The Northwest Trending North Boqueron Bay-Punta Montalva Fault Zone; A Through Going Active Fault System in Southwestern Puerto Rico

2013 ◽  
Vol 84 (3) ◽  
pp. 538-550 ◽  
Author(s):  
C. M. Roig-Silva ◽  
E. Asencio ◽  
J. Joyce
Keyword(s):  
Puerto Rico ◽  
Fault Zone ◽  
Active Fault ◽  
Fault System

scholarly journals Morphotectonic Kinematic Indicators along the Vigan-Aggao Fault: The Western Deformation Front of the Philippine Fault Zone in Northern Luzon, the Philippines

Geosciences ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 83 ◽  
Author(s):  
Rolly E. Rimando ◽  
Jeremy M. Rimando
Keyword(s):  
Fault Zone ◽  
Active Fault ◽  
Active Faults ◽  
Vertical Component ◽  
The Philippines ◽  
Google Earth ◽  
Fault System ◽  
Philippine Sea Plate ◽  
Oblique Convergence ◽  
Philippine Fault Zone

The Vigan-Aggao Fault is a 140-km-long complex active fault system consisting of multiple traces in the westernmost part of the Philippine Fault Zone (PFZ) in northern Luzon, the Philippines. In this paper, its traces, segmentation, and oblique left-lateral strike-slip motion are determined from horizontal and vertical displacements measured from over a thousand piercing points pricked from displaced spurs and streams observed from Google Earth Pro satellite images. This work marks the first instance of the extensive use of Google Earth as a tool in mapping and determining the kinematics of active faults. Complete 3D image coverage of a major thoroughgoing active fault system is freely and easily accessible on the Google Earth Pro platform. It provides a great advantage to researchers collecting morphotectonic displacement data, especially where access to aerial photos covering the entire fault system is next to impossible. This tool has not been applied in the past due to apprehensions on the positional measurement accuracy (mainly of the vertical component). The new method outlined in this paper demonstrates the applicability of this tool in the detailed mapping of active fault traces through a neotectonic analysis of fault-zone features. From the sense of motion of the active faults in northern Luzon and of the major bounding faults in central Luzon, the nature of deformation in these regions can be inferred. An understanding of the kinematics is critical in appreciating the distribution and the preferred mode of accommodation of deformation by faulting in central and northern Luzon resulting from oblique convergence of the Sunda Plate and the Philippine Sea Plate. The location, extent, segmentation patterns, and sense of motion of active faults are critical in coming up with reasonable estimates of the hazards involved and identifying areas prone to these hazards. The magnitude of earthquakes is also partly dependent on the type and nature of fault movement. With a proper evaluation of these parameters, earthquake hazards and their effects in different tectonic settings worldwide can be estimated more accurately.

Crustal Architecture of Puerto Rico Using Body-Wave Seismic Tomography and High-Resolution Earthquake Relocation

2021 ◽  
Author(s):  
Guoqing Lin ◽  
Victor A. Huerfano ◽  
Wenyuan Fan
Keyword(s):  
Puerto Rico ◽  
Fault Zone ◽  
Wave Velocity ◽  
Velocity Ratio ◽  
Fault System ◽  
Velocity Models ◽  
Complex Fault ◽  
3D Velocity Model ◽  
Waveform Cross Correlation ◽  
The Caribbean

Abstract Puerto Rico is a highly seismically active island, where several damaging historical earthquakes have occurred and frequent small events persist. It situates at the boundary between the Caribbean and North American plates, featuring a complex fault system. Here, we investigate the seismotectonic crustal structure of the island by interpreting the 3D compressional-wave velocity VP and compressional- to shear-wave velocity ratio VP/VS models and by analyzing the distribution of the relocated earthquakes. The 3D velocity models are obtained by applying the simul2000 tomographic inversion algorithm based on the phase arrivals recorded by the Puerto Rico seismic network. We find high-VP and low-VP/VS anomalies in the eastern and central province between the Great Northern Puerto Rico fault zone and the Great Southern Puerto Rico fault zone, correlating with the Utuado pluton. Further, there are low-VP anomalies beneath both the Great Southern Puerto Rico fault zone and the South Lajas fault, indicating northerly dipping structures from the southwest to the northwest of the island. We relocate 19,095 earthquakes from May 2017 to April 2021 using the new 3D velocity model and waveform cross-correlation data. The relocated seismicity shows trends along the Investigator fault, the Ponce faults, the Guayanilla rift, and the Punta Montalva fault. The majority of the 2019–2021 Southwestern Puerto Rico earthquakes are associated with the Punta Montalva fault. Earthquakes forming 17° northward-dipping structures at various depths possibly manifest continuation of the Muertos trough, along which the Caribbean plate is being subducted beneath the Puerto Rico microplate. Our results show complex fault geometries of a diffuse fault network, suggesting possible subduction process accommodated by faults within a low-velocity zone.

Active displacement on the Calaveras fault zone at Hollister, California

1971 ◽  
Vol 61 (2) ◽  
pp. 399-416
Author(s):  
Thomas H. Rogers ◽  
Robert D. Nason
Keyword(s):  
San Francisco ◽  
Fault Zone ◽  
Active Fault ◽  
San Andreas Fault ◽  
Fault System ◽  
Fault Creep ◽  
San Andreas ◽  
San Andreas Fault System ◽  
Fault Trace ◽  
Fault Displacement

abstract The Calaveras fault zone, which is a major branch of the San Andreas fault system in northern California, passes through the City of Hollister 160 km (100 miles) southeast of San Francisco. Active fault displacement (fault creep slippage) has occurred in and near Hollister along a fault trace within the Calaveras fault zone. Various man-made structures crossing the fault trace have been deformed and gradually offset in a right-lateral sense. The amount of offset varies directly with age of the structure. The maximum offset is 33 cm (13 in) of a sidewalk constructed in the period 1909 to 1914. Offsets on dated structures indicate displacement rates of approximately 2 mm/yr (0.08 in/yr) from 1909 to 1925 and 6 mm/yr (0.24 in/yr) from 1925 to 1967. Data obtained from periodic measurement of specially designed survey lines and instruments have indicated a displacement rate of 9 mm/yr (0.4 in/yr) since May 1967. Displacements of the survey lines are not associated with local earthquake events. Rates of active fault displacement vary with time and position along the Calaveras and San Andreas fault zones in the Hollister area. The pattern of this variation suggests that active displacement on the San Andreas fault zone may be transferring northeastward to the Calaveras fault zone.

scholarly journals Trenching study on the Tonoda Fault of the Mitoke Active Fault System at Sekibayashi, Kyoto Prefecture, Southwest Japan

2000 ◽  
Vol 109 (1) ◽  
pp. 73-86
Author(s):  
Yoshihiro UEMURA ◽  
Atsumasa OKADA ◽  
Heitarou KANEDA ◽  
Daisaku KAWABATA ◽  
Keiji TAKEMURA ◽  
...  
Keyword(s):  
Active Fault ◽  
Fault System ◽  
Southwest Japan

Aftershocks of the February 21, 1973 Point Mugu, California earthquake

1976 ◽  
Vol 66 (6) ◽  
pp. 1931-1952
Author(s):  
Donald J. Stierman ◽  
William L. Ellsworth
Keyword(s):  
Fault Zone ◽  
Main Shock ◽  
Fault Plane ◽  
Body Wave ◽  
P Wave ◽  
Fault System ◽  
Wave Radiation ◽  
Fault Plane Solutions ◽  
Complex Deformation ◽  
Transverse Ranges

abstract The ML 6.0 Point Mugu, California earthquake of February 21, 1973 and its aftershocks occurred within the complex fault system that bounds the southern front of the Transverse Ranges province of southern California. P-wave fault plane solutions for 51 events include reverse, strike slip and normal faulting mechanisms, indicating complex deformation within the 10-km broad fault zone. Hypocenters of 141 aftershocks fail to delineate any single fault plane clearly associated with the main shock rupture. Most aftershocks cluster in a region 5 km in diameter centered 5 km from the main shock hypocenter and well beyond the extent of fault rupture estimated from analysis of body-wave radiation. Strain release within the imbricate fault zone was controlled by slip on preexisting planes of weakness under the influence of a NE-SW compressive stress.

scholarly journals Carbonaceous Materials in the Fault Zone of the Longmenshan Fault Belt: 1. Signatures within the Deep Wenchuan Earthquake Fault Zone and Their Implications

Minerals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 385 ◽  
Author(s):  
Li-Wei Kuo ◽  
Jyh-Rou Huang ◽  
Jiann-Neng Fang ◽  
Jialiang Si ◽  
Haibing Li ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Fault Zone ◽  
Active Fault ◽  
Carbonaceous Materials ◽  
Coseismic Slip ◽  
Earthquake Fault ◽  
Active Fault Zone ◽  
2008 Wenchuan Earthquake ◽  
Seismic Slip ◽  
Longmenshan Fault

Graphitization of carbonaceous materials (CM) has been experimentally demonstrated as potential evidence of seismic slip within a fault gouge. The southern segment of the Longmenshan fault, a CM-rich-gouge fault, accommodated coseismic slip during the 2008 Mw 7.9 Wenchuan earthquake and potentially preserves a record of processes that occurred on the fault during the slip event. Here, we present a multi-technique characterization of CM within the active fault zone of the Longmenshan fault from the Wenchuan earthquake Fault Scientific Drilling-1. By contrast with field observations, graphite is pervasively and only distributed in the gouge zone, while heterogeneously crystallized CM are present in the surrounding breccia. The composite dataset that is presented, which includes the localized graphite layer along the 2008 Wenchuan earthquake principal slip zone, demonstrates that graphite is widely distributed within the active fault zone. The widespread occurrence of graphite, a seismic slip indicator, reveals that surface rupturing events commonly occur along the Longmenshan fault and are characteristic of this tectonically active region.

scholarly journals Latest Rupture Event of the Mino Fault, the Median Tectonic Line Active Fault System, in East Shikoku, Southwest Japan.

2002 ◽  
Vol 111 (5) ◽  
pp. 661-683 ◽  
Author(s):  
Michio MORINO ◽  
Atsumasa OKADA ◽  
Takashi NAKATA ◽  
Koji MATSUNAMI ◽  
Masayoshi KUSAKA ◽  
...  
Keyword(s):  
Active Fault ◽  
Fault System ◽  
Southwest Japan ◽  
Median Tectonic Line ◽  
Tectonic Line
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