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Poster Abstracts
rate to about 100 times the long-term rate, and the magnitude 9 event increased it briefly to more than 1000 times the longterm
rate. These results could well justify the development of an operational earthquake forecasting plan.
FULL EARTH HIGH-RESOLUTION EARTHQUAKE FORECASTS (B-124)
Y.Y. Kagan and D.D. Jackson
Since 1977 we have developed statistical short- and long-term earthquake forecasts to predict earthquake rate per unit area,
time, and magnitude. The forecasts are based on smoothed maps of past seismicity and assume spatial and temporal
clustering. Our new program forecasts earthquakes on a 0.1 degree grid for a global region 90N--90S latitude. We use the PDE
catalog that reports many smaller quakes (M>=5.0). For the long-term forecast we test two types of smoothing kernels based
on the power-law and on the spherical Fisher distribution. We employ adaptive kernel smoothing which improves our
forecast both in seismically quiet and active areas. Our forecasts can be tested within a relatively short time period since
smaller events occur with greater frequency. The forecast efficiency can be measured by likelihood scores expressed as the
average probability gains per earthquake compared to spatially or temporally uniform Poisson distribution. The other method
uses the error diagram to display the forecasted point density and the point events.
A GUIDE TO SELECTING EMPIRICAL GREEN’S FUNCTIONS IN REGIONS OF FAULT COMPLEXITY: A
STUDY OF DATA FROM THE SAN JACINTO FAULT ZONE, SOUTHERN CALIFORNIA (B-067)
D.L. Kane, D.L. Kilb, and F.L. Vernon
We examine the appropriateness of applying the empirical Green’s function (EGF) method to constrain the source properties
of target M > 3 mainshock events in regions of complex faulting. A key aspect of our analyses is testing a broad range of trial
EGFs to identify the transition separating appropriate EGF events from other local events that do not satisfy the assumptions
of the EGF method. We use data (>183,000 seismograms from ~56,000 earthquakes) recorded by the ANZA seismic network
(12 seismic stations), which spans the San Jacinto Fault Zone (SJFZ) in southern California. The SJFZ provides a good testing
ground because of its heterogeneous fault structure, high seismicity rate, and diverse distribution of earthquake sources and
locations. We define a M > 3 mainshock catalog of 52 events, and for each mainshock we identify a suite of potential EGF
events that locate within 10 km. For all possible mainshock/EGF pairs, we estimate the preferred corner frequency of the
source spectrum signal that results after spectral division of the EGF spectrum from the mainshock spectrum. We assume that
an ideal EGF choice will result in similar corner frequency estimates at all stations in the array. To quantify this similarity, we
measure the standard deviation of the corner frequency estimates across all stations for each mainshock/EGF pair. Our results
show the preferred EGF events are at least one magnitude unit smaller than the mainshock magnitude. Importantly, we find a
limiting maximum hypocentral separation between the mainshock and EGF of ~2 km (based on a relocated catalog), above
which the results are indistinguishable from pairs with greater separation (e.g., 2-10 km). The EGF event selection can also be
significantly improved by testing for matching first motion polarities and high correlation between the mainshock and EGF
waveforms at each station. Waveform correlation degrades considerably at separation distances greater than 1 km. To select
the most appropriate EGF events, we suggest using only EGF events located within 1 km of the mainshock. However, EGF
events at distances up to 2 km can be considered if one verifies that the mainshock/EGF pair have similar waveforms and
polarities. When sufficient data exists, we suggest applying these pairwise constraints to obtain optimal source parameter
estimates using the EGF method.
INVESTIGATION OF INTERSEISMIC DEFORMATION ALONG THE CENTRAL SECTION OF THE NORTH
ANATOLIAN FAULT (TURKEY) USING INSAR OBSERVATIONS AND EARTHQUAKE-CYCLE
SIMULATIONS (A-051)
Y. Kaneko, Y. Fialko, X. Tong, D.T. Sandwell, and M. Furuya
We present high-resolution measurements of interseismic deformation along the central section of the North Anatolian fault
(NAF) in Turkey using L-band Interferometric Synthetic Aperture Radar (InSAR) data collected by the Advanced Land
Observing Satellite (ALOS) of the Japan Aerospace Exploration Agency. We generated satellite line-of-sight (LOS) velocities
for the three ascending ALOS tracks (603-605) covering the NAF between 31.2-33.2 deg. East. LOS velocity maps for each track
were obtained by averaging 15 to 30 radar interferograms spanning a time period of 4 years between 2007 and 2010. The
average LOS velocities reveal discontinuities of up to ~6 mm/year across the geologically mapped fault trace. Assuming that
these discontinuities are due to horizontal surface motion, they imply fault creep at a rate of ~10 mm/year, accounting for
nearly half of the relative plate motion accommodated by this segment of the NAF. The inferred lateral extent of significant
shallow creep is in excess of 60 km. These inferences are broadly consistent with previously reported trilateration surveys and
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