Examinando por Autor "Newman, Andrew V."

Mostrando 1 - 4 de 4

Active Deformation near the Nicoya Peninsula, Northwestern Costa Rica, Between 1996 and 2010: Interseismic Megathrust Coupling
(Advancing Earth and Space Sciences, 2012-06-26) Feng, Lujia; Protti, Marino; González, Victor; Jiang, Yan; Dixon, Timothy; Newman, Andrew V.
We use campaign and continuous GPS measurements at 49 sites between 1996 and 2010 to describe the long-term active deformation in and near the Nicoya Peninsula, northwestern Costa Rica. The observed deformation reveals partial partitioning of the Cocos-Caribbean oblique convergence into trench-parallel forearc sliver motion and less oblique thrusting on the subduction interface. The northern Costa Rican forearc translates northwestward as a whole ridge block at 11 1 mm/yr relative to the stable Caribbean. The transition from the forearc to the stable Caribbean occurs in a narrow deforming zone of 16 km wide. Subduction thrust earthquakes take 2/3 of the trench-parallel component of the plate convergence; however, surface deformation caused by interseismic megathrust coupling is primarily trench-normal. Two fully coupled patches, one located offshore Nicoya centered at 15 km depth and the other located inland centered at 24 km depth, are identified in Nicoya with the potential to generate an Mw 7.8 1950-type earthquake. Another fully coupled patch SE of Nicoya coincides with the rupture region of the 1990 Nicoya Gulf earthquake. Interface microearthquakes, non-volcanic tremor, low-frequency earthquakes, and transient slow-slip events generally occur in the intermediately to weakly coupled regions.
Detailed spatiotemporal evolution of microseismicity and repeating earthquakes following the 2012 Mw 7.6 Nicoya earthquake
(Universidad Nacional, Costa Rica., 2017) Yao, Dongdong; Walter, Jacob; Meng, Xiaofeng; Hobbs, Tiegan; Peng, Zhigang; Newman, Andrew V.; Schwartz, Susan Y.; Protti, Marino
We apply a waveform matching technique to obtain a detailed earthquake catalog around therupture zone of the 5 September 2012 moment magnitude 7.6 Nicoya earthquake, with emphasis on itsaftershock sequence. Starting from a preliminary catalog, we relocate ~7900 events using TomoDD to betterquantify their spatiotemporal behavior. Relocated aftershocks are mostly clustered in two groups. Thefirst isimmediately above the major coseismic slip patch, partially overlapping with shallow afterslip. The secondone is 50 km SE to the main shock nucleation point and near the terminus of coseismic rupture, in a zone thatexhibited little resolvable afterslip. Using the relocated events as templates, we scan through the continuousrecording from 29 June 2012 to 30 December 2012, detecting approximately 17 times more than templateevents. Wefind 190 aftershocks in thefirst half hour following the main shock, mostly along the plateinterface. Later events become more scattered in location, showing moderate expansion in both along-trench and downdip directions. From the detected catalog we identify 53 repeating aftershock clusters withmean cross-correlation values larger than 0.9, and indistinguishably intracluster event locations, suggestingslip on the same fault patch. Most repeating clusters occurred within thefirst major aftershock group. Veryfew repeating clusters were found in the aftershock grouping along the southern edge of the Peninsula,which is not associated with substantial afterslip. Our observations suggest that loading from nearby afterslipalong the plate interface drives spatiotemporal evolution of aftershocks just above the main shock rupturepatch, while aftershocks in the SE group are to the SE of the observed updip afterslip and poorly constrained.
Seismogenic zone structure along the Middle America Trench, Nicoya Peninsula, Costa Rica, from 3D local earthquake tomography
(American Geophysical Union, 2004) Deshon, Heather R.; Schwartz, Susan; Dorman, LeRoy; Newman, Andrew V.; Protti, Marino; González, Victor
Resumen de la ponencia "Estructura de la zona sismogénica a lo largo de la Fosa Mesoamericana, Nicoya Península, Costa Rica, a partir de tomografía sísmica local 3D"
Seismogenic zone structure along the middle America trench: results from the Costa Rica seismogenic zone experiment
(IUGG General Assembly, 2003-06-30) Deshon, Heather R.; Schwartz, Susan Y.; Bilek, Susan; Newman, Andrew V.; Dorman, LeRoy; Protti, Marino
Summary of the paper Seismogenic zone structure along the middle america trench: Results fromthe costa rica seismogenic zone experiment