Possible Origin of Memory in Earthquakes: Real catalogs and ETAS model

Earthquakes are one of the most devastating natural disasters that plague society. A skilled, reliable earthquake forecasting remains the ultimate goal for seismologists. Using the detrended fluctuation analysis (DFA) and conditional probability (CP) methods we find that memory exists not only in inter-occurrence seismic records, but also in released energy as well as in the series of the number of events per unit time. Analysis of the conventional earthquake model (Epidemic Type Aftershock Sequences, ETAS) indicates that earthquake memory can be reproduced only for a narrow range of model's parameters. This finding, therefore provides additional accuracy on the model parameters through tight restrictions on their values in different worldwide regions and can serve as a testbed for existing earthquake forecasting models

The IASLC Lung Cancer Staging Project: A Renewed Call to Participation

Over the past two decades, the International Association for the Study of Lung Cancer (IASLC) Staging Project has been a steady source of evidence-based recommendations for the TNM classification for lung cancer published by the Union for International Cancer Control and the American Joint Committee on Cancer. The Staging and Prognostic Factors Committee of the IASLC is now issuing a call for participation in the next phase of the project, which is designed to inform the ninth edition of the TNM classification for lung cancer. Following the case recruitment model for the eighth edition database, volunteer site participants are asked to submit data on patients whose lung cancer was diagnosed between January 1, 2011, and December 31, 2019, to the project by means of a secure, electronic data capture system provided by Cancer Research And Biostatistics in Seattle, Washington. Alternatively, participants may transfer existing data sets. The continued success of the IASLC Staging Project in achieving its objectives will depend on the extent of international participation, the degree to which cases are entered directly into the electronic data capture system, and how closely externally submitted cases conform to the data elements for the project

Crustal structure of the Dead Sea Basin from local earthquake tomography

International audienceNew findings of the velocity structure of the crust across the Dead Sea Basin are obtained by applying tomography-based method to local earthquakes. We use P-wave traveltime of 614 earthquakes that occurred in the Dead Sea Basin in 1983-2009. At all depths, the Dead Sea Basin is characterized by lower velocities relative to both the eastern and western sides of the basin. There is significant seismic activity at a depth of about 20 km, mainly in the centre and the northern part of the basin. At shallow depths (<15 km) there is more seismic activity on the eastern side of the basin than on the western side, and the northern basin is generally more active than the southern basin. Asymmetry is also observed in the faults that border the Dead Sea Basin. The Arava Fault on the eastern side, with nearly vertical dip faulting, appears to be a clear boundary at all depths down to about 20 km. The depth extension of the Jericho Fault on the western side of the basin is definitely limited to less than 15 km. At greater depths of 20 km or more, the western side is only partially bounded by a fault. The concentration of earthquakes in the central part of the basin at depths larger than 15 km suggests that the Dead Sea Fault at those depths acts as one single fault that is located in, or near, the central axis of the basin. The existence of a number of clusters of earthquakes that spread from shallow depths of a few kilometres up to a depth of about 22 km, points to several defined faults that traverse the Dead Sea Basin. One such example is the aftershock sequence of the 2004 earthquake that occurred in the northern Dead Sea Basin. Seismic activity near Mt Sodom is relatively low and occurs at shallow depths down to 10 km, whereas at larger depths (≥15 km) it ceases. This implies that the whole structure is relatively shallow with no wide and deeper extension. Seismic activity near and within the Lisan Peninsula extends to somewhat larger depths (∼15 km), and then it ceases. The occurrence of earthquakes at large depths suggests that the upper and the lower crust are relatively cool, as was also suggested by earlier studies, pointing to the fact that the heat flow is significantly below the global average value

Stress tensor and focal mechanisms along the Dead Sea fault and related structural elements based on seismological data

International audiencehe Dead Sea fault is among the largest active strike–slip fault of the world. This study is focused on the southern part of this fault, from the Sea of Galilee to the Gulf of Aqaba, as monitored mainly by the Jordanian and Israeli seismic networks. The data of arrival times and polarities allowed relocation of earthquakes with a better azimuthal coverage and computation of focal mechanisms. This last step has been realized by inverting the polarities to determine a unique stress tensor for the region and the compatible focal mechanisms. Inversion with different subsets of the data set, based on tectonic regionalization, has also been performed to evaluate the impact of each cluster of earthquakes on the global solution. The population of focal mechanisms is clearly dominated by strike–slip events, with the notable exception of a cluster of earthquakes, south of the Dead Sea, which displays several normal focal mechanisms. This last cluster forces σ1 to be vertical and σ2 to be horizontal. A large number of fault planes, however, are close to the vertical, inhibiting the action of the vertical component of the stress tensor, and acting like under strike–slip stress regime. We observed a good agreement between the location of the earthquakes and the active faults, based on geological data. In addition, there is a good agreement between the fault plane solutions and the orientation of the active faults

Scaling laws in earthquake memory for interevent times and distances

Over the past decades much effort has been devoted towards understanding and forecasting natural hazards. However, earthquake forecasting skill is still very limited and remains a great scientific challenge. The limited earthquake predictability is partly due to the erratic nature of earthquakes and partly to the lack of understanding the underlying mechanisms of earthquakes. To improve our understanding and potential forecasting, here we study the spatial and temporal long-term memory of interevent earthquakes above a certain magnitude using lagged conditional probabilities. We find, in real data, that the lagged conditional probabilities show long-term memory for both the interevent times and interevent distances and that the memory functions obey scaling and decay slowly with time, while, at a characteristic time, the decay crossesover to a fast decay. We also show that the ETAS model, which is often used to forecast earthquake events, yields scaling functions of the temporal and spatial interevent intervals which are not consistent with those of real data