| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
U.S. Geological Survey ms977, Menlo Park, California 94025
Carnegie Inst. of Washington Dept. Terrestrial Magnetism, Washington, D.C. 20015
CIRES University of Colorado, Boulder, Colorado 80309-0250
Abstract
Continuous records from a borehole strainmeter and a long baseline tiltmeter in the Long Valley caldera provide critical insights into the origin of at least one episode of minor seismicity in volcanic regions triggered by the 28 June 1992, ML 7.3 Landers, California, earthquake. A strain transient reaching a peak of 0.25 microstrain occurred in the few days following the Landers event and decayed over the next 20 days. A tilt perturbation during the same time reached a peak amplitude of 0.2 microradians. These signals correspond approximately in time to the primary seismic moment release across a 50 km2 region of the south part of the caldera at depths between 2 and 10 km. Corresponding strain transients in 5-km geodetic lines across the south caldera are not apparent above the 95% confidence limits of about 0.4 microstrain in daily sampled data during this same period. These data rule out models involving single localized inflation sources within the upper crust beneath the caldera, including that responsible for the current rapid inflation of the resurgent dome. They also preclude models involving aseismic slip on single strike-slip or normal faults in the caldera. A single source in the form of a relaxing magma body at a depth of 50 km beneath the caldera can account for the deformation data, but whether the small stress changes are sufficient to drive the triggered seismicity is not clear. An alternate possibility involves distributed deformational sources triggered by the passage of the 10 microstrain peak amplitude surface waves from the earthquake. This distributed deformational source could result either from rupturing of overpressured fluid or gas chambers commonly encountered in volcanic regions or from advective gas overpressure during release of gas bubbles in hydrothermal or magmatic fluids.
This article has been cited by other articles:
|
|
 |
|
  S. Husen, S. Wiemer, and R. B. Smith Remotely Triggered Seismicity in the Yellowstone National Park Region by the 2002 Mw 7.9 Denali Fault Earthquake, Alaska Bulletin of the Seismological Society of America, December 1, 2004; 94(6B): S317 - S331. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. J. S. Johnston, S. G. Prejean, and D. P. Hill Triggered Deformation and Seismic Activity under Mammoth Mountain in Long Valley Caldera by the 3 November 2002 Mw 7.9 Denali Fault Earthquake Bulletin of the Seismological Society of America, December 1, 2004; 94(6B): S360 - S369. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Changes in geyser eruption behavior and remotely triggered seismicity in Yellowstone National Park produced by the 2002 M 7.9 Denali fault earthquake, Alaska Geology, June 1, 2004; 32(6): 537 - 540.
|
|
|
|
|
|
The Athens, Greece, Earthquake (Ms 5.9) of 7 September 1999: An Event Triggered by the Izmit, Turkey, 17 August 1999 Earthquake? Bulletin of the Seismological Society of America, February 1, 2002; 92(1): 312 - 321.
|
|
|
|
|
|
Seismic Response of the Katmai Volcanoes to the 6 December 1999 Magnitude 7.0 Karluk Lake Earthquake, Alaska Bulletin of the Seismological Society of America, February 1, 2001; 91(1): 57 - 63.
|
|
|
|
|
|
C. Lomnitz Search of a worldwide catalog for earthquakes triggered at intermediate distances Bulletin of the Seismological Society of America, April 1, 1996; 86(2): 293 - 298. [Abstract] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
