The Needs forof LowFrequency Seismology Gabi Laske Cecil

The Needs for/of Low-Frequency Seismology Gabi Laske Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics La Jolla IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

Low-Frequency Seismology * what is it good for? * what do we need? * what we usually see * some unexpected encounters * what is broad-band? * outlook IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

What we look at

What is it good for?

Low-Frequency Seismology * what is it good for? * what do we need? * what we usually see * some unexpected encounters * what is broad-band? * outlook IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

What Do We Need? Lots of good seismograms at lots of stations IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

Instrument Responses at New South Pole Station QSPA

What do we need? * observatory quality instruments * high signal-to-noise * several days of continuous data IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

But How Much Data is Fit for Our Studies IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

Category “unload” Seismogram IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

Category “unload” Seismogram, if detected IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

Calibration Signals, A NIGHTMARE! IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

Low-Frequency Seismology * what is it good for? * what do we need? * what we usually see * some unexpected encounters * what is broad-band? * outlook IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

So, What Sensor Suits Us Best? well, of course STS-1/KS 54000. . . or so we think but there is also

What Does This Imply for GSN etc? check all stations systematically! IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

Average Scoring for 20 Greatest EQ of last 10 Years IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

So what does this mean? not sure…. might be that KS 54000 are at noisy sites IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

Noise Spectra at New South Pole Station QSPA STS-1 appears to be quietest 10 m. Hz 1 m. Hz Courtesy Jon Berger/ Kent Anderson

Low-Frequency Seismology * what is it good for? * what do we need? * what we usually see * some unexpected encounters * what is broad-band? * outlook IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

The Three Greatest Earthquakes in 2003

The Three Greatest Earthquakes in 2003 VHZ V: 10 s H: High Gain Z: vertical

Other Stations? Primary Sensor: STS-1 KS 54000/KS 36000 Secondary Sensor: STS-2 CMG 3 B/CMG 3 T

pretty noisy site!

LHZ L: 1 s H: High Gain Z: vertical only 3. 6 h of data at IRIS-DMC!

Quality of Spectra !

Global Seismology Where Do We Go From Here? IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

The Current Global Coverage of Global Seismic Networks

OSN-Ocean Seismic Network (OSN-1 in 98) ION-Integrated Observatory Network (? ? ) interdisciplinary! ORION Workshop, Jan 04 -08, 2004, San Juan, Puerto

Motivation for this Audience * some sensors at GSN near end of lifetime * there are still huge holes in the GSN IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

Low-Frequency Seismology * what is it good for? * what do we need? * what we usually see * some unexpected encounters * what is broad-band? * outlook IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

The Importance of Recording 100 s Rayleigh Waves

Low-Frequency Seismology * what is it good for? * what do we need? * what we usually see * some unexpected encounters * what is broad-band? * a link to shorter periods * outlook IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

Data Logger Problems…. A Thing of the Past? IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

This Is Really Significant to Tomography! IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

Outlook So, What Do We Need? * reliable broad-band sensor (down to 1 m. Hz) (for observatory-quality stations) * low-power/high dynamic range sensor for ocean bottom * reliable data flow to DMC * for temporary deployments: cheap/attractive 120 s sensors (no 40 s sensor) * need to be able to orient horizontal components easily * timing needs to be accurate IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004

Outlook So, What Do We Need? for VHZ! something that works like this … perhaps IRIS Broad-Band Instrumentation Workshop; Lake Tahoe, Mar 24 -26, 2004