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A Mw 7.2 earthquake devastated Bohol Island in the Central Philippines region on 15 October 2013 at 8:12 am. The temblor was associated with severe ground rupture, intense ground shaking and other earthquake hazards. Along with numerous landslides and sinkholes that formed during the event, the Bohol earthquake caused 222 deaths and massive destruction to infrastructure amounting to 1.64 million Philippine Pesos (US$38.21 million). The source of the main shock is from an unmapped reverse fault with slight strike-slip component. Ground rupture of the Bohol event is best exposed in Barangay (village) Anonang, Municipality of Inabanga where a fault scarp 3-m high, with mean principal orientation of N51°E is observed. Thousands of inland and offshore aftershocks were recorded, which plots on a general N55°E trend, defining a plane about 100 km long. Using a 1-m resolution digital terrain model (DTM) derived from a Light Detection and Ranging (LiDAR) airborne survey after the earthquake, lineaments were identified and validated through field mapping to define the extent of the inland portion of the earthquake source. Other lineaments within the northern portion of Bohol Island were identified using the Lidar DTM to map out other possible structures in the region that may have been responsible for significantly large aftershocks with strike-slip movement as defined by focal mechanism solutions. Pre-event, 5-m resolution IfSAR DTMs mapped in 2012, were also used to determine changes in morphology after the 2013 temblor, including the identification of older fault scarps in Inabanga, where the newly-formed fault scarp is now seen. Results of this work can be used as reference for future studies to understand the tectonics of Bohol Island and the fatal 15 October 2013 earthquake to mitigate the impacts of future earthquake hazards in the area.
A devastating earthquake struck Bohol, Philip- pines, on 15 October 2013. The earthquake originated at 12 km depth from an unmapped reverse fault, which mani- fested on the surface for several kilometers and with maxi- mum vertical displacement of 3 m. The earthquake resulted in 222 fatalities with damage to infrastructure estimated at USD 52.06 million. Widespread landslides and sinkholes formed in the predominantly limestone region during the earthquake. These remain a significant threat to communi- ties as destabilized hillside slopes, landslide-dammed rivers and incipient sinkholes are still vulnerable to collapse, trig- gered possibly by aftershocks and heavy rains in the upcom- ing months of November and December. The most recent fatal temblor originated from a previously unmapped fault, herein referred to as the Inabanga Fault. Like the hidden or previously unmapped faults responsible for the 2012 Negros and 2013 Bohol earthquakes, there may be more unidentified faults that need to be mapped through field and geophysical methods. This is necessary to mitigate the possible damaging effects of future earthquakes in the Philippines.
Our paleoseismological study of faults and fault-related folds comprising the Mount Narryer fault zone reveals a mid-to late Qua-ternary history of repeated morphogenic earthquakes that have influenced the plan-form and course of the Murchison, Roderick, and Sanford Rivers, Western Australia. The dominant style of deformation involves folding of near-surface sediments overlying discrete basement faults. Carbon-14, optically stimulated luminescence, and in situ–pro-duced 10 Be constrain the timing of the events and late Quaternary slip rates associated with fault propagation folds in tectonically uplifted and deformed alluvial channel deposits. A flight of five inset fluvial terraces is preserved where the Murchison River flows across the Roderick River fault. These terraces, which we infer to be coseismic, are consistent with at least four late Quaternary seismic events on the order of moment magnitude (M w) 7.1 within the last ~240 k.y. Secondary shears expressed on the folds indicate a component of dextral strike-slip displacement. Quaternary slip rates on the underlying faults range from 0.01 to 0.07 mm yr –1 , with a total slip rate for the zone between 0.04 and 0.11 mm yr –1. These rates are intermediate to those in the adjacent Mesozoic basin (>0.1 mm yr –1) and Precam-brian craton (<0.005 mm yr –1) and so provide insight into how tectonic strain is partitioned and transferred across a craton margin.
The SW sector of Mount Natib, a potentially active volcano in the Bataan volcanic arc in western Luzon, is the site of a mothballed nuclear power plant that members of the national legislature have proposed to activate. Detailed geological fieldwork was conducted to assess the capability of the volcano and to identify any volcanic hazards it might pose to the nuclear plant. The nearest eruptive centre is 5.5 km away from the plant. SW Natib Volcano is underlain by lava flows, lahar deposits and at least six pyroclastic density current (PDC) deposits, three directly underlying the nuclear reactor facility. A fault trending N308E is aligned with the Lubao Fault, a capable fault NE of the volcanic edifice. Radon emissions at the traces of these faults are high and comparable to those at known active faults. An associated thrust fault at the nuclear site cuts through lahars up to the ground surface. The results presented here can be used for general hazard preparedness of local communities, and may assist the government to decide whether or not to recommission the nuclear power plant.
The Yakima folds of central Washington, USA, are prominent anticlines that are the primary tectonic features of the backarc of the northern Cascadia subduction zone. What accounts for their topographic expression and how much strain do they accommodate and over what time period? We investigate Manastash anticline, a north vergent fault propagation fold typical of structures in the fold province. From retrodeformation of line-and area-balanced cross sections, the crust has horizontally shortened by 11% (0.8-0.9 km). The fold, and by inference all other folds in the fold province, formed no earlier than 15.6 Ma as they developed on a landscape that was reset to negligible relief following voluminous outpouring of Grande Ronde Basalt. Deformation is accommodated on two fault sets including west-northwest striking frontal thrust faults and shorter north to northeast striking faults. The frontal thrust fault system is active with late Quaternary scarps at the base of the range front. The fault-cored Manastash anticline terminates to the east at the Naneum anticline and fault; activity on the north trending Naneum structures predates emplacement of the Grande Ronde Basalt. The west trending Yakima folds and west striking thrust faults, the shorter north to northeast striking faults, and the Naneum fault together constitute the tectonic structures that accommodate deformation in the low strain rate environment in the backarc of the Cascadia Subduction Zone. Plain Language Summary Viewed from a satellite above Earth, the Yakima folds are west trending, mountain-scale ridges that protrude out of an otherwise flat landscape in central Washington, USA. The problem we address is understanding how the Yakima folds originated. What processes account for their character? Over what time period did the folds form? Are the folds associated with faults that produce earthquakes? To address these questions, we did geologic mapping, we used seismic and gravity surveys, and we investigated high-resolution images. Our results indicate that the folds are underlain by faults, and the faults have been active for the last 15 Ma. The faults are still active and have generated earthquakes within the last 100,00 years. We also propose a framework to understand how the faults and folds in central Washington define the overall tectonic setting of the eastern portion of the Cascadia subduction zone. Our work is important because first, we corroborate the findings of earlier investigators that the Yakima fault-cored folds are seismically active, and second, we put the folding and faulting of the Yakima folds province within a general tectonic model. The model helps inform geologists how Earth's crust is deforming in the Pacific northwest.
Geomorphology
Geomorphology of Active Faulting and seismic hazard assessment: New tools and future challenges2015 •
Journal of Volcanology and Geothermal Research
Geometry and kinematics of the fault systems controlling the unstable flank of Etna volcano (Sicily)2013 •
2011 •
After the very successful 1st Workshop on Earthquake Archaeology and Paleoseismology held in the ancient roman site of Baelo Claudia (Spain, 2009), the INQUA Focus Group on Paleoseismology and Active Tectonics decided to elaborate a bi-annual calendar to support this joint initiative with the IGCP-567 “Earthquake Archaeology”. This second joint meeting moved to the eastern Mediterranean, a tectonically active setting within the Africa-Eurasia collision zone and located in the origins of the pioneer's works on archaeoseismology. ...
Geological Society, London, Special Publications
Geological hazards of SW Natib Volcano, site of the Bataan Nuclear Power Plant, the Philippines2006 •
PATA Proceedings
Paleoseismology of the Western Garlock Fault at Campo Teresa, Tejon Ranch, Southern California2018 •
Zeitschrift der Deutschen Gesellschaft f&# 252; r Geowissenschaften
Active basins and neotectonics: morphotectonics of the Lake Ohrid Basin (FYROM and Albania)2011 •
Zeitschrift der Deutschen Gesellschaft fur Geowissenschaften
Active basins and neotectonics: Morphotectonics of the Lake Ohrid Basin (FYROM and Albania) | Aktive Becken und Neotektonik: Die Morphotektonik des Ohridbeckens (FYROM und Albanien)2011 •
Geo-Marine Letters
Evidence of NW extension of the North Anatolian Fault Zone in the Marmara Sea: a new interpretation of the Marmara Sea (İzmit) earthquake on 17 August 19992001 •
Geo Marine Letters
Evidences of NW extension of the North Anatolian Fault Zone in Marmara Sea; a new approach to the 17th August 1999 Marmara Sea Earthquake2002 •
2010 •
Bulletin of the Seismological Society of America
LiDAR-Assisted Identification of an Active Fault near Truckee, California2011 •
Geological Journal
Seismic catastrophes at the ancient city of Sagalassos (SW Turkey) and their implications for seismotectonics in the Burdur-Isparta area2003 •
Quaternary International
Late Quaternary faulting within the Southern Apennines seismic belt: new data from Mt. Marzano area (Southern Italy)2003 •
Journal of Volcanology and Geothermal Research
Analysis of late Holocene faulting within an active rift using lidar, Taupo Rift, New Zealand2010 •
2013 •
Computers & Geosciences
Tectonic lineament mapping of the Thaumasia Plateau, Mars: Comparing results from photointerpretation and a semi-automatic approach2012 •
International Journal of Earth Sciences
Late Quaternary paleoseismic evidence on the Munébrega half-graben fault (Iberian Range, Spain2009 •
Journal of Seismology
The investigation of potential earthquake sources in peninsular Italy: A review2001 •
Quaternary International
Litho-structural control, morphotectonics, and deep-seated gravitational deformations in the evolution of Alpine relief: A case study in the lower Susa Valley (Italian Western Alps)2007 •
2019 •
Tectonophysics
Active deformation in the eastern Swiss Alps: post-glacial faults, seismicity and surface uplift2004 •
Revista Mexicana de Ciencias Geológicas
The Pastores Fault: Preliminary paleoseismic results and its role in the Acambay graben, Trans-Mexican Volcanic Belt, Mexico
Narod Eco
Rodrigo Narod Eco