Okada, 1985, Text

Transcription

1 Okada, 19, 1992 Buried dislocation Elastic half-space Relates slip on patch to 3d displacements at surface Differs from seismology where source is infinitesimal Text

2 Strike Slip From Segall, 2

3 Dip Slip From Segall, 2

4 Other Examples Simple - Wells NV, 2 (today) Less Simple - Brawley Swarm, Aug. 212 Complex - El Mayor-Cucapah (Baja), 2 (today) Interesting - Mogul Swarm, Reno, 2 (Steve, Th.) Bizarre - Indian Ocean Event, 211 (Kevin, Th.)

5 Wells, NV Feb M. Bell, 211

6 Large distance to nearest continuous stations small offsets at distant stations (-km) consistent with model for normal faulting (predicted from model obtained from InSAR)

7 GPS Time Series. Difference in position between continuous stations ELKO and GOSH Small displacements become convincing when looking at relative motion before and after event

8 August 2, 212 Brawley Swarm Right step from Imperial to San Andreas Fault Example of low latency GPS results (next day) Processed minute time series and earthquake source parameters from sum of several M+ events e.g. mm offset at P99 Service now available for stations globally Text Figure and results from T. Herring (MIT) Processed next day minute results (G. Blewitt at UNR) more information at:

9 Exit to Matlab for detailed examination Generic earthquake in Walker lane Mogul Swarm Swarms near Coaldale, Hawthorne

10 Horizontal Vectors Longitude V RENO RNO1 STDI Magnitude of Horizontal (mm) Longitude V RENO RNO1 STDI Magnitude of Vertical (mm) Longitude V RENO RNO1 STDI RNO1 RENO STDI Longitude Vertical STEA BOCA 1DOGV

11 3 7 2 Descending Envisat LOS 1 RNO1 1 STDI RENO RNO STDI RENO Longitude Longitude 1 Contribution of Horizontal Contribution of Vertical 7 7 Contribution of Horizontal 7 V V Longitude STDI RENO STDI RENO RNO 2 2 RNO 7 V V Contribution of Vertical Longitude STDI RENO RNO STDI RENO RNO

12 A Few Limitations of earthquake geodesy Not as sensitive as seismometers, hard to see under M with GPS/InSAR (lower threshold for BSMs). Is the world an elastic half-space? Not really. For very large earthquakes need to use spherical Earth model to account for earth curvature. Elastic layering (vertical variation in modulus) Elastic heterogeneity (horizontal variation in modulus) Non-uniqueness of slip estimates from geodetic observations Temporal evolution can be complicated and trade off with other effects (viscoelastic, poroelastic, etc.)

13 Required Elements for Class Talks for GPH 11/11 Project Presentations Dec. 1, 213 Title slide with title, author, affiliation Description of data (type, source, quality) Scientific question addressed (and why is this interesting) Analysis performed Results obtained Conclusions, stating significance

14 Rubric for Class Talks Content (well organized, compelling, logical) Format (title, author, affiliation, data, problem, conclusions) Clarity (can we understand you? are you making sense?) Diction (correct English grammar, intonation) Graphics (relevant, clear, labeled) Presence (eyes, posture, focus)