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

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.

The Anomaly of ‘Animal’

This chapter uses carters’ strikes led by bullock-cart drivers in late 19th- and early 20th-century Calcutta to explicate the tensions inherent in colonial animal protection legislations. More specifically, it illustrates how a single decisive event – the carters’ strike of 1862 – confronted two parallel and conflicting worlds, that of the poor, uneducated carters and the Calcutta Society for Prevention of Cruelty to Animals (CSPCA). This historic moment is significant not only because it witnessed the meeting of these two worlds, but because by making the animals a mere proxy protagonist, it revealed the complex fault-lines within a colonial society. The human and the nonhuman subalterns – carters and bullocks, found their fates intertwined as the disadvantaged actors in a powerful, but unsuccessful protectionist crusade. Finally, the chapter reveals that while legislations and newer inventions all worked to unburden the overloaded animal, however, in a perfect colonial irony, the meaning of “animal” itself was left vague and amorphous in the British imagination.

ОКАЗИОНАЛИЗМИТЕ В МЕДИЙНИЯ ДИСКУРС ПРЕЗ ПЕРИОДА 2014–2020 Г. – ЕТНОПСИХОЛОГИЧЕСКИ И СЛОВООБРАЗУВАТЕЛНИ АСПЕКТИ / OCCASIONALISMS IN MEDIA DISCOURSE IN THE PERIOD 2014–2020 – ETHNOPSYCHOLOGICAL AND WORD-FORMATION ASPECTS

The study examines occasionalisms excerpted from Bulgarian media texts in the short time span from 2014 to 2020. These newly coined words with strong semantic and emotional intensity are the lexical emanation of Bulgarian ethnopsychology. They represent the linguistic picture of the divided and dichotomised Bulgarian society cha-racterised by egocentricity, ethnoresistance, strive for globalisation, local selfconsciousness, slave complex, fault-finding, imitation of foreign fashions and at the same time – the stigmatisation of everything foreign, among others. The paper analyses occasionalisms as linguistic codes for deciphering the Bulgarian phenotype. They have been grouped according to 11 key ethnopsychological indicators that served as a prerequisite for exploring the participation of occasionalisms in ususbased and nonusus based relations and their connotative dimension, in particular – whether their emotional expressiveness is negative- or positive-evaluative. Further, the author has studied the various word-formation devices occasionalisms employ and has identified both word-formation representations based on familiar linguistic models – ones using a single pattern or a contamination of two or three patterns – and original combinations of two derivational means. Loanwords motivating the formation of occasionalisms have been identified as well. Keywords: media text, Bulgarian phenotype, usus, occasional word-formation, derivational devices, Bulgarian language

Research on Automatic Construction Method of Three-Dimensional Complex Fault Model

Three-dimensional complex fault modeling is an important research topic in three-dimensional geological structure modeling. The automatic construction of complex fault models has research significance and application value for basic geological theories, as well as engineering fields such as geological engineering, resource exploration, and digital mines. Complex fault structures, especially complex fault networks with multilevel branches, still require a large amount of manual participation in the characterization of fault transfer relationships. This paper proposes an automatic construction method for a three-dimensional complex fault model, including the generation and optimization of fault surfaces, automatic determination of the contact relationship between fault surfaces, and recording of the model. This method realizes the automatic construction of a three-dimensional complex fault model, reduces the manual interaction in model construction, improves the automation of fault model construction, and saves manual modeling time.

Complex rupture process of the 2014 Thailand Mw 6.2 earthquake on the conjugate fault system of the Phayao fault zone

The earthquake with a moment magnitude 6.2 that occurred in northern Thailand on 5 May 2014 is the largest recorded in Thailand by modern seismographs; the source is located in the multi-segmented complex fault system of the Phayao fault zone in the northern Thai province of Chiang Rai. This geological setting is appropriate environment for investigating a compound rupture process associated with a geometrically complex fault system in a magnitude-6-class earthquake. To understand in detail the rupture process of the 2014 Thailand earthquake, we elaborate the flexible finite-fault inversion method, used it to invert the globally-observed teleseismic P waveforms, and resolved for the spatiotemporal distribution of both the slip and the fault geometry. The complex rupture process consists of two distinct coseismic slip episodes that evolved along two discontinuous fault planes; these planes coincide with the lineations of the aftershock distribution. The first episode originated at the hypocenter and the rupture propagated south along the north-northeast to south-southwest fault plane. The second episode was triggered at around 5 km north from the epicenter and the rupture propagated along the east-northeast to west-southwest fault plane and terminated at the west end of the source area at 4.5 s hypocentral time. The fault system derived from our finite-fault model suggests geometric complexities including bends. The derived spatiotemporal orientation of the principal stress axis shows different lineations within the two rupture areas and heterogeneity at their edges. This geological setting may have caused the perturbation of the rupture propagation and the triggering of the distinct rupture episodes. Our source model of the 2014 Thailand earthquake suggests that even in the case of small-scale earthquakes, the rupture evolution can be complex when the underlying fault geometry is multiplex.