Relative source time function studies of earthquakes along the Denali-Totschunda fault system

We use the relative source time function method to estimate the source properties of aftershocks of the November 2002 Denali earthquake sequence to determine if there are systematic variations in scaling relationships of these events that can be related to seismic moment, focal mechanism, event date/time and location along the fault, and bedrock type. Our results show self-similarity over earthquakes of magnitude less than five and stress-drop dependence on focal mechanism. Strikeslip events appear to have larger stress drops.We observed a clear stress-drop decrease from west to east that correlates with changes in earthquake focal mechanisms along the Denali fault. 2013 by the Seismological Society of America

Relative source-time function studies and stress drop of earthquakes in southeastern Alaska-northwestern Canada

We use the relative source-time function (RSTF) method to estimate the source properties of earthquakes within southeastern Alaska-northwestern Canada in an effort to determine if there are systematic variations in the source parameters of these earthquakes (e.g., stress drop, rupture complexity, and rupture directivity) with the tectonic setting. In the RSTF technique we deconvolve the P-arrival signal of a smaller event from that of a larger event by the following process: select arrivals with a tapered cosine window, fast Fourier transform to obtain the spectrum, apply a water level to the spectrum of the smaller event, and apply a band-pass filter before inverse transforming the result to obtain the RSTF. Our results show self-similarity over earthquakes of magnitude less than five and stress drop dependence on focal mechanism. Strike-slip events appear to have larger stress drops, with the highest stress drops for events within the Queen Charlotte fault system. We find evidence for rupture directivity consistent with previous studies for three earthquakes that had adequate azimuthal station coverage

Variability of megathrust earthquakes in the world revealed by the 2011 Tohoku-oki Earthquake

The seismicity of the Pacific coast of Tohoku, Japan has been investigated in detail and characterized into regional seismic segments. The 2011 megathrust earthquake of Mw9.0 on 11 March ruptured almost all of the segments in that area, causing devastating tsunami. The prime factor that had not been recognized before is the double segmentation along the Japan trench: The apparent absence of earthquakes in the trench-ward segments as opposed to the Japan Island-ward segments that have repeated smaller earthquakes. We term this pattern of seismic activity along-dip double segmentation (ADDS). The 2011 Tohoku megathrust is typical of a class of great earthquakes different from that of the 1960 Chile, in which a young and buoyant plate is subducting rapidly under the continental plate. In the 1960 Chile case, the seismic activity is characterized by along-strike single segmentation (ASSS), where there is weak seismic activity before the main event all over the plate interface of the subduction zone. We study the greatest earthquakes around the world and find that there is a variety of megathrust earthquakes characterized by ASSS to ADDS, where the 2004 Sumatra- Andaman, the 1960 Chile, the 1964 Alaska and the 2011 Tohoku-oki earthquakes are typical end-members

Measurement of branching fractions for two-body charmless B decays to charged pions and kaons at BABAR

We present preliminary results of a search for charmless two-body B decays to charged pions and kaons using data collected by the BABAR detector at the Stanford Linear Accelerator Center's PEP-II storage ring. In a sample of 8.8 million produced B-anti-B pairs we measure the branching fractions B(B^0 --> pi^+pi^-) = (9.3^{+2.6}_{-2.3}^{+1.2}_{-1.4}) x 10^{-6} and B(B^0 --> K^+\pi^-) = (12.5^{+3.0}_{-2.6}^{+1.3}_{-1.7}) x 10^{-6}, where the first uncertainty is statistical and the second is systematic. For the decay B^0 --> K^+K^- we find no significant signal and set an upper limit of B(B^0 --> K^+K^-) 6.6 x 10^{-6} at the 90% confidence level

The first year of the BABAR experiment at PEP-II

The BABAR detector, situated at the SLAC PEP-II asymmetric e^+e^- collider, has been recording data at energies on and around the Upsilon(4S) resonance since May 1999. In this paper, we briefly describe the PEP-II B Factory and the BABAR detector. The performance presently achieved by the experiment in the areas of tracking, vertexing, calorimetry and particle identification is reviewed. Analysis concepts that are used in the various papers submitted to this conference are also discussed