Faulting Parameters of the January 16, 1994 Wyomissing Hills, Pennsylvania Earthquakes

Other| May 01, 1998 Faulting Parameters of the January 16, 1994 Wyomissing Hills, Pennsylvania Earthquakes Charles J. Ammon; Charles J. Ammon Saint Louis University Earth & Atmospheric Science Dept. 3507 Laclede Ave. Saint Louis, MO 63103 C.J.A. and R.B.H.) Search for other works by this author on: GSW Google Scholar Robert B. Herrmann; Robert B. Herrmann Saint Louis University Earth & Atmospheric Science Dept. 3507 Laclede Ave. Saint Louis, MO 63103 C.J.A. and R.B.H.) Search for other works by this author on: GSW Google Scholar Charles A. Langston; Charles A. Langston Pennsylvania State University Dept. of Geosciences 440 Deike Bldg. University Park, PA 16802 (C.A.L.) Search for other works by this author on: GSW Google Scholar Harley Benz Harley Benz U.S. Geological Survey Box 25046 MS 966 Denver, CO 80225 (H.B.) Search for other works by this author on: GSW Google Scholar Seismological Research Letters (1998) 69 (3): 261–269. https://doi.org/10.1785/gssrl.69.3.261 Article history first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Charles J. Ammon, Robert B. Herrmann, Charles A. Langston, Harley Benz; Faulting Parameters of the January 16, 1994 Wyomissing Hills, Pennsylvania Earthquakes. Seismological Research Letters 1998;; 69 (3): 261–269. doi: https://doi.org/10.1785/gssrl.69.3.261 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySeismological Research Letters Search Advanced Search Abstract Two events dominated the January 1994, Wyomissing, PA earthquake sequence, an Mw 4.0 foreshock, followed by an Mw 4.6 mainshock. We modeled regional waveforms to estimate the event depth and the moment tensors for the two largest events in the sequence, and examine teleseismic waveforms recorded on the ARCESS short-period seismic array to estimate the depth and source time function of the mainshock. Our data constrain the depth of the events to be shallower than 5 km, and prefer a depth of 3–5 km. For an assumed depth of 3 km, the mainshock moment tensor is 75% double couple, with (the major double couple) planes striking at 135°N, 347°N, dips of 49°, 46°, and rakes of 68°, 114°. The estimated moment is 8.9 × 1022 dyne-cm. The P axis strikes 241°N and plunges 2°, the Tension axis strikes 336°N and plunges 73°. The foreshock inversion results are virtually identical to the mainshock results; for a source depth of three km, we find a major double couple with a strike, dip, and rake of 121°N, 60°, and 66°, respectively. The seismic moment for the foreshock is 1.2 × 1022 dyne-cm, which is approximately 13% of the mainshock moment release. These events did not excite high-frequency Lg waves as effectively as typical eastern North American events, and the mainshock had a stress drop in the range of 25–50 bars. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.