The Afyon, Turkey Earthquake: Source Characteristics and Implications for Earthquake Triggering
Abstract
Three damaging earthquakes occurred in the Afyon province of southwestern Turkey, in a tectonic complex with triple plate interaction and with adjoining faults. The first occurred on December 15, 2000 (Mw=6.0, named as 001215 hereafter), and the others on February 3, 2002 (Mw=6.5 and Mw=6.0, named as 020203 and 020203a, respectively). The source rupture properties of these earthquakes are investigated using observed faulting (limited data), aftershock distributions, and from inverting broadband seismic data. The fault rupture for event 001215 expanded in a S-E direction for about 30 km. The epicenter of the second event occurred on the first fault, and the rupture propagated NW and continued on a separate E-W fault. The third event was on a NE-SW fault. The source mechanisms and source time functions (STF) of these earthquakes are determined by inverting broadband teleseismic P-waves. A multiple-point source model for event 020203 is also constructed and gives a much better waveform fitting. The results suggest that event 001215 had a relative simple source process. The rupture started at the NW end and unilaterally propagated SE for about 30 km. It lasted about 13 seconds, releasing a total moment of 1.3x1018 Nt-m. Event 020203 had a very complex source process. It can be divided into two steps: First, the rupture initiated from the hypocenter and extended about 15 km in a NW direction along the NW-SE striking fault with oblique left-lateral normal motion. Part of this 15 km fault overlapped the fault zone of event 001215. This step lasted about 10 seconds, releasing a total moment of 9.2x1017 Nt-m. Then, a westward propagating rupture was triggered along an EW striking fault, again with oblique left-lateral normal motion. It lasted more than 15 seconds and had a moment of 3.5x1018 Nt-m, a predominant part of the whole source process. This may explain why other research groups, such as Harvard University, USGS, and Tokyo University gave the focal mechanism solution as an almost pure EW striking fault. Event 020203a happened two hours later and ruptured on a SW trending fault, lasting 6-7 seconds and releasing a moment of 1.2x1018 Nt-m. These events demonstrate a sequential rupturing of three different faults in a tectonically complex area. It is likely that subsequent earthquakes will occur along the SE extension of the initial event.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA....13694K