Primjena združenih metoda refrakcijske i refleksijske seizmičke tomografije u području subdukcijske zone Kolumbija-Ekvador

master's thesis

• Title (english): Application of joint refraction and reflection travel time seismic tomography in the area of Colombia-Ecuador zone
• Author: Domagoj Terzić
• Mentor: Snježana Markušić (mentor)
• Committee member: Snježana Markušić (predsjednik povjerenstva)
• Committee member: Davorka Herak (član povjerenstva)
• Committee member: Maja Telišman Prtenjak (član povjerenstva)
• Committee member: Ivica Sović (član povjerenstva)
• Committee member: Željko Večenaj (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Geophysics); Zagreb
• Defense date and country: 2018-10-18, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Geophysics; Seismology and Physics of the Earth's Interior

Abstract

Esmeraldas projekt je 3D seizmičko istraživanje iz 2005. godine u području subdukcijske zone blizu granice Kolumbije i Ekvadora koje obuhvaća veći dio područja loma potresa iz 1958. te dijelove većih potresa u zadnjih 120 godina. Geometrija istraživanja postavljena je tako da se uz nailaske refraktiranih valova mogu odrediti nailasci za one reflektirane valove čiji je upadni kut približan ili veći graničnom kutu. Podatke istraživanja prvo su iskoristili García-Cano i sur. [2014] za odredivanje 3D modela brzina P-valova koristeći vremena putovanja refraktiranih valova. Meléndez [2014] je iskoristio podatke od García-Cano i sur. [2014] da testira svoj tomografski program TOMO3D. U ovom radu refrakcijski podaci prethodnih radova korigirani su, te je koristeći TOMO3D program dobiven 3D model brzina P-valova s boljim statističkim rezultatima od prethodnih radova. Zatim su dodana refleksijska vremena putovanja kako bi se testirala združena inverzija programa TOMO3D i odredila geometrija diskontinuiteta na vrhu subducirane litosfere. Dobiveno je poboljšanje modela brzina, dok određena geometrija diskontinuiteta nije zadovoljavajuća. Ipak, položaj diskontinuiteta dovoljno je dobar da se analiziraju brzine iznad njega te da se na taj način provjeri valjanost pretpostavke konstantnog modula smicanja pri određivanju seizmičkog momenta potresa u subdukcijskim zonama. Otkriveno je da postoje znatne lateralne varijacije brzine, što može značiti i velike varijacije modula smicanja.

Abstract (english)

Esmeraldas project is a 3D refraction and wide-angle reflection seismic experiment from 2005 which was conducted in the subduction zone at the border between Ecuador and Colombia. Area of the experiment covers large part of the 1958 earthquake rupture zone and parts of the other large earthquakes in the last 120 years. García-Cano et al. [2014] obtained 3D P-wave velocity model using refraction data from the experiment. Meléndez [2014] used their data to test his tomography code TOMO3D. In this paper refraction data from previous studies were corrected and using TOMO3D 3D P-wave velocity model was obtained with better statistical results than the previous works. Next step was to include the reflection data to test the TOMO3D joint tomography and to obtain reflector geometry. The velocity model was improved, but the final reflector geometry wasn’t satisfactory. The position of the reflector was still good enough to analyze velocities above it and to check the validity of taking constant rigidity value in the process of earthquake seismic momment calculations. Lateral velocity variations do exist and they are big enough that we can talk about possibility of significant lateral variations of rigidity.

• Keywords: subdukcijske zone; združena refrakcijska i refleksijska tomografija; modul smicanja
• Keywords (english): subduction zones; joint refraction and reflection tomography; rigidity
• Language: croatian
• URN:NBN: urn:nbn:hr:217:445660
• Study programme: Title: Graduate university study pf Physics - Geophysics; specializations in: Seismology and Physics of the Earth's Interior, Meteorology and Physical Oceanography; Course: Seismology and Physics of the Earth's Interior; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra fizike – geofizike (magistar/magistra fizike – geofizike)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-11-05 09:16:55