Kyushu Japan Earthquakes April 2016

E-DECIDER is providing the following response products for the Kyushu earthquakes in Japan. More products to follow as are available. Image to the left shows the shaking intensity (courtesy of the United States Geological Survey – earthquake event page).
 

Resources


ETAS Aftershock Forecast Produced 14 April 2016

ETAS contours indicate the locations and magnitudes of recent earthquakes. Because of well known spatial and temporal scaling relationships, this also indicates the expected locations of earthquakes in the near future. In particular, ETAS based on sequences of small magnitude aftershocks may indicate the locations of large aftershocks that are not precisely co-located with the mainshock epicenter, as was the case with the 2015 Gorkha event, and to a lesser extent the  the 2016 Kyushu foreshock-mainshock sequence.

Download the files here.

Download the files here.


Risk Levels preceding the M6 on 4/14 and before the M7 on 4/15 using the Nowcasting method (provided by John Rundle, UC Davis)

Nowcasting is a term originating from economics and finance.  It refers to the process of determining the uncertain state of the economy or markets at the current time by indirect means.  We apply this idea to seismically active regions, where the goal is to determine the current state of the fault system.  In our implementation of this idea, we use the global catalog of earthquakes, using "small" earthquakes to determine the current state of progress through the “large” earthquake cycle in the region.  Our method does not involve any model.  Rather, we define a specific region and a specific large earthquake magnitude of interest, ensuring that we have enough data to span at least ~20 or more large earthquake cycles in the region.  We then compute the Earthquake Potential Score (EPS) which is defined as the cumulative probability distribution P(n<n(t)) for the current count n(t) of small earthquakes in the region.  From the count of small earthquakes since the last large earthquake, we determine the current value of EPS = P(n<n(t)).  This value assigns a number between 0% and 100% to every region so defined, and thus provides a unique measure.  Physically, the EPS corresponds to an estimate of the level of progress through the earthquake cycle in the defined region at the current time.

The following Nowcasts show the risk level for M>5 within a radius of 100 km of Kumamoto, which is using this new standard method for global cities.  Prior to the first M6 event, the computed risk level was 93% out of 100%.

Date: 

Thursday, April 14, 2016

Location: 

13 km WSW of Kumamoto-shi Japan