M.Sc Tezi Görüntüleme

Student:	Serkan ÖZTÜRK
Supervisor:	Asst. Prof. Dr. Yusuf BAYRAK
Department:	Geophysical Engineering
Institution:	Graduate School of Natural and Applied Sciences
University:	Karadeniz Technical University, Turkey

Title of the Thesis:	Statistical Analysis of the Aftershock Sequences of the Earthquakes, Which Recently the Usage of These Variations in Earthquake Risk Assessment
Level:	M.Sc
Acceptance Date:	1/1/1980
Number of Pages:	113
Registration Number:	i1387

Summary:

In this study, by evaluating statistically the space-time magnitude relations for aftershock sequences, which recently occurred in Turkey, of Dinar earthquake of 1 October 1995, Izmit earthquake of 17 August 1999, Duzce earthquake of 12 November 1999, and Sultandagi-Afyon earthquake of 3 February 2002, it is investigated the usage of these variations in the earthquake risk assessment. For this purpose, the data being compiled by The Prosperity and Settling Ministry General Directorate of Disaster Affairs Earthquake Research Department and the catalogs prepared Bogazigi University Kandilli Observatory Research Institute Seismology Laboratory and served to users on the Internet are used.

By plotting the cumulative number of earthquakes as a function of time, the continuity of seismic activity and the time, which there was a drop of the seismicity rate, are tried to determine. Also, by observing the variations of depth and magnitude in time, it is determined in which depth and magnitude aftershock sequences change. It is described

behaviors of cumulative moment against the time, and the b-value of Gutenberg-Richter relation and p-value in the modified Omori law are calculated and thus it is formed spatial variation maps. Cumulative moment variations, Cm,, range from 10* 1023 to 12* 1024 Nm. These variations show that sudden and high increases are accordance with the occurrence of the largest aftershocks. For all aftershock sequences, it is found b-values ranging from 0.5 to 2.2 and p-values ranging from 0.3 to 1.4. In general, the lower and higher values of b and p are found in the same part of the sequences. The lower values are observed in the areas where the largest aftershocks occurred while the higher values are found in the region in which a larger proportion of small events as compared the larger ones are occurred.

Connected with these observations, it is concluded that the site of the lowest b and pvalues have been considered to be the most likely place for a major earthquake and the decrease in the b and p-values may be useful for prediction of large earthquakes.,

Key Words: Magnitude, Aftershock, Cumulative Moment, Omori Law, GutenbergRichter Relation