New analysis reveals large-scale motion around San Andreas Fault SystemJune 20, 2016
An array of GPS instruments near the San Andreas Fault System in Southern California detects constant motion of Earth's crust--sometimes large, sudden motion during an earthquake and often subtle, creeping motion. By carefully analyzing the data recorded by the EarthScope Plate Boundary Observatory's GPS array researchers from the University of Hawai'i at Mānoa (UHM), University of Washington and Scripps Institution of Oceanography (SIO) discovered nearly 125 mile-wide "lobes" of uplift and subsidence--a few millimeters of motion each year--straddling the fault system. This large scale motion was previously predicted in models but until now had not been documented.
The GPS array records vertical and horizontal motion of Earth's surface. Vertical motion is affected by many factors including tectonic motion of the crust, pumping of groundwater, local surface geology, and precipitation. The challenge faced by Samuel Howell, doctoral candidate at the UHM School of Ocean and Earth Science and Technology (SOEST) and lead author of the study, and co-authors was to discern the broad, regional tectonic motion from the shorter-scale, local motion.
To tease out such motions, the team used a comprehensive statistical technique to extract from the GPS data a pattern of large-scale, smoothly varying vertical motions of the local crust.
"While the San Andreas GPS data has been publicly available for more than a decade, the vertical component of the measurements had largely been ignored in tectonic investigations because of difficulties in interpreting the noisy data. Using this technique, we were able to break down the noisy signals to isolate a simple vertical motion pattern that curiously straddled the San Andreas fault," said Howell.
The pattern resulting from their data analysis was similar in magnitude and direction to motions predicted by previously published earthquake cycle model results led by co-authors Bridget Smith-Konter, associate professor at UHM SOEST, and David Sandwell, professor at SIO.
"We were surprised and thrilled when this statistical method produced a coherent velocity field similar to the one predicted by our physical earthquake cycle models," said Smith-Konter. "The powerful combination of a priori model predictions and a unique analysis of vertical GPS data led us to confirm that the buildup of century-long earthquake cycle forces within the crust are a dominant source of the observed vertical motion signal."
The new findings, published today in Nature Geoscience, indicate that researchers can use GPS vertical motion measurements to better understand the structure and behavior of faults, even in times of earthquake quiescence, when no major ruptures have occurred for several decades to centuries. As scientists patiently monitor the San Andreas Fault System for indications of the next big earthquake, these results will help constrain seismic hazard estimates and may allow for a more prudent mapping of the large-scale motion resulting from the next significant rupture of the San Andreas.
University of Hawaii at Manoa
Related Earthquake Articles:
Scientists reckon with an earthquake with a magnitude of 7 or greater in this region in the coming years.
Researchers at Tohoku University's Department of Geophysics, have been studying the deep earthquake which occurred on May 30, 2015, to the west of Japan's Bonin Islands.
Where a tectonic plate dives under another, in the so-called subduction zones at ocean margins, many strong earthquakes occur.
Preparation and good timing enabled Gareth Funning and a team of researchers to collect a unique data set following the 2014 South Napa earthquake that showed different parts of the fault, sometimes only a few kilometers apart, moved at different speeds and at different times.
The Istanbul metropolitan region faces a high probability for a large earthquake in the near future.
A team of researchers, including one from the University of California, Riverside, has discovered that earthquake ruptures can jump much further than previously thought, a finding that could have severe implications on the Los Angeles area and other regions in the world.
Seismologists at the University of Liverpool studying the 2011 Chile earthquake have discovered a previously undetected earthquake which took place seconds after the initial rupture.
Northwestern University researchers have turned to an unusual source -- Major League Baseball -- to help learn why maps used to predict shaking in future earthquakes often do poorly.
Experts expected for some time that one of the next mega earthquakes occurs off northern Chile.
In the last few months, it has once more become clear that large earthquakes can solicit catastrophic landsliding.
Related Earthquake Reading:
Earthquakes (Let's-Read-and-Find-Out Science 2)
by Dr. Franklyn M. Branley (Author), Megan Lloyd (Illustrator)
Read and find out about one of nature’s most mysterious forces—the earthquake. Some earthquakes are so small that you don’t even feel them, while others can make even big buildings shake! Learn why earthquakes happen, where they are most likely to occur, and what to do if one happens near you.
Now rebranded with a new cover look and with updated text and art, this classic picture book describes the causes and effects of earthquakes (including a tsunami). This book features rich vocabulary and fascinating cross-sections of mountains, volcanoes, and faults in the earth’s moving... View Details
by Seymour Simon (Author)
Seymour Simon knows how to explain science to kids and make it fun. He was a teacher for over twenty years, has written more than 250 books, and has won multiple awards. In Earthquakes, Simon introduces elementary-school readers to earthquakes through engaging descriptions and stunning full-color photographs. He teaches readers why and how earthquakes happen and the damage they can cause through pictures, diagrams, and maps. He also gives real life examples of earthquakes that have occurred all over the world. This book includes a glossary and index.
Supports the Common Core... View Details
Earthquakes (A True Book)
by Ker Than (Author)
A study of earthquakes and the science behind them. View Details
The Great Quake: How the Biggest Earthquake in North America Changed Our Understanding of the Planet
by Henry Fountain (Author)
New York Times Book Review Editors' Choice
In the bestselling tradition of Erik Larson’s Isaac’s Storm, The Great Quake is a riveting narrative about the biggest earthquake in North American recorded history -- the 1964 Alaska earthquake that demolished the city of Valdez and swept away the island village of Chenega -- and the geologist who hunted for clues to explain how and why it took place.
At 5:36 p.m. on March 27, 1964, a magnitude 9.2. earthquake – the second most powerful in world history – struck the young state of Alaska. The... View Details
Earthquake in the Early Morning (Magic Tree House #24) (Magic Tree House (R))
by Mary Pope Osborne (Author), Sal Murdocca (Illustrator)
The #1 bestselling chapter book series of all time celebrates 25 years with new covers and a new, easy-to-use numbering system!
An adventure that will shake you up! That's what Jack and Annie get when the Magic Tree House whisks them back to California in 1906. As soon as they arrive, the famous San Francisco earthquake hits the city. Can Jack and Annie save the day? Or will San Francisco be destroyed first?
Did you know that there’s a Magic Tree House book for every kid?
Magic Tree House: Adventures with Jack and Annie, perfect for readers who are just beginning... View Details
I Survived the San Francisco Earthquake, 1906 (I Survived #5)
by Lauren Tarshis (Author)
The terrifying details of the 1906 San Francisco earthquake jump off the page!
Ten-year-old Leo loves being a newsboy in San Francisco -- not only does he get to make some money to help his family, he's free to explore the amazing, hilly city as it changes and grows with the new century. Horse-drawn carriages share the streets with shiny new automobiles, new businesses and families move in every day from everywhere, and anything seems possible.
But early one spring morning, everything changes. Leo's world is shaken -- literally -- and he finds himself stranded in the middle of... View Details
Quakeland: On the Road to America's Next Devastating Earthquake
by Kathryn Miles (Author)
A journey around the United States in search of the truth about the threat of earthquakes leads to spine-tingling discoveries, unnerving experts, and ultimately the kind of preparations that will actually help guide us through disasters. It’s a road trip full of surprises.
Earthquakes. You need to worry about them only if you’re in San Francisco, right? Wrong. We have been making enormous changes to subterranean America, and Mother Earth, as always, has been making some of her own. . . . The consequences for our real estate, our civil engineering, and our... View Details
Earthquake Terror (Puffin Novel)
by Peg Kehret (Author)
When Jonathan and his family go camping on Magpie Island, they look forward to a fun, relaxing weekend. But their fun quickly vanishes when Jonathan, his sister, Abby, and their dog, Moose, find themselves in the middle of a natural disaster. A devastating earthquake has hit, destroying their camper, knocking out the only bridge to the mainland, and leaving Jonathan, Abby, and their dog with no food, water, or shelter. Alone in the woods, can Jonathan manage to keep calm and save Abby and Moose—and stay alive himself? View Details
Earthquakes: Geology and Weather (Science Readers)
by Teacher Created Materials;William B. Rice (Author)
Most of the Earth's changes happen over millions of years, but earthquakes can force significant changes to the land in just a few moments. Readers will learn the science of plate tectonics and its role in the development of earthquakes around the globe. They will also learn that not all rocks are created equal. In fact, rocks are all different ages! This book concludes with images of the damage and destruction that earthquakes can cause.
About Shell Education
Rachelle Cracchiolo started the company with a friend and fellow teacher. Both were eager to share their ideas and... View Details
Earthquakes: 2006 Centennial Update
by Bruce Bolt (Author)
The ultimate introduction to seismology, written by distinguished scholar and Professor Bruce Bolt, of the University of California, Berkeley, this newly updated edition will provide the best foundation in the field for your introductory students. View Details