PGS: Veith on Consistent Earthquake Magnitude Estimates

Please join us for the February 15, 2018 meeting of the Potomac Geophysical Society at 7:00 p.m. at the DoubleTree by Hilton McLean Tysons, 1960 Chain Bridge Road, 22102.  This location is within one-half mile of the Tysons Corner Metro station, near I-495, and has free parking available.  Our private meeting room is located in the back of the Orchard Cafe restaurant on the second floor of the hotel.  The optional dinner cost will be discounted to $30 for members in good standing (have paid dues) and students, and $40 for non-members, and is inclusive of iced tea, coffee, tax and gratuity.  Members and guests may attend the presentation after dinner for no charge; we estimate that the presentation will begin at 8:15 p.m.  For attendees who arrive early, social time will be held in O’Malley’s Pub on the first floor of the DoubleTree by Hilton hotel.  Drinks may also be purchased in the private meeting room on a cash basis.

In summary:

Social Time: 6:00-7:00 p.m. O’Malley’s Pub, first floor DoubleTree by Hilton

Dinner: 7:00-8:15 p.m. Orchard Cafe, second floor DoubleTree by Hilton

Meeting & Presentation: 8:15-9:30 p.m. Peachtree Room in the Orchard Cafe, second floor DoubleTree by Hilton

Note: This month we are again offering a special rate of $10 for student dinners when they present their current student ID cards.  We encourage you to attend to network with these students, and to spread the word about our meeting to the students that you work with.  As always, guests are definitely welcomed. We hope to see you there!

This month’s talk and speaker:

Toward Consistent Earthquake Magnitude Estimates – From all Seismic Phases

by Karl F. Veith, PhD, Consultant

Magnitudes were intended to be a measure of seismic event energy. But M b , M s , M L etc. do not necessarily give us the same value for ‘energy’. These magnitude values can vary by as much as 1 – 1.5 mu. To resolve this differential the relative energy levels for the various phases are estimated, relative magnitudes computed and the results compared for both strike-slip and thrust/normal faulting. Amplitude data from the International Seismological Centre bulletins for earthquakes from the western United States, Iran and Europe are analyzed for their relative energy content and the effects of source mechanisms on their ‘magnitude’ estimates for Pg, Lg, Pn, Sn, P, S, P’, and Rayleigh waves. Reliability estimates and the effects of station corrections are also evaluated.

Dr. Veith received a BS and MS in Geophysics from the University of Minnesota and a PhD in Geophysics from Southern Methodist University. He has over fifty years of experience, primarily in the field of arms control verification research.

We hope to see you next Thursday!

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