paleoseismicity.org

What’s up? The Friday links (33)

Christoph Grützner — Fri, 18 May 2012 08:39:52 +0000

A very strange story happened in OC California some days ago (thanks @EricFielding for pointing me to that). A woman suffered serious burns because some rocks her kids found at a beach combusted spontaneously in her pocket. Immediately, a discussion started on twitter. What kind of rocks could that be? Hydrocarbon-bearing sediments? Coal? Phosphor? There have been some accidents with phosphor from World War II weapons that was washed upon the shore of the Baltic Sea. People confused it with amber. However, this is unlikely at California beaches. Mysterious rocks…

Crabs at a beach in Oman built these nice sand towers.

An interesting meeting:

From 17-20 September 2012 the XVI Wegener General Assembly will be held in Strasbourg, France. This will be an interesting meeting for all the earthquake people out there. Additionally, Strasbourg is a great place to discover French cuisine…

Soil memory:

The BGR (Germany’s Bundesanstalt für Geowissenschaften und Rohstoffe) published a soil memory online game on its website. If you want your children to become pedologists, let them play this game. Nice idea for educational purposes.

DIY low budget infrared camera:

Infrared cameras can reveal features invisible to the geologist’s eye, but they are still expensive. This website describes how to modify a low-budget camera to acquire infra-red pictures. If anyone has ever tried that and could report the results, I would be happy!

Geology rocks:

Okay, we’ve always known that, but it’s official now: Geology rocks. Geology students are the happiest. “95% of the quized students were satisfied with their courses.”

Archive of historical earthquake data:

AHEAD (Archive of Historical EArthquake Data) is a great resource for historical EQ data from 1000 – 1899 in Europe. The events can be sorted or accessed by clicking on a map. Additional data on the source are provided. We are waiting for a world wide archive now. However: Thanks, great job!

Video on combinign GIS and LiDAR data for rockfall hazard assessment:

Tom from RWTH Aachen University made a nice video on his and his colleagues work on Madeira Island, Portugal. There’s a serious rockfall hazard on Madeira (no wonder given the geology and the topography, just add 3,000 mm of annual rainfall in a subtropical climate and you can guess what happens), and they addressed that problem by LiDAR to measure joints and the geometry of basalt columns in urban areas:

Where on GoogleEarth:

If you need a break, have a look and try to solve my Where on GoogleEarth – WoGE #346!

Have a nice weekend!

Where on GoogleEarth? WoGE #346

Christoph Grützner — Tue, 15 May 2012 16:10:59 +0000

Matthew’s WoGE #345 looked pretty much like an ocean shoreline, but it turned out to be Lake Khanka located at the border of Russia and China. This lake is very shallow but has a large area and it is famous for its biodiversity and strongly influenced by flood events. There have been plenty of beach-WoGEs lately, so I decided to take you to another environment.

The rules:

Find the location of the image below.
Provide the coordinates in the comments.
Describe the geological significance of the spot briefly.
The first one to fulfill theses tasks is the winner.

The benefits:

Fame.
Fun.
The honour of hosting the next WoGE on your blog.

The drawback:

You might spend some time looking for the right spot instead of writing thesis, paper, proposal.

No Schott rule invoked. If you want to know more, read Felix’ summary.

Where is it?

What’s up? The Friday links (32)

Christoph Grützner — Fri, 11 May 2012 10:32:31 +0000

The INQUA has set up an Early Career Researchers Committee (INQUA_ECR), and I am proud being a member of that. Its aim is to support young scientists, to get young scientists involved in INQUA activities, to build up (scientific) networks, and to use social media. I think that’s a great idea, because up to now, you won’t find INQUA on Twitter, Facebook etc. We have set up a Facebook page now – come on in and like us, share links and find job offers! Twitter will follow soon. We will organize young scientists meetings at conferences (e.g. in Australia next year) and provide a lot of infos for early career scientists.

Monument Valley - what a great place.

Climate change and earthquakes:

I’ve come across an article stating that climate change will increase earthquake activity (and tsunamis) and the number of volcano eruptions. It’s from Yale and starts with discussing tectonics and ice ages (sure there is an increase in earthquake activity when Scandinavia goes down 800 m and pops up again within some thousand years!), but then makes it to quakes caused by varying air pressure and to climate change. Right after stating that there’s not enough data to do proper statistics, the clustering of mega-quakes during the last 8 years is mentioned as an indicator. Discussion will go on, I guess. What do you think?

Earthquake forecast in Utah:

The Wasatch fault in Utah has a huge potential to cause a disaster if it would rupture in a large earthquake. Salt Lake City for example might suffer substantial damage. Now, scientists claim to have enough data to set up an earthquake forecast like the Californians do. Good news!

Earthquakes in Azerbaijan:

Two M5.6 earthquakes have struck Azerbaijan on Monday. They caused some damage, but no fatalities as far as media reported.

Moment tensor solutions from EMSC.

Earthquakes are not unusual there, Ghanbari & Jalili, 2006 compiled several recent, historical, and pre-historical earthquake events in the broader area (Ghanbari & Jalili, 2006: Paleoseismicity and new seismicity studies in Azerbaijan and the necessity for seismic zonation. IAEG2006 Paper number 317).

Strange Sumatra Strike-Slip M8.6 EQ:

OurAmazingPlanet has a nice summary on why the huge strike-slip quake that occurred off Sumatra on 11 April was kind of strange and why it didn’t cause a tsunami.

How do earthqukae warnings work:

Have you ever wondered how earthquake warnings do work? Here’s a short article that explains the basics.

Low-frequency earthquakes in shallow depths can cause tsunamis at subduction zones:

Sugioka et al published a paper in Nature, describing how very slow earthquakes can accommodate strain at subduction zones. Those events may last up to 100s and happen close to the surface. Therefore, they can cause tsunamis. Previously, it was thought that convergence in that zones would occur aseismically. Sugioka et al, 2012: Tsunamigenic potential of the shallow subduction plate boundary inferred from slow seismic slip. Nature Geoscience, doi:10.1038/ngeo1466.

Re-photographing George Lawrence’s “San Francisco in Ruins”:

This is for sure one of the most spectacular photographs ever made. Some days after the 1906 San Francisco Earthquake, photographer George Lawrence shot a panorama of the devastated city. His masterpiece has now been re-photographed by USGS and a zoomable high-res version is online. You must see this!

Have a nice weekend!

SSA meeting in San Diego (& excursion to active faults!)

Christoph Grützner — Sun, 06 May 2012 21:02:27 +0000

Klaus and me went to the SSA 2012 annual meeting in San Diego in April. The conference was great and very focussed. I really like that kind of rather small meetings, where almost everything is interesting for me. I saw a lot of interesting posters and great talks and especially liked the paleoseismology and archeoseismology sessions (of course!).

Klaus at the SSA 2012 meeting

The session Earthquakes and Tsunamis at Coastal Archaeological Sites (chaired by Manuel, Beverly and Tina) had five interesting presentations on the broader Mediterranean area, and the talk from Klaus caused a huge media echo (more on this in a later post). With ground motions and site response dealt the session Macroseismic Effects in Recent and Ancient Earthquakes and their Relationship to Ground Motion Parameters. Especially Klaus Hintzen’s talk on modeling of the deformation observed in L’Aquila and Lorca caught my interest here. Good posters with a lot of fascinating trenching data could be found in the Neotectonics, Fault Geology and Paleoseismic Studies session. Additionally, the lunch was great and the organizers did a perfect job.

It was fun to meet some good friends and colleagues, and also to get to know new colleagues. I hope I can convince some of them to contribute to paleoseismicity.org in the future…

Tom Rockwell led one of the official excursions to the Elsinore Fault in southern California and showed fascinating geology and impressive fault features.

Where is the Elsinore Fault? Somewhere in that pretty hot desert...

There it is!

The fault had nice offset channels and some clear lithological contacts. A great feeling to stand at one of the most important tectonic features in Southern California, although we had around 40°C. Tom, however, managed to impress me even more the next day when we drove to Mexico and had a look at his work on the Laguna Salada Fault which ruptured in 2010, shaking large parts of Baja California!

Larger Map

This was just great, the surface ruptures were so impressive!

A beautiful cactus in front of an even more beautiful surface rupture.

What an offset, vertically more than 2 m at places, but varying a lot along the fault trace!

The fault trace is visible over dozens of kilometers.

A road side fence, offset by the 2010 magnitude 7.2 earthquake

The end of the faults, but surely not the end of the earthquakes there...

All in all, we had a great time, and a muchissima gracias goes to Tom for his hospitality and patience.

Active Fault Database for Northern Greece

Ioannis Papanikolaou — Sat, 21 Apr 2012 10:20:14 +0000

Databases for active faults are a major input for seismic hazard assessment and have been widely developed in several countries (such as USA, Japan, Italy and New Zealand). Despite the fact that Greece is the country of highest seismicity in Europe where almost 50% of the total seismic energy is realized, no official or unofficial active fault database exists. This is partly due to the fact that there are so many active faults that introduce a heavy workload, whereas several of them are also located offshore. This is particularly difficult for engineers since according to the latest the seismic building code that was released in 2000, no houses should be founded on active faults.

Such a detailed database has now been presented for Northern Greece by Sotiris Sboras who successfully defended his PhD at Ferrara University, Italy, under the supervision of Prof. Riccardo Caputo (University of Ferrara) and Prof. Spyros Pavlides (University of Thessaloniki). His thesis is available on line in the following link:

http://eqgeogr.weebly.com/2/post/2012/04/the-greek-database-of-seismogenic-sources-seismotectonic-implications-for-north-greece.html

Building up such a database is a painstaking process, it requires a detailed literature review, field-work experience and some expert judgment that inevitably introduces some subjectivity. Maintaining it and revising it, is a second difficult process. Each active fault database needs regular update and should be subject to change as new data and new interpretations become available, considering also that Earthquake Geology is a relatively new and emerging topic where such modifications are frequent.

Strike-slip week on Planet Earth

Christoph Grützner — Fri, 13 Apr 2012 10:34:54 +0000

Last week was really weird for earthquake geologists. We have seen one of the strongest earthquakes ever measured and another handfull of major events, all of them showing strike-slip fault movement. Manuel came up with the perfect description at his Planeet Aarde Geoblog: It’s strike-slip week on Planet Earth.

Mw8.6 Sumatra, 11 April

The most outstanding quake was of course the Mw8.6 Sumatra event of 11 April. Judging on the epicentre location and the magnitude, an ocean-wide tsunami was expected and an alert was published for the entire Indian Ocean coasts. Soon it became clear that the tsunami threat was overestimated and the warnings were cancelled. However, the systems performed well, and this is really good news. Naturally, everyone expected an earthquake of this magnitude to be a subduction megaquake. This would have lead to a significant offset of the seafloor and a tsunami. (I have been in Oman at this time and already looked for the best place to watch the waves approaching, really!) Then it turned out that we had a strike-slip event without significant movement of the water column. Only a small tsunami was observed. This event ranges number 11 in the list of the strongest events ever recorded by instrumental seismology.

Moment tensor solutions (EMSC image). Clear strike-slip with only minor vertical movement.

Slip distribution for the NE-SW fault plane solution: up to 7 m offset, up to 300 km rupture length (USGS image).

Mw8.0 Sumatra, 11 April

Only some 6 hours after this event, an Mw8.0 (or even more, see image) quake rocked the same area. What an aftershock – or was a second fault triggered? This will be interesting. I am expecting a lot of discussion on that. Again, we had a nice strike-slip movement.

The moment tensor solutions show a clear strike slip mode (EMSC image).

Just to summarize: This area experienced an incredible series of earthquakes since 2004.

2004 Mw9.1 (3rd largest event)
2005 Mw8.6 (9th largest)
2012 Mw8.6 (11th largest)
2007 Mw8.5 (13th largest)
2012 Mw8.0 (still large)

What an incredible release of energy.

M6.0 Oregon, 12 April

The US westcoast experienced an interesting M6.0 strike-slip event on the same day offshore Oregon:

M6.0 off Oregon. Yes, strike-slip.

Mw6.0 Gulf of California, 12 April

At 7:06 UTC Baja California was shaken by a moderate event, and again strike slip:

Magnitude Mw6.0, nice strike-slip in Baja California (EMSC image)

USGS even says it was M6.2.

Mw7.0 Gulf of California, 12 April

Ten minutes later, a Mw7.0 event occurred. I also expect some discussion on this and some really nice data. USGS reported the quake to have M6.9.

10 minutes after the 6.0 another earthquake rocked the Baja California area, again strike-slip.

I have to admit that this is an unusual accummulation of moderate to mega strike-slip events. Unusual? Yes, meaning that I don’t know about any comparable series. NOT meaning that the things we observed would be out of the statistical range. NOT meaning that Earth is trying to kill us. NOT meaning that the end is near. NOT meaning that we can not explain that. NOT meaning that HAARP or any other non-existing technology has been used. It’s just interesting and the data will be analyzed for lots of papers.

By the way, another strong EQ happened in Mexico (M6.5), but not strike-slip, and today is the 20th anniversary of the Roermond Earthquake that hit Germany, Belgium and the Netherlands with a magnitude of 5.9.

Have a nice and safe weekend.

Video on geological and geophysical field work in Greece – The dirt people reloaded

Christoph Grützner — Sun, 08 Apr 2012 14:20:20 +0000

I have made a video of our fieldwork in Greece, because I guess somehow we must communicate to the public what our work is about. Also, we must encourage young people to study geosciences. Well, now I concentrated on the second task: Hey, clever young people out there! Do you like science? Do you like nature? Are you interested in the big questions like “Where does this rock come from? When will the next earthquake happen? Where can I find groundwater? Why do volcanoes erupt? Which coast is threatened by Tsunamis?” Do you like to travel abroad, to work hard and to still have fun in the evenings? Do you want to meet nice people? If you answered “yes” to at least one of the above, think about studying geoscience.

Fallen columns at Ancient Olympia - does there hide an earthquake somewhere in the archaeological record?

This video was made in March 2012 in Greece, close to Ancient Olympia. A director’s cut with bonus stuff will follow maybe.

Since I am currently in Oman for teaching Geophysics to the great and curious students of GUTech‘s Applied Geoscience Programme, I need to mention that there is another video on fieldwork in Oman…

Happy Holidays everyone!

A motion piece on the Tōhoku Earthquake – One Year Later

Christoph Grützner — Sat, 07 Apr 2012 04:50:27 +0000

Peter Kim pointed me to that fascinating motion piece created by Onlineschools.org. It is an approach somewhere between science and art, but perfectly addresses a broad audience. It not only tells the story of the devastating earthquake and tsunami event, but also manages to raise attention to the recovery of the region.

What do you think about the movie?

PostDoc position in Quaternary Research/Paleoseismology, Lisboa, Portugal

Christoph Grützner — Fri, 06 Apr 2012 14:55:28 +0000

A postdoctoral position is open at ICIST-IST (Institute for Structural Engineering, Territory and Construction – Instituto Superior Tècnico) under the framework of the project FINDER – Fault Investigation with LiDAR for Earthquake Reassessment, PTDC/CTE-GIX/1138662009, funded by the Portuguese National Foundation for Science and Technology (FCT/MCTES). The position is for one year, applications should be sent to

Glenda Besana-Ostman (glenda.besana-ostman@ist.utl.pt) or
Patricia Pinheiro (patricia.pinheiro@ist.utl.pt)

For any information download the flyer here (PDF, English): postdoc2012.

Session on “Seismic hazard modeling”: 86th National Congress of the Società Geologica Italiana, 18-20 September 2012

Salvatore Barba — Thu, 05 Apr 2012 15:25:26 +0000

The Italian Geological Society (Societą Geologica Italiana), founded in 1881, organizes its 86th meeting in Calabria, Southern Italy (18-20 September 2012). The meeting is entitled

THE MEDITERRANEAN: A GEOLOGICAL ARCHIVE FROM PAST TO THE PRESENT

http://www.sgi2012.unical.it/info_eng.html

Within this meeting, we will held a session on Seismic Hazard Modelling.

We invite those of you interested to consider participating to the meeting and presenting an abstract (in ours or any other session).

The deadline for abstract submission is 30 April 2012.

TS2.1 – SEISMIC HAZARD MODELING

Conveners: Barba S., Di Bucci D., Gulen L., Pace B., Papanikolaou I., Valensise G., Visini F.

The purpose of the session is to discuss the factors that help to assess the regional and local seismic hazard in the Mediterranean region. We encourage works that present new data (active tectonics, geodetic measurements, hydro and geochemical observations, new dating techniques, historical and instrumental seismicity, site effects, earthquake effects on people and environment), and different methodological approaches (methods based on deformation and/or slip rates, classical and/or innovative seismotectonic methods, classical and/or innovative probabilistic methods). We welcome methodological discussion and applications to large towns and critical infrastructures, as well as case studies on the Calabrian Arc, where large and frequent earthquakes occur.