> Research Results > Release of "QuakeMap," a Wide-ranging Map Showing the Detailed Strong Ground MotionMasashi Matsuoka (Senior Research Scientist), GEO Grid Research Group (Leader: Satoshi Tsuchida), and Naotaka Yamamoto (Research Scientist), Grid Service-wear Research Group (Leader: Isao Kojima), the Information Technology Research Institute (Director: Satoshi Sekiguchi) of the National Institute of Advanced Industrial Science and Technology (AIST) (President: Tamotsu Nomakuchi), have developed the "Quick Estimation System for Earthquake Maps Triggered by Observation Records (QuiQuake)." QuakeMap, a part of QuiQuake, has been published in a web site since October 13, 2009. (http://qq.ghz.geogrid.org/index.en.html)
In this new system, an amplification capability map of ground motion (Vs30 map) based on a 250-m grid cell map of geomorphologic classification in Japan owned by AIST and seismic observation records from K-NET and KiK-net released by the National Research Institute for Earth Science and Disaster Prevention (NIED) are processed at high speed on a cluster computer of AIST. The system estimates and illustrates the wide-ranging and detailed ground motion of earthquakes immediately after the release of seismic observation records. Furthermore, strong ground motion maps for about 5,000 major earthquakes after June 1996 were computed and archived such that they chronologically represented the seismic motions over the last 13 years. It is expected that these maps will be used as fundamental information for municipalities and private companies to develop business continuity plans (BCPs) and to take effective countermeasures against seismic disaster. The results were opened to the public at the AIST Open Lab held in AIST Tsukuba on October 15 and 16, 2009.
 |
| Figure 1 Outline of the QuiQuake/QuakeMap System |
Currently, the seismic intensity information is released on the basis of the instrumental seismic intensity measured by approximately 4,200 seismographs installed throughout the nation. However, since the seismic motions vary depending on geologic and geomorphologic features, the ground motion at a location without a seismograph is not always consistent with the seismic intensity displayed by a seismograph close to the point. This is the reason why tourist spots that are included in the regions wherein the seismic intensity is announced suffer losses owing to the spread of false rumors. For instance, a reservation to a location may be cancelled even if there is no sensible ground motion at that location. Seismic damage does not obey administrative boundaries. In order for the national and local governments to understand all the facts regarding the damage caused by an earthquake, they need the seismic information beyond the administrative boundaries. Taking into consideration the BCPs of private companies that depend on the supply of goods, the companies require seismic information of not only the headquarters and branches but also of regions related to their supply chains such as locations of their suppliers and road networks. A first step for solving these issues can be to establish wide-ranging, seamless, and consistent precision data on amplification capability of ground and estimate and release the strong ground motion map of the concerned areas immediately after the occurrence of an earthquake.
AIST has continued to promote research and development on Global Earth Observation Grid (GEO Grid), an infrastructure for global observation data. GEO Grid is aimed at enabling users in fields including disaster mitigation and environment to easily process and analyze large archives including earth observation data in combination with various observation data and geographic information data stored at dispersed locations by using the grid technology. In addition, as a part of the research for the establishment of a "safe and secure society," AIST has developed monitoring active volcanoes using satellites, geological hazard assessment based on geologic and topographic features, simulation of volcanic pyroclastic flows, etc. With the aim of providing information to further mitigate disasters, AIST has developed a system for the immediate estimation of strong ground motions to try to generate valuable information in a timely manner by combining the information owned and released by other institutions with its own observation data and calculation resources.
As a first step toward understanding all the facts regarding earthquake damage in an affected region, it is important to grasp the distribution of seismic intensities. In order to obtain this information, it is necessary to establish the data related to amplification capability of ground motion in a wide area across administrative boundaries. In collaboration with NIED and the Kanto Gakuin University, AIST has created a 250-m grid cell map showing the geomorphologic classification of Japan, and then prepared the amplification capability data (Vs30 map) based on the map (Fig. 2). When an earthquake occurs, the seismic information recorded at the earthquake observation stations are released by the Japan Meteorological Agency and other related institutions. This two-dimensional amplification capability map allows us to estimate the ground motions in any region that is not equipped with a seismograph.
 |
| Figure 2 250-m grid cell map showing the engineering geomorphologic classification of Japan and amplification capability map (Vs30 map) |
The outline of this system is shown in Fig. 1. After the occurrence of an earthquake, the system gathers ground motions observation data from K-NET and KiK-net that are released on a FTP site by NIED and calculates the peak ground velocity (PGV) and equivalent instrumental seismic intensity. These values reflect the amplification of surface soil in a region in which a seismograph is located. Consequently, the amplification factors are first extracted and eliminated from the Vs30 map to estimate the PGV and the instrumental seismic intensity on base rock. Next, the distribution of the PGVs and the instrumental seismic intensities on base rock is calculated by spatial interpolation using characteristics of distance attenuation from a hypocenter as trend components. Then, the distribution of PGVs and instrumental seismic intensities on the earth's surface can be determined by multiplying them with the amplification factor in each of the 250-m grid cells. A schematic diagram of the calculation process is shown in Fig. 3.
 |
| Figure 3 Calculation process of spatial interpolation on a strong ground motion map |
Software was developed for automatic calculation and it was installed on AIST's GEO Grid Cluster Computer. This enabled us to provide wide-ranging and detailed PGVs and seismic intensities immediately after the release of seismic records. Furthermore, the Cluster's multi-task processing reduces the time for releasing information on the frequent aftershocks generated by major earthquakes. The main shock caused by an earthquake and its continued aftershocks in any region can be chronologically assessed on strong ground motion maps. These maps are expected to contribute to counter the false rumors resulting from limited information. Distributions of PGVs and instrumental seismic intensities concerning major earthquakes (approximately 5,000) after 1996 are determined, and the results have been released on the following Web site: http://qq.ghz.geogrid.org/index.en.html. The calculation results can be distributed by using Web Mapping Service, which helps in combining various types of information so that the results are efficiently used by the geographic information systems of local governments and private companies. Also, calculated values with location information can be downloaded for analyses by researchers and engineers.
The system is aimed at the immediate release of seismic information required to take the effective measures against disasters. Consequently, a strong ground motion map is calculated by a simplified method. The value estimated by the system has an error of approximately 0.6–1.7 times the actual value (0.232 in logarithmic standard deviation). Therefore, accurate estimations of ground motions must be carefully carried out at important infrastructures and certain specific places. It is desirable to use the map in conjunction with a method with a higher degree of precision based on the detailed ground survey data.
The "Quick Estimation System for Earthquake Maps Triggered by Observation Records (QuiQuake)" will be completed in FY 2010 utilizing "immediate open data" released in real time by NIED to provide seismic information faster. We aim at improvement in the functions of the system so that anyone can easily obtain ground motion information in any region immediately after the occurrence of an earthquake. In addition, we are willing to utilize other institutions' seismic observation records and enhance the precision of the data. By combining the data with distributions of populations, buildings, and roads, we hope to enable the system to estimate risks such as casualties and damages of constructions.
