NSF Org:	EAR Division Of Earth Sciences
Recipient:	THE UNIVERSITY OF TEXAS AT EL PASO
Initial Amendment Date:	August 22, 2011
Latest Amendment Date:	August 22, 2011
Award Number:	1113703
Award Instrument:	Standard Grant
Program Manager:	Eva Zanzerkia EAR  Division Of Earth Sciences GEO  Directorate for Geosciences
Start Date:	September 1, 2011
End Date:	August 31, 2015 (Estimated)
Total Intended Award Amount:	$142,824.00
Total Awarded Amount to Date:	$142,824.00
Funds Obligated to Date:	FY 2011 = $142,824.00
History of Investigator:	Diane Doser (Principal Investigator) doser@utep.edu
Recipient Sponsored Research Office:	University of Texas at El Paso 500 W UNIVERSITY AVE EL PASO TX  US  79968-8900 (915)747-5680
Sponsor Congressional District:	16
Primary Place of Performance:	University of Texas at El Paso 500 W UNIVERSITY AVE EL PASO TX  US  79968-8900
Primary Place of Performance Congressional District:	16
Unique Entity Identifier (UEI):	C1DEGMMKC7W7
Parent UEI:	C1DEGMMKC7W7
NSF Program(s):	Geophysics
Primary Program Source:	01001112DB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s):	1576
Program Element Code(s):	157400
Award Agency Code:	4900
Fund Agency Code:	4900
Assistance Listing Number(s):	47.050

ABSTRACT

Global studies of earthquake source parameters have suggested that high stress drop events are more likely to occur in intraplate regions, along strike-slip faults, and at deeper depths. These studies combine stress drops determined from a variety of methods whose uncertainties are poorly known. The PIs will investigate the validity of these general observations by using a single analysis technique (empirical Green¡¯s function method) on moderate-sized (4.0
The researchers will focus on a preliminary study of earthquakes along the margin of the North Island of New Zealand where the Pacific plate is being subducted (pushed) beneath the island. This margin has large, along-strike variations in geology and structure that affect how parts of the Pacific plate stick or creep as the plate descends. The results will also be relevant to studies of SSE and seismic hazards in other subduction zones such as Cascadia and Alaska. Since many urban regions of the world (e.g. Japan, Cascadia, Indonesia, Chile) are located along these types of plate margins, the results will be useful to scientists who study geologic and tectonic processes at these margins, as well as to improving earthquake hazards models and building codes for these highly urbanized areas. The results of the uncertainty analysis will be useful to researchers studying how similar earthquakes are to one another or how valid it is to use observations from small earthquakes to predict what may happen in larger earthquakes.

PROJECT OUTCOMES REPORT

Disclaimer

This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.

We have studied stress release during earthquakes in New Zealand in an effort to determine if different plate tectonic settings are associated with higher or lower levels of stress release.  New Zealand is an excellent location for this work because there is a high level of seismicity that is well-recorded, and occurring in multiple tectonic settings. The stress released during an earthquake is directly proportional to the ground acceleration, and so higher stress release during an earthquake could lead to greater damage of infrastructures and loss of life.  Unfortunately, stress release is very hard to measure reliably, and results published to date show great variation and little consistency. We studied earthquakes occurring near Wellington within the subducting slab (2004-2005 Upper Hutt and 2014 Ekatahuna sequences) and also in the overlying plate (2013 Cook Strait sequence). During this research we developed a systematic method to analyze earthquake stress release and quantify the uncertainties associated with our analysis methods. Our results to date do not show any significant variation of stress release with geologic setting, earthquake size or earthquake depth; although there is a suggestion that the aftershocks closest to the hypocenter of a main shock release less stress than more distant aftershocks. 

Last Modified: 11/23/2015
Modified by: Diane I Doser

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