 |
|
|
 |
|
 |
| |
Welcome to ProQuest-CSA, your Guide to Discovery. ProQuest-CSA helps researchers worldwide find and manage relevant information in their field. If you're a member of an academic institution you may have access to CSA Illumina. Please contact your library to find out. |
|
 |
|
 |
|
High-precision earthquake location and threedimensional P-wave
velocity determination at Redoubt Volcano, Alaska
Deshon, H | Rowe, C | Thurber, C
100th Anniversary Earthquake Conference. 2006
Redoubt, a stratovolcano located along the Cook Inlet
approximately 166 km from Anchorage, Alaska, most recently erupted
in 1989/1990, and because of its repeated historic eruptions,
routine monitoring with efficient analysis of its behavior is
necessary. The Alaska Volcano Observatory (AVO) has monitored
Redoubt using permanent seismic stations since 1988 and currently
maintains 5 short-period, vertical and 2 short-period,
three-component stations on the volcano. Seismic signals recorded
at Redoubt from 1989-2005 include volcanotectonic, long-period,
and hybrid events, as reflected in the hypocenter catalog reported
by AVO. Over 5000 events have been recorded at Redoubt between
Dec. 1989 and Nov. 2005. Volcano seismic networks typically have
few stations and marginal coverage, providing challenges for
earthquake location in a complex, three-dimensional setting.
Routine catalog locations are performed using analyst phase picks
and an approximate, 1D velocity model. To improve earthquake
location precision at Redoubt, we compute a three-dimensional
P-wave velocity model using double-difference tomography combined
with waveform cross-correlation techniques. Waveforms recorded at
volcanoes are often noisy and/or emergent. We use waveform
cross-correlation techniques to improve the pick accuracy of the
AVO catalog data. Differential travel times for well-constrained
events are used to simultaneously invert for hypocenter location
and P-wave velocity structure. Shot and earthquake arrival times
recorded by temporary stations deployed on Redoubt in July 1991
supplement the catalog picks. The doubledifference tomography
method provides significantly improved absolute and relative
earthquake locations. Synthetic models are used to assess the
accuracy of the resulting 3D model. The 3D velocity model includes
a very high velocity (Vp > 6 km/s) core similar to some other
volcanoes. All Redoubt events through Nov. 2005 are relocated
through the 3D model. We investigate seismicity associated with
the 1989/1990 eruption, and we use cross-correlation results to
identify similar earthquakes within the catalog.
 Descriptors: Seismic phenomena | Catalogs | Waveforms | Volcanoes | Tomography
|
|
|
|
