Earthquake Seismology Review epicenter S P |Tp-Ts| Tp-Ts = d/(Vp-Vs) hypocenter

Outline Epicenter Locations Magnitude Calculations Focal+Radiation Patterns Epicenter Locations Magnitude Calculations

Outline Epicenter Locations Magnitude Calculations Focal+Radiation Patterns Epicenter Locations Magnitude Calculations

Vertical Displacement Point Source Intensity: u^2 + v^2 P Intensity *Polarity u( u^2 + v^2) S Particle velocity P arrival S arrival Particle velocity

Horizontal Displacement Point Source Intensity: u^2 + v^2 Intensity *Polarity u( u^2 + v^2) P S Particle velocity S arrival P arrival Particle velocity

Horizontal Displacement Point Source Intensity: u^2 + v^2 Intensity *Polarity v( u^2 + v^2) P S Particle velocity S arrival P arrival Particle velocity

Single Couple Point Source Intensity: u^2 + v^2 Intensity *Polarity u( u^2 + v^2) P S Particle velocity S arrival Particle velocity P arrival

Single Couple Point Source Intensity: u^2 + v^2 Intensity *Polarity u( u^2 + v^2) P S Particle velocity S arrival Particle velocity P arrival

Single Couple Point Source Intensity: u^2 + v^2 Intensity *Polarity v( u^2 + v^2) P S Particle velocity S arrival Particle velocity P arrival

S-Wave Radiation Pattern of Earthquakes + - S P Conjugate plane needed to prevent rotation (double couple) ? ? Plan view of S-radiation pattern

Double Couple Point Source Intensity: u^2 + v^2 Intensity *Polarity v( u^2 + v^2) P S Particle velocity S arrival Particle velocity P arrival

Elastic Green’s Function Monopole direction Receiver

Outline Radiation Patterns Eathquakes Epicenter Locations Magnitude Calculations Radiation Patterns Epicenter Locations Magnitude Calculations

Strike Slip Fault Strike Slip No rotation + + - - + - - + + - + P-wave 1st breaks up or down + + - - + - - + + - + Fault Scarp - - - No rotation - - - - - - - - - - - - - - - - - - - - - - + - - - + + - - - + + + - + + Strike Slip - + Auxillary Plane Radiation pattern can’t Distinguish conjugate plane from fault plane

Strike Slip Fault - + - + - - - No rotation Fault Scarp Auxillary Plane - + P-wave 1st breaks up or down - + + - - + Fault Scarp Auxillary Plane No rotation - - + + - - - - - - - + - - - - - - - - - - - - - - - - - - - + - - - + + - - epicenter - + + - + + - + + up motion for P - - + - - hypocenter down motion for P Radiation pattern can’t Distinguish conjugate plane from fault plane

Plotting polarity on projection plane Strike Slip Fault Fault Scarp Auxillary Plane - + Plotting polarity on projection plane gives focal mechanism + -

Stereographic ProjectionStrike Slip Fault Stations around the globe will reveal same focal mechanism pattern as stations just above focus This is an overview of some salient results from our 2003 UTAM research. 1st motion down 1st motion up

Stereographic Projection Shallow Strike Slip Fault Stations around the globe will reveal same focal mechanism pattern as stations just above focus This is an overview of some salient results from our 2003 UTAM research. 1st motion down 1st motion up

Rotated Great Circle Projects as Ellipse This is an overview of some salient results from our 2003 UTAM research.

Rotated Great Circle Projects as Ellipse This is an overview of some salient results from our 2003 UTAM research.

Stereographic Projection Reverse Fault This is an overview of some salient results from our 2003 UTAM research. 1st motion down 1st motion up

Stereographic Projection Normal Fault This is an overview of some salient results from our 2003 UTAM research. 1st motion up 1st motion down

Focal Plane Strike Slip + + - - - - + + + - + - - - - - - - - - - - - P-wave 1st breaks up or down + + - - - - + + + - + - - - - - - - - - - - - - - - - - - - - - - - - - + - - - + + - - - + + + - + + Strike Slip - +

P-Wave Radiation Pattern of Earthquakes Double Couple Event to Prevent Rotation Red indicates positive polarity of 1st P arrival Green indicates negative polarity of 1st P arrival - + S P - - + + + + + - + - + - - Plan view of P-radiation pattern

S-Wave Radiation Pattern of Earthquakes + - S P Conjugate plane needed to prevent rotation (double couple) ? ? Plan view of S-radiation pattern

Double Couple Earthquakes http://rses.anu.edu.au/~nick/teachdoc/lecture11.pdf

Double Couple Earthquakes

Double Couple Earthquakes Thrust Strike slip normal normal

Seismology of Submarine Slumps No confining verical stress, so free to rotate. Single couple earthquake http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V4Y-44JD53M-1&_user=8315259&_coverDate=02%2F28%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1530519978&_rerunOrigin=google&_acct=C000073987&_version=1&_urlVersion=0&_userid=8315259&md5=8690eac3cab9a0dbe964ac6f2a469495&searchtype=a#toc12

Seismology of Submarine Slumps http://www.gps.caltech.edu/uploads/File/People/kanamori/HKjgr87.pdf

Geology of Faulted Earthquakes Rich in shear Keystone block Rich in shear Earthquakes that result from brittle failure are most commonly referred to simply as ordinary "earthquakes."

Seismology of Explosions Explosions are rich in compressional energy. Earthquakes that result from brittle failure are most commonly referred to simply as ordinary "earthquakes."

Seismology of Volcanoes Harmonic tremor describes continuous rhythmic earthquakes that can be detected by seismographs. Harmonic tremors often precede or accompany volcanic eruptions. Fluid dynamic processes driven by pressure and (or) temperature gradients associated with crustal magma may excite seismic waves by a variety of processes including resonances within fluid-filled cracks (Chouet, 1992) and unsteady, nonlinear flow along conduits with irregular geometry (Julian, 1994). The seismic waves generated by such processes typically produce earthquakes deficient in frequencies above 5 to 10 Hz and with extended coda that "ring" for many cycles at a nearly constant frequency (fig. C2). Spectra from seismograms of these earthquakes are typically comb-like with individual peaks showing a harmonic relation to a fundamental mode or a period-doubling relation characteristic of nonlinear systems (Julian, 1994). Such earthquakes are variously referred to as long-period (LP) earthquakes, low-frequency earthquakes, or B-type, volcanic earthquakes (Chouet, 1996; McNutt, 2000). The dominant frequencies for these volcanic earthquakes are typically in the range 1 to 5 Hz. At shallow depths (less than 5 km or 3 miles), LP earthquakes appear to involve the resonance of bubbly fluids in fluid-filled cracks associated with degassing or boiling (Chouet, 1992). At greater depths, non-steady fluid flow may be a more common process (Julian, 1994), although basaltic magmas may behave as a bubbly fluid at pressures typical of mid-crustal depths (10 to 20 km or 6 to 12 miles) with carbon dioxide as the gaseous phase. The deep LP earthquakes beneath Mammoth Mountain that began in late 1989, for example, may be associated with resonances within a basalt-carbon dioxide froth (Pitt and Hill, 1994).

Outline Radiation Patterns Passive Epicenter Locations Magnitude Calculations Radiation Patterns Epicenter Locations Magnitude Calculations

Seismology of Hydrofracs Monitoring well locates events and polarity analysis Identifies type Injection fluid in rock cracks rock Injection fluid in rock explodes rock

Outline Radiation Patterns Epicenter Locations Magnitude Calculations

Epicenter Location of Earthquakes |Tp-Ts | d epicenter S P |Tp-Ts| Tp-Ts = d (Vp-Vs) -1 -1 hypocenter S P S P d=300 km

Outline Radiation Patterns Epicenter Locations Magnitude Calculations

Magnitude of Earthquakes After determining d=300km, you then use magnitude chart to determine strength epicenter Amplitude Amplitude S P 400 300 100 d hypocenter http://www.sciencecourseware.org/eec/Earthquake/

P-Wave Radiation Pattern of Earthquakes Double Couple Event to Prevent Rotation Red indicates positive polarity of 1st P arrival Green indicates negative polarity of 1st P arrival - + S P - - + + + + + - + - + - - Plan view of P-radiation pattern

S-Wave Radiation Pattern of Earthquakes + - S P Conjugate plane needed to prevent rotation (double couple) ? ? Plan view of S-radiation pattern

Double Couple Earthquakes http://rses.anu.edu.au/~nick/teachdoc/lecture11.pdf

Double Couple Earthquakes

Double Couple Earthquakes Thrust Strike slip normal normal

Seismology of Submarine Slumps No confining verical stress, so free to rotate. Single couple earthquake http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V4Y-44JD53M-1&_user=8315259&_coverDate=02%2F28%2F2002&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_searchStrId=1530519978&_rerunOrigin=google&_acct=C000073987&_version=1&_urlVersion=0&_userid=8315259&md5=8690eac3cab9a0dbe964ac6f2a469495&searchtype=a#toc12

Seismology of Submarine Slumps http://www.gps.caltech.edu/uploads/File/People/kanamori/HKjgr87.pdf

1. Radiation Pattern-> Source Mechanism: Summary 1. Radiation Pattern-> Source Mechanism: ? 2. Epicentral Location: Ts-Tp @ 3 or more stations S P S P 3. Magnitude Estimation: Rayleigh Amp.-> Mag. d=300 km