Dennise C. Templeton

Non-Double-Couple Earthquakes in the Long Valley Volcanic Region

To better understand the connection between earthquake production and geothermal/magmatic systems, we studied the extent of fluid-influenced faulting in the Long Valley volcanic region. We focused on a 100-km-wide circular area centered at the Long Valley caldera that also encompassed the Mono-Inyo craters to the north and the Sierra Nevada mountain block to the south. We performed a comprehensive search for events greater than M 3.5 since 1993 with significant coseismic volume changes in their source region. Using three-component broadband digital waveforms at regional distances, we solved for four different source models: double couple (dc), deviatoric dc + isotropic, and full moment tensor. Using the F -test as a statistical aid, we determined which of the four models was most appropriate for each event. We then conducted stability tests to determine the robustness of the focal mechanism solutions and isotropic components. Our results show that fluid-influenced earthquakes in the magnitude range studied are quite rare in the Long Valley volcanic region. Of 33 high-quality events, 28 are best characterized by a simple dc source model, 4 by a dc + isotropic source model, and 1 by a full moment tensor model.

Partitioning of Seismoacoustic Energy and Estimation of Yield and Height‐of‐Burst/Depth‐of‐Burial for Near‐Surface Explosions

Explosions near the Earths surface excite both seismic ground motions and atmospheric overpressure. The energy transferred to the ground and atmosphere from a near-surface explosion depends on yield (W) as well as the height-of-burst/ depth-of-burial(HOB/DOB)forabove/belowgroundemplacements.Wereportanalyses of seismic and overpressure motions from the Humble Redwood series of low-yield, near-surface chemical explosions with the aim of developing quantitative models of energy partitioning and a methodology to estimate W and HOB/DOB. The effects of yield, HOB, and range on amplitudes can be cast into separable functions of range andHOBscaledbyyield.WefindthatdisplacementoftheinitialPwaveandtheintegral of the positive overpressure (impulse) are diagnostic of W and HOB with minimal scat- ter. An empirical model describing the dependence of seismic and air-blast measure- ments on W, HOB/DOB, and range is determined and model parameters are found by regression. We find seismic amplitudes for explosions of a given yield emplaced at or above the surface are reduced by a factor of 3 relative to fully contained explosions below ground. Air-blast overpressure is reduced more dramatically, with impulse reduced by a factor of 100 for deeply buried explosions relative to surface blasts. Oursignalmodelsare usedtoinvertseismicandoverpressure measurementsforW and HOB and we find good agreement (W errors <30%, HOB within meters) with ground- truth values for four noncircular validation tests. Although there is a trade-off between W and HOB for a single seismic or overpressure measurement, the use of both meas- urement types allows us tolargelybreak this trade-off and better constrainW and HOB. However, both models lack resolution of HOB for aboveground explosions.

Seismic Models for Near‐Surface Explosion Yield Estimation in Alluvium and Sedimentary RockSeismic Models for Near‐Surface Explosion Yield Estimation in Alluvium and Sedimentary Rock

Author(s): Templeton, DC; Rodgers, AJ; Ford, SR; Harben, PE; Ramirez, AL; Foxall, W; Reinke, RE | Abstract: