Science of Slow Earthquakes

Science of Slow Earthquakes - Toward a unified understanding of all earthquake events from low-speed deformation to high-speed slip

Events / Activities2017

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Dec. 11-15, 2017
Related session at AGU FALL MEETING 2017

Meeting AGU FALL MEETING 2017 (Official website)
Date 2017/12/11-15
Venue New Orleans Ernest N. Morial Convention Center
Details Slow Earthquakes related session:
S019: Slow slip, Tectonic Tremor, and the Brittle-to-Ductile Transition Zone: What mechanisms control the diversity of slow and fast earthquakes?
Program Posters:
S41C: Slow Slip, Tectonic Tremor, and the Brittle-to-Ductile Transition Zone: What Mechanisms Control the Diversity of Slow and Fast Earthquakes? I Posters

S52B: Slow Slip, Tectonic Tremor, and the Brittle-to-Ductile Transition Zone: What Mechanisms Control the Diversity of Slow and Fast Earthquakes? II

S53F: Slow Slip, Tectonic Tremor, and the Brittle-to-Ductile Transition Zone: What Mechanisms Control the Diversity of Slow and Fast Earthquakes? III

S54C: Slow Slip, Tectonic Tremor, and the Brittle-to-Ductile Transition Zone: What Mechanisms Control the Diversity of Slow and Fast Earthquakes? IV

Sep.19-21, 2017
Information updated for the Joint Workshop on Slow Earthquakes 2017 in Matsuyama city, Ehime prefecture

Date 2017/9/19-21
Venue Hotel MYSTAYS Matsuyama, Matsuyama city, Ehime prefecture
(formerly "Hotel JAL City Matsuyama")
Details Planned schedule
Sep. 19 (Tue.) 9:00 - Sep. 21 (Thu.) 15:00
Field trip (Sep. 22-23, Sambagawa, central Shikoku)
Workshop site
The joint workshop on slow earthquakes this year was held from September 19th to 21st, 2017 at Matsuyama city, Ehime prefecture, the mecca of slow earthquakes where deep low frequency tremors occur directly beneath.
Another reason why we decided to hold the workshop in Matsuyama is the JGS 2017 was planned at the Ehime University, Matsuyama city right before our workshop.
Unfortunately, the session on slow earthquakes at the JGS 2017 and the lecture for the public jointly planned on September 17th with the MEXT Grant-in-Aid for Scientific Research on Innovative Areas "Interaction and Coevolution of the Core and Mantle" were both cancelled due to the typhoon.
Our workshop was held as planned with 130 participants including 18 researchers from overseas. There were 43 oral and 60 poster presentations on wide diversity of studies such as seismology, geodesy, geophysics, geology, nonlinear physics, mathematical statistics. That shows that we need many different approaches from various point of views to understand slow earthquakes.
As I mentioned at the closing remarks, when I first found a deep low frequency tremor, a strange vibration similar to a tremor was monitored in the Tokai area. I assumed it was vibration due to a mud volcano eruption looking at the location of estimated hypocenter and surrounding geological environment.
The presentation on relationship between mud volcanoes at the workshop and slow earthquakes shows a new approach to slow earthquakes as well as reminded me of that finding 20 years ago.
Reported by Kazushige OBARA
Report on the field trip
After the joint workshop in Matsuyama city, Ehime prefecture, some participants took part in the field trip to Sanbagawa Belt guided by Professor Wallis of Nagoya University, a co-investigator in Group B02. We observed metamorphic rocks along the Asemigawa river in Kochi prefecture on Day 1 and along the Kokuryogawa river in Ehime prefecture on Day 2. Total of 20 participants included researchers and students both from Japan and overseas with a wide variety of research fields such as geology, non-linear physics, seismology and mathematical statistics. For those who are not geologists, it was exciting to see the hydration and dehydration process in the subduction zone. Active discussions took place on the reaction speed and fluid migration velocity. Colors of metamorphic rocks vary depending on what they were formed from. The findings from the field trip would accelerate multidisciplinary discussions on interactions between rocks and fluids in source areas of slow earthquakes. (Akiko TAKEO, Group A01)

From the partticipants
The purpose of the slow earthquake fieldtrip was to observe structures that are likely to be related to slow earthquake formation in the Sanbagawa paleosubduction zone. Many of the talks during the slow earthquake workshop had focused on indirect observations of the subduction zone theorizing the different possibilities that might cause slow earthquakes. A few key concepts that stuck to my mind from the talks given during the conference were the role of coupling in the subduction zone and the role of fluid consuming and releasing mineral reactions. Looking at the Sanbagawa rocks we had a tangible chance to peer into the actual geology of a paleosubduction zone. The interplay of brittle and ductile deformation was something I tended to pay attention to, as this was a major point that the concluding talk of Ake Fagereng had focused on. On the first day we explored three locations in Asemigawa. The first outcrop, known as Kameiwa, is made up of folded siliceous and pelitic schists (Fig. 1). Many peoples interest was focused on the quartz veining cutting though the foliation as this can be seen as a sign of brittle fracturing in the subduction zone as well as a pathway for fluid flow. At the second locations we could see foliated mafic schists and quartz schist as well as structures resembling metamorphosed pillow lavas. Quartz veins were observed also at this location but folding was less pronounced.
The last location of the day was a river ravine with blocks of sedimentary/volcanic breccia (Fig. 2). These rocks were actually part of the Mikabu belt but had been overprinted by the Sanbagawa metamorphisim. Large rounded oblong clasts were oriented in the same directing showing ductile deformation of the matrix. The clasts themselves displayed brittle fracturing that was often filled by calcite. The day was topped with a lovely Japanese style dinner with many interesting dinner conversations!
The second day we headed to Kokuryogawa. The rocks seen on this day were higher metamorphic grade representing an area deeper in the subduction zone. At the first outcrop we looked at a metapelite that is located close to the Median Tectonic line showing structures that display brittle and ductile deformation. Figure 3 shows several normal faults that are bounded by a common layer in the metapelite in the bottom and marble vein on the top. It looks as though that during this deformation event the metapelites faulted in a brittle manner and the marble vein deformed in a ductile manner.
The second location of the day was the Tonaru metagabbro. These rocks represent the highest metamorphic grade found in the Sanbagawa belt. Here we could see amphibolite and zoisite rich layered rocks that are metamorphosed from a gabbroic protolith. These older gabbroic rocks spent a long time in the subduction zone being heated up. Large slowly growing garnet crystals, which were largely replaced by amphibole pseudomorphs, provide evidence for this. The final stop of the field trip was the Minetopia mine museum and the adjacent serpentinite rocks (Fig. 4). The serpentinites are of special interest in the Sanbagawa belt because they are though to be from the mantle wedge. The area of mantle wedge is especially interesting to slow earthquake research because this is where we can observe deep episodic tremor and slip. Serpentinite is a hydrated from mantle peridotite and mineral reactions in this region have a big impact on the fluid budget of the deep subduction zone. Examples of mineral such reactions can be seen also at this outcrop where serpentinite is chloritized.
Many thanks to Professor Wallis for guiding and organizing the trip and big thanks also for the organizers of the Slow Earthquake Workshop! (Ilona Sakaguchi, Nagoya University)
Figure 1. Fieldtrip members at Kameiwa
Figure 2. Sedimentary/volcanic breccia
Figure 3. Normal faulting bounded by a marble vein. Prof. Wallis for scale.
Figure 4. Fieldtrip members exploring the serpentinite.

We visited many parts of the Sanbagawa Belt, one of the paired metamorphic belts in Shikoku island, located at the south of the Median Tectonic Line. The Sanbagawa Belt consists of rocks that are metamorphosed under high pressure and low temperatures in comparison to the adjacent belt, the Ryoke---Abukuma Belt, with high pressure and high temperature metamorphic rocks. On the first day, we visited Kameiwa and pillow lavas, and on the second day we stopped at three nteresting sites. One of them was Kokuryogawa with normal fault duplex, followed by Tonaru Metagabbro with rocks containing beautiful garnet crystals, and finally we visited an exposed outcrop of the mantle wedge with Serpentine rocks. (Deepa Mele Veedu, Nanyang Technological University)

The field trip to Sanbagawa belt was well-organized and a very interesting complement to the Joint Workshop on Slow Earthquakes in Matsuyama. Simon Wallis brought us to the most representative outcrops to illustrate the main geological features of the Sanbagawa metamorphic belt and explained detailed features of the rocks and how the metamorphic conditions can be determined by the structure and mineral componentry of the rocks. My main research field is developing statistical models to capture distinct features of seismic data. Metamorphism and seismicity belong to the same continuum of tectonic processes, and hence this trip was great to visualize the link between the ancillary data that I study and the geological processes that are their fundamental cause. (Ting Wang, University of Otago)

Sep.16-18, 2017
Related session at the 124th Annual Meeting of the Geological Society of Japan: 2017 Ehime

Meeting The 124th Annual Meeting of the Geological Society of Japan: 2017 Ehime (Official website)
Date 2017/9/16-18
Venue Ehime University Johoku Campus
Details Slow Earthquakes related session: T7. Geology of Slow Earthquakes

September 15, 2017
Friday Seminar by Dr. Abhijit Ghosh

Time/Date 16:00-17:00, September 15, 2017
Venue Conference room #1, 5th floor, Building 2, ERI: Access Map
Speaker Dr. Abhijit Ghosh (University of California, Riverside)
Topic "Global observation of a wide spectrum of earthquakes"

Jul.30-Aug.07, 2017
Related session at IAG-IASPEI 2017

Meeting IAG-IASPEI 2017 (Official website)
Date 2017/7/30-8/7
Venue Kobe International Conference Center
Details Slow Earthquakes related session: J06 The spectrum of fault-zone deformation processes (from slow slip to earthquake)
Convener : Hitoshi Hirose (Kobe University, Japan)
Co-convener : Yoshihiro Ito (Kyoto University, Japan),
Chris Marone (Pennsylvania State University, USA)

July 29, 2017
Slow Earthquakes Cafe in Kobe

We will hold the first Slow Earthquakes Cafe in Kansai area at Kobe University.
Please join us for a talk by Dr. Chris Marone before IAG-IASPEI 2017.

Time/Date 14:00-16:00, July 29, 2017
Venue Room #103, Building Z, Faculty of Science, Kobe University: Access Map
Speaker Dr. Chris Marone (Pennsylvania State University)
Topic "The Spectrum of Fault Slip Behaviors and The Mechanics of Slow Earthquakes: A View From The Laboratory"

July 21, 2017
Dr. John Vidale and Dr. Heidi Houston visited Dr. Obara, the project leader of "Science of Slow Earthquakes."

Dr. John Vidale and Dr. Heidi Houston at the University of Washington dropped by the ERI to see Dr. Obara, the project leader of Science of Slow Earthquakes after an international workshop held at Misasa town, Tottori prefecture. They are globally notable seismologists who also have many achievements on slow earthquakes and have been working together with Dr. Obara. Dr. Kevin Chao, who gave a talk at the Slow Earthquakes Cafe on the previous day, also came by to see them. The latest research on slow earthquakes such as triggered tremors was discussed in Dr. Obara's office. Dr. Vidale is to be a new director at the Southern California Earthquake Center (SCEC) soon.

July 20, 2017
Slow Earthquakes Cafe

Please join us for the talk about slow earthquakes with soft drinks and snacks.
The meeting rooms will be open at 16:00. Please enjoy conversation with the speaker over a cup of coffee before the talk.

Time/Date 16:30-18:00, July 20, 2017
(16:00-16:30 Free talk with the speaker)
Venue Meeting room A&B, 3rd floor, Building 1, ERI: Access Map
Speaker Dr. Kevin Chao (Northwestern University)
Topic "Dynamic Triggering of Tectonic Tremor: What are the similarities and differences between triggered and ambient tremor?"

On July 20, we invited Dr. Kevin Chao of Northwestern University, U.S.A. as the speaker at the Slow Earthquakes Cafe and Bar.
Dr. Chao is from Taiwan. He stayed at the ERI as a postdoctoral researcher for 2 years after he received his Ph. D from Georgia Institute of Technology. At the ERI, he conducted a joint research with Dr. Obara, the project leader of slow earthquakes, on deep low frequency tremors occurring at various locations in Japan. After staying at the ERI, he spent few years at MIT then now belongs to Northwestern University. Dr. Kevin Chao is the world's leading researcher in the field of tremors triggered by remote seismic surface waves. At the cafe, he gave a talk on general explanation about tremors, world distribution of triggered tremors and the mechanism.

July 20, 2017
Seminar by Dr. Osbanny Ramos

Time/Date 11:00-12:00, July 20, 2017
Venue Meeting room #2, 2nd floor, Building 2, ERI: Access Map
Speaker Dr. Osbanny Ramos (University of Lyon)
Topic "Modelling Earthquakes with a Granular Experiment"

May 20-25, 2017
Related session at JpGU-AGU Joint Meeting 2017

Meeting JpGU-AGU Joint Meeting 2017 (Official website)
Date 2017/5/20-25
Venue Makuhari Messe
Details Slow Earthquakes-related sessions: S-SS04: Subduction zone dynamics from regular earthquakes through slow earthquakes to creep
Oral sessions: 5/24 (Wed.),25 (Thu.) 9:00-15:15 at A10
Link to the program
Poster core time: 5/25 (Thu.) 15:30-18:30 at Poster Hall

At JpGU-AGU 2017 we co-hosted the session " Subduction zone dynamics from regular earthquakes through slow earthquakes to creep." On May 24th and 25th, 24 oral presentations, including the ones by overseas invited speakers (Jessica Hawthorne, Lisa McNeill, Donna Shillington, Matt Ikari, William Frank, Eric Dunham and Onno Oncken, were given. Since it was the first joint meeting with AGU, there are lots of international visitors and we had fruitful presentations and discussions in English. Holding 65 poster presentations, we were the largest scientific session in the meeting. We hope active discussions on the meeting may lead new achievements on the study.

Reported by Satoshi IDE

Poster presentation

General meeting of the project

Apr.23-28, 2017
Related session at EGU General Assembly 2017 in Vienna, Austria

Meeting European Geoscience Union General Assembly 2017 (Official website)
Date 2017/4/23-28
Venue Austria Center Vienna
Details Slow Earthquakes-related session: SM2.2/EMRP4.13/GD5.8/NH4.13/TS5.7: Understanding large subduction earthquakes by integrating geological and geophysical observations, laboratory results, and numerical modeling (co-organized)
Orals / Mon, 24 Apr, 13:30-17:00 / Room -0.96
Posters / Attendance Mon, 24 Apr, 17:30-19:00 / Hall X3

I attended to European Geosciences Union (EGU) General Assembly 2017 for the first time as a guest speaker invited by Dr. Jean-Pierre Vilotte of Institut de Physique du Globe de Paris (IPGP). The session "Understanding large subduction earthquakes by integrating geological and geophysical observations, laboratory results, and numerical modeling" was jointly held with the Tohoku earthquakes session. My lecture was based on the paper published in Science last year. Many members in our research area gave presentations based on observations in the coast of the Tohoku area. On the other hand, many speakers from Europe did presentations about modeling and experiments. 50 copies of our Newsletter Vol. 1 placed in the booth of the ERI run out on the first day. It suggests that certain number of researchers are interested in the Science of Slow Earthquakes.

Reported by Kazushige OBARA
Vienna International Centre, the EGU venue

Apr. 20, 2017
"Science of Slow Earthquakes" was introduced as a highlighted research in Handbook2017 of the Earthquake Research Institute, the University of Tokyo (p. 17).

Mar.17, 2017
Related symposium at annual meeting of the Physical Society of Japan (JPS)

Program (in Japanese) :

Feb.21-22, 2017
Groups C01/C02 joint workshop was held.

Date 2017/02/21-22
Venue Large conference room A, Kyushu University Nishijin Plaza
Program FEB 21
13:00 - 13:10
welcome (Ide)
13:10 - 13:40
Ide "The scaling law for slow earthquakes, revisited"
13:40 - 14:10
Maury "Slow earthquakes study along the Mexican subduction zone" 14:10 - 14:40 Yoshioka "Three-dimensional numerical modeling of temperature and dehydration fields associated with subduction of the Philippine Sea plate, southwest Japan"
14:40 - 15:00
15:00 - 15:30
Matsuzawa "Numerical simulation of slow slip events considering the effect of earth tides and plate configuration"
15:30 - 16:00
Ando "Fault rheology and diffusive propagation of slow earthquakes" 16:00 - 16:30 (break)
16:30 - 17:00
Okuwaki "Rupture process during the 2015 Illapel, Chile earthquake: Zigzag-along-dip rupture episodes in relation with swarms"
17:00 - 17:30
Suzuki "Derivation of Analytical Form for the Solution Orbit in the System of the Interaction among Heat, Fluid Pressure and Dilatancy"
17:30 - 18:00
Yabe "Tidal sensitivity of tectonic tremors"
FEB 22
09:00 - 09:30
Yamaguchi "Fast to slow slip transitions of gels having controlled surface asperities"
09:30 - 10:00
Sumino "Construction of experimental toy model for slow earthquake with soft condensed matter"
10:00 - 10:30
10:30 - 11:30
Elbanna "Shear and Vibrations in confined gouge - Implications of acoustic vibrations on localization, triggering and slow slip"
11:30 - 12:00
Ariyoshi "Characteristics of frictional properties - dependency on slow earthquake migration speed"
12:00 - 13:30
13:30 - 14:00
Fukuyama "Precursory Slow Slip and Foreshocks in Lab Experiments"
14:00 - 14:30
Yamashita "Influence of fault surface condition on slip stability in large-scale biaxial friction experiment"
14:30 - 15:00
15:00 - 15:30
Xu "Laboratory investigation of fault motion along a metagabbro-marble interface"
15:30 - 16:00
Hatano "Scale dependence of rate and state friction"

C01/C02 joint workshop was held on February 21-22 in Fukuoka city, Kyushu. The first workshop of C01 was co-hosted by C02, which is organizing various activities. We chose Fukuoka as a venue because Dr. Ahmed Elbanna of the University of Illinois whom we invited for our research field was staying at Kyushu University during that period. The 2-day workshop consisted of the keynote lecture by Dr. Elbanna, lectures by 14 members of both C01 and C02 in English and active debates. There introduced leading-edge studies in approaches to slow earthquakes from different perspectives such as, tremor observation, mathematical models and large-scaled rock experiments.
Dr. Elbanna is a young and energetic researcher studying law of friction in granular materials. Although he has not mainly focused on slow earthquakes, his fundamental works have potential to provide better understanding of slow earthquakes. He said he got more interested in slow earthquakes during his stay in Japan this time. We hope we will have further cooperation.

Jan.13, 2017
Observation groups workshop was held.