep gas field in southwestern France since 1969. These are clearly separated from tectonic seismicity occurring Pyrenees, 25 km southwest. The induced began when reservoir pressure had declined by ∼30 MPa. Repeated leveling over shows localized subsidence reaching a maximum 60 mm 1989. Segall (1989) suggested that poroelastic stressing, associated with volumetric contraction rocks, is responsible for fluid...

▪ Abstract Geodetic measurements obtained with the Global Positioning System (GPS) are increasingly more widely applied in geophysical studies. In this paper, we review changes to technology of GPS geodesy over last five years that responsible for increased applicability. We survey investigations employing measure coseismic, postseismic, and interseismic deformation; plate motion crustal deformation at boundaries; volcano associated glacial isostatic adjustment its application sea-level...

GPS time series following the September 25, 2003 (UT) Tokachi‐oki earthquake ( M W ∼ 8.0) reveal significant deformation. We use Network Inversion Filter to invert for spatial and temporal evolution of afterslip in 30 days earthquake. Afterslip is concentrated adjacent coseismic rupture zone, between inferred source regions 1968 1973 Nemuro‐oki earthquakes. The inversion shows a rapid decay slip‐rate with slower deceleration surrounding regions. stress‐velocity paths approximately follow d...

Research Article| September 01, 1988 Development of simple strike-slip fault zones, Mount Abbot quadrangle, Sierra Nevada, California STEPHEN J. MARTEL; MARTEL 1Department Applied Earth Sciences, Stanford University, Stanford, 94305 Search for other works by this author on: GSW Google Scholar DAVID D. POLLARD; POLLARD 2Departments Sciences and Geology, PAUL SEGALL 3U.S. Geological Survey, 345 Middlefield Road Menlo Park, 94025 GSA Bulletin (1988) 100 (9): 1451–1465....

Research Article| January 01, 1986 Nucleation of ductile shear zones on dilatant fractures Paul Segall; Segall 1U.S. Geological Survey, 345 Middlefield Road, MS 977, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Carol Simpson 2Department Sciences, Virginia Polytechnic Institute and State University, Blacksburg, 24061 Author Article Information Publisher: Society America First Online: 01 Jun 2017 Online ISSN: 1943-2682 Print 0091-7613 Geology (1986)...