Seismological Laboratory Division of Geological and Planetary Sciences



, assistant professor of geophysics, will tap into the fiber network at the Seeley G. Mudd Building of Geophysics and Planetary Science on Caltech's campus on California Boulevard.

ylg娱乐官网Zhan will station two laser emitters that shoot beams of light through the cables. The cables have tiny imperfections every few meters that reflect back a minuscule portion of the light to the source, where it is tracked and recorded. In this manner, each imperfection acts as a trackable waypoint along the fiber optic cable. Seismic waves moving through the ground cause the cable to expand and contract slightly, which changes the travel time of light to and from these waypoints. Thus, the imperfections act like individual seismometers that allow seismologists to observe the motion of seismic waves.

"The City of Pasadena's fiber optics paired with Caltech's research will produce a tremendous amount of data that will help our efforts to prepare, educate, and communicate the impacts of earthquakes in our community," says Phillip Leclair, chief information officer for the City of Pasadena. "Measuring seismic activity with fiber will give officials impact and damage predictions by neighborhood—a huge benefit for public safety and disaster recovery."

"The Pasadena project is an important step forward in lighting up dark fiber throughout Southern California and achieving our vision of a seismic monitoring system equivalent to having a million seismometers placed throughout the region," says , director of Caltech's Seismological Laboratory and John E. and Hazel S. Smits Professor of Geophysics. "This will be a leap forward in our ability to monitor the subsurface in much greater detail. We are particularly grateful for the support shown by the City of Pasadena. This advancement would never have happened without them."

ylg娱乐官网 to read full article by Robert Perkins.

is preparing to launch a project to blanket the Los Angeles Basin with 25 seismic sensors per square mile, gathering high-resolution data at an unprecedentedly wide scale over the 800-square-mile area.

ylg娱乐官网The 3-D passive seismic survey will be a collaboration with seismic exploration company Sisprobe and geophysical consulting firm LA Seismic, and would serve the dual purposes of seismic hazard assessment and identifying areas for improving the resiliency of critical infrastructure.

"The sensors that we use for these surveys were developed for natural resources exploration, but also reveal a great deal about low-level seismicity and seismic hazard," says Clayton, professor of geophysics. "This is an example of how academia can partner with industry to launch large-scale projects."

ylg娱乐官网The end result would be a uniform and detailed ground-motion map revealing the faults beneath the LA Basin, and would be kept in an open-source database.

Clayton has used similar surveys on a smaller scale, blanketing Long Beach, Santa Fe Springs, West Orange County, and South West Los Angeles with thousands of sensors in the past. Those highly localized efforts, conducted over the past eight years, revealed previously undiscovered faults, folds in the earth, and creeping zones.

ylg娱乐官网 to read full article by Robert Perkins.

, assistant professor of geophysics at Caltech and lead author of the Science paper. "It ended up being one of the best-documented earthquake sequences in history and sheds light on how these types of events occur."

The team drew on data gathered by orbiting radar satellites and ground-based seismometers to piece together a picture of an earthquake rupture that is far more complex than found in models of many previous large seismic events.

ylg娱乐官网"We actually see that the magnitude-6.4 quake simultaneously broke faults at right angles to each other, which is surprising because standard models of rock friction view this as unlikely," Ross says. "It is remarkable that we now can resolve this level of detail."

ylg娱乐官网Also noteworthy is that the rupture ended just a few kilometers shy of the nearby Garlock Fault, which stretches more than 300 kilometers across Southern California on the northern boundary of the Mojave Desert. The fault has been relatively quiet for the past 500 years, but the strain placed on the Garlock Fault by July's earthquake activity triggered it to start creeping. Indeed, the fault has slipped two centimeters at the surface since July, the scientists say.

to read full article by Robert Perkins.

). In recognition of his many scientific accomplishments as a young scientist, Zach will receive the prestigious Keiiti Aki Award at the Fall AGU Meeting in San Francisco.

ylg娱乐官网Congratulations Zach!

ylg娱乐官网 for the full list of AGU awadees and named lecturers.

ylg娱乐官网 was held on Saturday, March 16 from 10am - 3pm on Beckman Mall. The event brought the local community and scientists together at Caltech to enjoy, share, and celebrate science.  Seismo Lab students created an interactive earthquake booth which was enjoyed by all who attended.

The booth was manned by Seismo Lab graduate students and post docs, Voon Hui Lai, , Valere Lambert, Celeste Labedz, Xin Wang and Sunny Park.

More photos from the Science for March event.

to apply AI to the big-data problems faced by scientists throughout the Institute. Powered by advanced hardware and machine-learning algorithms, modern AI has the potential to revolutionize seismological data tools and make all of us a little safer from earthquakes. 

Recently, Caltech's , an assistant professor of computing and mathematical sciences, sat down with his collaborators, Research Professor of Geophysics , Postdoctoral Scholar in Geophysics , and Associate Staff Seismologist , to discuss the new project and future of AI and earthquake science. 

ylg娱乐官网 to read the full article written by Elise Cutts.

ylg娱乐官网 . ULVZs can be studied by measuring how they alter the seismic waves that pass through them.

ULVZs are so-named because they significantly slow down the speeds of seismic waves; for example, they slow down shear waves (oscillating seismic waves capable of moving through solid bodies) by as much as 30 percent. ULVZs are several miles thick and can be hundreds of miles across. Several are scattered near the earth's core roughly beneath the Pacific Rim. Others are clustered underneath North America, Europe, and Africa. 

Earth scientists at Caltech now say they know not just what ULVZs are made of, but where they come from. Using experimental methods at high pressures, the researchers, led by Professor of Mineral Physics Jennifer Jackson, have found that ULVZs consist of chunks of a magnesium/iron oxide mineral called magnesiowüstite that could have precipitated out of a magma ocean that is thought to have existed at the base of the mantle millions of years ago. 

Jackson and her colleagues, who reported on their work in a recent paper in the Journal of Geophysical Research: Solid Earth, found evidence supporting the magnesiowüstite theory by studying the mineral's elastic (or seismic) anisotropy; elastic anisotropy is a variation in the speed at which seismic waves pass through a mineral depending on their direction of travel. 

At the pressures and temperatures experienced at the earth's surface, magnesiowüstite exhibits little anisotropy. However, Jackson and her team found that the mineral becomes strongly anisotropic when subjected to pressures comparable to those found in the lower mantle.

Jackson and her colleagues discovered this by placing a single crystal of magnesiowüstite in a diamond anvil cell, which is essentially a tiny chamber located between two diamonds. When the rigid diamonds are compressed against one another, the pressure inside the chamber rises. Jackson and her colleagues then bombarded the sample with x-rays. The interaction of the x-rays with the sample acts as a proxy for how seismic waves will travel through the material. At a pressure of 40 gigapascals—equivalent to the pressure at the lower mantle—magnesiowüstite was significantly more anisotropic than seismic observations of ULVZs.

In order to create objects as large and strongly anisotropic as ULVZs, only a small amount of magnesiowüstite crystals need to be aligned in one specific direction, probably due to the application of pressure from a strong outside force. This could be explained by a subducting slab of the earth's crust pushing its way to the CMB, Jackson says. (Subduction occurs at certain boundaries between earth's tectonic plates, where one plate dives below another, triggering volcanism and earthquakes.)

The study is titled "Strongly Anisotropic Magnesiowüstite in Earth's Lower Mantle." Jackson collaborated with former Caltech postdoctoral researcher Gregory Finkelstein, now at the University of Hawai'i, who was the lead author of this study. This research was funded by the National Science Foundation and the W. M. Keck Institute for Space Studies. 

ylg娱乐官网 to read the full article written by Robert Perkins.

ylg娱乐官网 for the complete list of the 2018 AGU Fellows.

for the list of all 2018 section awardees and named lecturers.

 called NISAR in early 2022 that will provide observations from two directions every 12 days—providing higher-quality, higher-resolution data than have previously been available." With that kind of data, we'll be able to paint an even clearer picture that could reveal even more about the ground beneath our feet," Simons says. 

ylg娱乐官网 to read the full article.