The need for the rapid association of earthquake phase arrivals arises as one of the major requirements of rapid notification systems. The primary goal of an earthquake early warning system is to warn critical facilities of impending strong ground shaking after rupture in the source region has commenced, but before the arrival of seismic energy (Heaton, 1985;Ellsworth and Heaton, 1994). Recent advances in computer and communications technology make such systems both feasible and practical. Toward this end a phase association algorithm, based on stacking the time-reciprocal regional travel-time function, has been developed; forming the basis of the Auryn phase associator. Earthquake catalogs are adjusted, and locations are recalculated, in real-time as each phase is received. The design is such that hypocenters can be calculated and plotted during vigorous swarms and aftershock sequence.Future potential applications include shortening of the alarm times prior to large earthquakes, processing amplitude data along with phase arrivals, providing a more robust method of associating phase from sparse regional networks (with possible application to nuclear test ban monitoring, and the association of teleseismic phases from global networks.

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The phase diagrams of the systems lithium iodide-potassium iodide and lithium iodiderubidium iodide have been determined by using the thermal analysis technique together with calculations based on a model proposed by Lumsden. The lithium iodidepotassium iodide system is a simple eutectic, the eutectic occurring at 285OC. and 63.5 mole Yo Lil. In the lithium iodid+rubidium iodide system, a peritectic occurs at 260OC. and 56.15 mole Yo Lil, and a eutectic occurs at 252OC. and 62.0 mole Yo Lil.W H E N MIXED with lithium iodide, potassium iodide and rubidium iodide form low-melting eutectics. Further, their thermodynamic stability in the presence of molten lithium metal indicates the potential application of these salt mixtures as electrolytes for the lithium-chalcogen cells being developed in this laboratory ( 1 , 2 , 10). The phase diagram for the LiI-KI system has been reported by Leiser and Whittemore (6) and by Liu and Lieto (7). The lack of agreement between these data has been resolved and new data are given for the LiI-RbI system. EXPERIMENTALThe lithium iodide was obtained from two sources. Material from Anderson Physics Laboratories was purified by the Laitinen et al. ( 5 ) method of purging with H I and argon in the molten state, and evacuation to remove the last traces of moisture. The other material was obtained as the trihydrate from Foote Mineral Co. The pure LiI.3H20 was dehydrated under vacuum in stages of increasing temperature over a period of two weeks. The LiI thus produced was melted and filtered through a fine quartz frit. The salt was tested for dryness by introducing molten lithium held on a stainless steel sponge. The absence of gas evolution confirmed the dry state of the lithium iodide. Portions of the salt were dissolved in distilled water. The pH of the resulting solution was the same as distilled water, indicating the absence of lithium oxide or lithium hydroxide. Potassium iodide and rubidium iodide were dried by similar programmed vacuum drying of the reagent-grade materials; their dryness and basicity were tested as before by introduction of molten lithium and pH measurement of a water solution of the respective salt.The solid-liquid equilibrium temperatures in the LiI-K I and LiI-RbI systems were determined by thermal analysis techniques. Cooling rates varied from 1.2" to 2°C. per minute. All the experiments were carried out in furnace wells attached to the floor of a high-purity helium atmosphere box ( 4 ) . Weighed amounts of the respective iodides were placed in the crucible and heated to 500" to 6OO0C. with stirring until a homogeneous melt was formed. The sensing thermocouple was calibrated against NBS pure tin (m.p. 231.88"C.). In all cases, the thermal arrests a t the liquidus and solidus were reproducible to within + l°C . RESULTS AND DISCUSSIONThe phase diagrams of the two binary systems are given in Figures 1 and 2; the experimental data are presented in Table I. With these minimal data and calculations made using a model proposed by Lumsden (8, 9 ) , the complete binary ...

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