Saturday, April 25, 2015

Accumulating a few links on the April 25, 2015 M7.9 Nepal Earthquake

An M7.8 earthquake occurred 77km (48mi) NW of Kathmandu, Nepal April 25, 2015. It apparently occurred along the Main Himalayan thrust fault system which accommodates the substantial convergence between India and Eurasia. The last great earthquake in this region along the Himalayan arc was about 240 km southeast--the 1934 M8 1934 Nepal-Bihar earthquake--and caused major damage to Kathmandu and about 10,600 casualties. This 2015 earthquake is likely to have been devastating. More than 3.6 million people are expected to have felt very strong shaking.

May 12, 2015: a large aftershock occurred on the eastern end of the April 25, 2015 rupture zone: USGS summary

See this Jonathan Amos/BBC explainer on Why Nepal is so vulnerable to quakes. And, here is a blog entry from NY Times on Himalayan seismic risk. Here is the anticipation of damage and casualties from USGS Pager.

The focal mechanism, inverted finite fault, and the aftershocks are consistent with the interpretation of the event along the Himalayan Thrust system.

Here are some links I am accumulating:

Wednesday, March 4, 2015

New papers on earliest Homo from our Ethiopia collaboration

We have two papers coming out in Science on our research in the Afar, Ethiopia which document early Homo (based on a high quality mandible and teeth) at 2.8 Ma--about 400kyr earlier than the last reported example (from Hadar--Kimbel, et al., 1996). Our work over numerous field seasons since 2002 was to build on the very little prior information to produce a structural and stratigraphic and temporal framework into which we could place any fossils of importance. The area is faulted (due to regional extension pulling the Horn of Africa away to the east and Arabia away to the northeast from the rest of Africa) so we have to divide it into separate fault blocks and characterize each individually and then relate them temporally both by the basic logic of geology as well as by numerical and correlative dating of numerous volcanic deposits (“tephra”). The important point is that the sedimentary sequence represents a time period previously undocumented in the region (hence the opportunity of finding and documenting this mandible).

Here is the ASU press release.

Both papers have ASU alumns as first authors:

Early Homo at 2.8 Ma from Ledi-Geraru, Afar, Ethiopia
Brian Villmoare, William H. Kimbel, Chalachew Seyoum, Christopher J. Campisano, Erin DiMaggio, John Rowan, David R. Braun, J. Ramon Arrowsmith, and Kaye E. Reed
Published online 4 March 2015 [DOI:10.1126/science.aaa1343] 
Late Pliocene fossiliferous sedimentary record and the environmental context of early Homo from Afar, Ethiopia
Erin N. DiMaggio, Christopher J. Campisano, John Rowan, Guillaume Dupont-Nivet, Alan L. Deino, Faysal Bibi, Margaret E. Lewis, Antoine Souron, Lars Werdelin, Kaye E. Reed, and J. Ramón Arrowsmith
Published online 4 March 2015 [DOI:10.1126/science.aaa1415] 

This research is very much interdisciplinary: our international team (graduate students to senior researchers) includes expertise ranging from evolution of dental anatomy to geologists (stratigraphy, dating, structures) to paleontology and ecology. This great breadth is required to produce, integrate, and interpret the complex and often subtle story of hominin evolution. We have worked to build a space and time constrained paleoenvironmental framework in which to consider the hominin. The core team spans the Arizona State University campus in the Schools of Human Evolution and Social Change/Institute of Human Origins and the School of Earth and Space Exploration.

The geological work was part of Erin DiMaggio's Ph.D. dissertation. She worked with me on her M.S. and Ph.D., finishing the latter in 2013. This work is part of a sustained collaboration with friends and colleagues from whom I have learned very much (Kaye Reed, Chris Campisano, Bill Kimbel, Brian Villmoare, and Guillaume Dupont-Nivet to name a few). We also started the work with our friend Charles Lockwood who sadly passed away several years ago. He would have been really happy about this.

Here are a few other links:

Here is an old page with maps
Here are many pictures from over the years:
Ethiopia and Afar region (2002)
Ethiopia and Afar region (2004)
Ethiopia and Afar region (2005)
Ethiopia and Afar region (2006)
Ethiopia and Afar region (May 2008)
Web-sized images for Ethiopia and Afar region (November 2008); Ethiopia and Afar region (November 2008) full size images
Web-sized images for Hadar Field School (2009); Hadar Field School full size images
Afar region 2012
Afar region 2013
Afar region 2015

This research was funded by the NSF (BCS-1157351 and BCS-1322017), the Institute of Human Origins and School of Human Evolution and Social Change at ASU, grants to E.N.D. from AAPG, SEPM, GSA, and the Philanthropic Education Organization, to G.D-N. from Marie Curie CIG and A. v. Humboldt, and to A.S. from Fyssen and HERC/UC Berkeley.

Saturday, January 10, 2015

Hominin Sites and Paleolakes Drilling Project - HSPDP team meeting at Biosphere 2 Jan 9-10, 2015

We had a very interesting and stimulating meeting of the Hominin Sites and Paleolakes Drilling Project - HSPDP team at the Biosphere2 January 9 and 10, 2015. It was fun to see everyone and the venue was really great. Thanks to our hosts!

Watching the 3D movie (thanks Doug Prose)

Touring the Biosphere2 was really cool! Very impressive facility!

Friday, January 2, 2015

AGU 2014 and EarthScope Town Hall

The American Geophysical Union Fall 2014 meeting came and went. It is quite a taxing meeting. But, I saw some old friends and many colleagues. A highlight was running the EarthScope Town Hall. Our agenda was:

  • EarthScope overview, science achievements, and status (Arrowsmith)
  • Update from the National Science Foundation (Benoit)
  • Plate Boundary Observatory Futures workshop report (James Foster)
  • IRIS Science workshop report and Transportable Array update (Central Eastern US network and Alaska deployments; Bob Detrick)
  • Upcoming meetings overview (Arrowsmith)
  • Questions and discussion
Here is a copy of my talk (includes the presentations of Foster and Detrick): ppt and pdf. We did not get a lot of discussion but there were about 70 people in attendance and it seemed as if it were useful.

We also had our EarthScope Booth which was very well managed by our team (Cindy Dick, Sarah Robinson, and guest booth host Jeff Lockridge). Thanks to them for their hard work and all who stopped by. Steve Semken and I were running around with busy schedules but we enjoyed our EarthScope interactions. We also had a couple of EarthScope Education and Outreach posters lead by Sarah Robinson, Steve Semken, Wendy Bohon, and Kathy Ellins.

Monday, December 1, 2014

November 30, 2014 M4.7 earthquake between Sedona and Flagstaff

Last night, a M4.7 earthquake occurred between Flagstaff and Sedona (just west of Munds Park). I hope it was not too scary for my friends and colleagues. It sounds like it got their attention! I agree with Professor Brumbaugh from NAU who said: "It was a large enough earthquake to be felt, but not quite large enough to really get too concerned about" (link).

Arizona Geological Survey colleagues (some ASU alumns!) are responding. Here is a blog entry from Arizona Geology on the event. Here is a nice map from them with better locations:

The USGS shakemap indicates that light shaking is reported from north Phoenix to north of Flagstaff. If you know someone who felt it; tell them to go to that site and record their perceptions.

Here is the seismogram from Tucson:

and if you go to the IRIS page on the eventyou can hear it!

The earthquake occurred in an area where there are some active faults, most notably the Lake Mary fault system south of Flagstaff. Here is the epicenter on a map of USGS Quaternary Active Faults:

Here it is with historic seismicity (from Jeff Lockridge). There was an M3.5 within a few km of this event on November 25, 2014.
Here is the epicenter on the Geologic Map of Arizona:
The epicenter is right on top of the Oak Creek Fault. So it could be associated with that fault, but it would need to be located further east given the eastward dip of the Oak Creek fault. I see that the focal mechanism is available now from the USGS and it is a NE-trending mostly normal faulting event. The Earthly Musings blog has a nice entry on the Oak Creek Fault. Here is the earthquake on a compilation of active faults and earthquakes that I put together:
Here is the PDF. There have been some earthquakes in that area over the years.

Additional links:

I will continue to update as I learn more.

Monday, November 24, 2014

Planetary Volcanology field trip to the Pinacate Volcanic Field (November 22-23, 2014)

I joined a field trip to the Pinacate Volcanic Field in Northern Mexico this past weekend. It was a part of the Planetary Volcanology class taught by David Williams and Amanda Clarke. It was beautiful and very interesting. I had never been there, but just stared at it on google earth:

In this post, I present some field photographs from the tour, followed by a few slides from Amanda Clarke from a lecture on Water-Magma Interactions:

Crater Elegante

The Pinacates are in a biospheric reserve:
Crater Elegante: nice example of the phreatomagmatic features in great evidence.
Nice bomb sag in the surge units.
Amanda Clarke explaining the eruption-related features.
Model for Crater Elegante formation.
As we drove around, we saw some nice tephra that Amanda got excited about.

Conos Tecolote y Mayo

Overview looking south at the Sierra Pinacate. Note boundary between the more vegetated and tephra covered flow to left with fresher looking darker flow to right.

Cerro Colorado

View to the northeast looking at Cerro Colorado (feature to the right middle ground).
Cerro Colorado layered mostly surge deposits (view to east).
Cerro Colorado layered mostly surge deposits (note various clast compositions).
Cerro Colorado view towards the southwest; note nested "hippodrome" of late stage eruptive center(?).
Some lapilli--mostly armored, a few accretionary.

Water - Magma interactions

Amanda shared a few slides with me.
Cool slide showing the eruption energy versus water/magma ratio and the various phenomena and forms we may observe.
Forms versus eruption energy with increasing interaction with water.

Saturday, November 15, 2014

SoSAFE and Earthquake Geology Geochronology workshop report (Southern California Earthquake Center)

Kate Scharer (USGS), Mike Oskin (UC Davis) and I organized a geochronology workshop for the Southern California Earthquake Center community this fall. We emphasized methodologies useful for investigating fault slip behavior over time scales from 102 to 106 years. That included Terrestrial Cosmogenic Nuclides, Uranium Series, and Optically Stimulated Luminescence. We did not talk so much about 14C given its relative maturity, but we certainly recognize its continued value.

Kate lead the charge on the completion of the workshop report. It has a nice summary of the topics covered (here is the original agenda). I had a sense of a real acceleration in the number and quality of applications of the methods and the resulting rich depiction of deformation rates and their variations across time and space in Southern California. I was particularly moved by the climate modulation on the development of landforms (alluvial fans, channels, etc.) that serve as markers as well as the possible temporal coherence of wet and dry times across the region. I think that this modulation and coherence can be exploited with more intensive application of geochronology.

I learned a lot more geochronology, especially having just been at the EarthScope Geochronology Institute a week or so earlier--note that the talks and some of the videos are up (where we covered some similar topics and where Kate was a speaker on 14C). It was very nice to see many SCEC friends and colleagues.