Spatial organization of foreshocks as a tool to forecast large earthquakes

An increase in the number of smaller magnitude events, retrospectively named foreshocks, is often observed before large earthquakes. We show that the linear density probability of earthquakes occurring before and after small or intermediate mainshocks displays a symmetrical behavior, indicating that the size of the area fractured during the mainshock is encoded in the foreshock spatial organization. This observation can be used to discriminate spatial clustering due to foreshocks from the one induced by aftershocks and is implemented in an alarm-based model to forecast m > 6 earthquakes. A retrospective study of the last 19 years Southern California catalog shows that the daily occurrence probability presents isolated peaks closely located in time and space to the epicenters of five of the six m > 6 earthquakes. We find daily probabilities as high as 25% (in cells of size 0.04 × 0.04deg(2)), with significant probability gains with respect to standard models

'Suerte' (Luck): spirituality and well-being in El Alto, Bolivia.

This paper addresses the importance of faith and the consequent resort to supernatural forces to acquire a sense of well-being in a poor neighbourhood in the city of El Alto, Bolivia. Religious beliefs and practices have provided an important idiom for the expression of aspirations and the pursuit of ideals. The social role of emotions and its effect on well-being have been widely investigated in anthropology, especially in relation to issues of solidarity, feelings of confidence, and a sense of full personhood and empowerment (Barbalet 2001; Turner 2002; Bendelow and Williams 1997). The importance of faith is emphasised in my ethnography, showing how people’s loyalty to their notions of self-worth and the cosmological order is essential for their sense of fulfilment and empowerment. Thus, faith principles are fundamental to shed light on ideas of what people identify as well-being and fulfilment. My informants believe that luck can be controlled and changed by treating the spirits better. It can be bought and acquired by asking for protection from the spiritual forces living in the Bolivian plateau. Luck is inextricably connected with ideas of protection, destiny control and future aspirations. Bad luck is a moment of passage that leads to good luck. However, this is not a simple process. It requires a complex involvement of people, who carefully have to invest their time and money in changing their situation through various cultural practices of divination and control of destiny. Unless you are a breech baby, you are not born lucky, but you become so if you invest your resources in nourishing the forces that support the world. In exchange, these forces will assure and control an individual’s luck, freeing him/her from evil eye and envy-major sources of ill-being. This can be achieved through a ritual performed by a yatiri—local shaman, or other means, such as participating and dancing in a religious celebration in honour of a patron saint or engaging in regular acts of faith. The paper is based on ethnographic research carried out in Senkata, a poor neighbourhood in the city of El Alto, between November 2003 and November 2004. I spent 12 months in Bolivia in order to collect data for my Phd thesis. My methodology was mainly based on participant observation, informal conversations and a few formal interviews