Complex Shear Partitioning Involving the 6 February 2012 MW 6.7 Negros Earthquake Ground Rupture in Central Philippines

Abstract

A 75 km-long, generally NE-striking ground rupture associated with the 6 February 2012 MW 6.7 (Mb 6.9) Negros earthquake was mapped on the eastern side of Negros Island, Philippines. It closely follows a previously unmapped, pre-existing fault trace along the coast which is marked mostly by terrace-forming scarps. The dominance of vertical separation (west side up) is consistent with a west-dipping reverse fault, as indicated by focal mechanism solutions. The ground rupture map eliminates the ambiguity in the focal mechanism solution regarding the orientation, sense of motion, and location of the seismogenic fault plane, which are indispensable in the assessment of seismic hazards and the nature and distribution of deformation. This study uses the ground rupture map of the 2012 Negros earthquake in sorting out the mechanism of deformation in the Visayas Islands region. The ground rupture’s length is well within the aftershock area while its scarp heights are consistent with an earthquake of its magnitude and nature of movement. The 2012 Negros earthquake rupture’s pattern, scarp types, and offset of man-made structures are similar to those of recent reverse/thrust ground ruptures mapped globally and are distinct from those associated with erosion, landslide, and liquefaction. The onshore coseismic reverse fault of the Negros earthquake, which contradicts a model of coseismic slip on an offshore blind thrust fault by previous workers, represents the first thoroughly mapped ground rupture of its kind in the Philippines. The ground ruptures of the 2012 Negros and 2013 Bohol earthquakes, along with the Philippine Trench and the Philippine Fault Zone (PFZ), represent a complex shear partitioning mechanism in the Visayas Islands region. This departs from the current simple shear partitioning model for the region and is distinct from those for other regions along the PFZ and adjacent subduction zones. This study shows how an appreciation of morphotectonic features can lead to a better understanding of the distribution of deformation and the nature of earthquake hazards.

The genus Oligonychus Berlese (Acari, Prostigmata, Tetranychidae): taxonomic assessment and a key to subgenera, species groups, and subgroups

“…In the present study, we observed longitudinal, irregular longitudinal or oblique striae present between both e 1 -e 1 and f 1 -f 1 setae in 10 Oligonychus species of the valid subgenus Reckiella , and longitudinal striae between only e 1 -e 1 setae in a species ( O. andrei Gutierrez) of Reckiella ( Zacher 1921 ; Baker and Pritchard 1960 ; Rimando 1962 ; Meyer 1964 , 1965 , 1974 , 1987 ; Ehara 1966 ; Gutierrez 1966 , 1967 ; Lo and Ho 1989 ; Tseng 1990 ). Furthermore, 13 Oligonychus species of the valid subgenus Reckiella with upturned aedeagus have seven or less than seven tactile setae on tibia I rather than nine setae.…”

“…Thus the setae are named as one pair of clunals and two pair of para-anals, and as a consequence, the statement “one pair of para-anal setae is present in Oligonychus and related genera” appears to be contradictory to what other authors believe. Many authors also mention the presence of h 1 and only one pair of para-anal setae (either h 2 or h 3 ) in the genus diagnosis and descriptions/illustrations of different Oligonychus species ( Rimando 1962 ; Tuttle and Baker 1968 ; Chaudhri et al 1974 ; Meyer 1974 ; Jeppson et al 1975 ; Tuttle et al 1976 ; Zaher et al 1982 ; Tseng 1990 ; Gupta and Gupta 1994 ; Smiley and Baker 1995 ; Ehara 1999 ; Knihinicki and Flechtmann 1999 ; Flechtmann and Etienne 2006 ; Ehara and Gotoh 2007 ; Zeity 2015 , 2016; Alatawi and Kamran 2018 ).…”

Seafloor Structures and Static Stress Changes Associated With Two Recent Earthquakes in Offshore Southern Batangas, Philippines

“…The slow motion in central Philippines induced shortening, particularly in south-central Philippines. This is evidenced by geologic observations (e.g., young anticlines) and recent thrust/reverse faulting events (Aurelio, 2000;Rimando et al, 2019;Rimando et al, 2020). On the other hand, large differences in motion between the blocks create extension zones, such as in the Macolod Corridor.…”

“…Most of the lateral motion is accommodated by the Philippine Fault which spans the entire Philippine archipelago from north to south (Pinet and Stephan, 1990;Ringenbach et al, 1990;Aurelio et al, 1991;Quebral et al, 1996;Tsutsumi and Perez, 2013). However, extensional (Pubellier et al, 1997;Sarewitz and Lewis, 1991;Pubellier et al, 2000) and compressional (Aurelio et al, 2017;Rimando et al, 2019;Rimando et al, 2020) features are also present within the Philippine Mobile Belt, signifying a more complex distribution of shear partitioning (Aurelio 2000;Rimando et al, 2020).…”

An Experimental Approach to Examine the Antecedents of Attitude, Intention, and Loyalty Towards Cause-related Marketing: The Case of India and the Philippines

“…In contrast, researchers argue that Filipino firms aim towards guiding CSR through philanthropic efforts to augment the government’s efforts to address social issues (Habaradas, 2013). Their CSR efforts are motivated by values and heightened religiosity and only a few firms utilize CRM as a model for delivering CSR (Rimando, 2012). Thus, consumers in India may attribute firm centred motives (increasing sales, profits, brand image and legal imperative) to the organizations engaging in CRM in India.…”