Fractures predominantly

strike NW-SE to NNW-SSE with dip angles between 60° and 90° (Hautmann et al., 2010). Montserrat has a subtropical maritime climate. The average annual temperature at sea level is 25.9 °C and average monthly temperatures range between 24 and 27 °C. Temperatures peak in August and are generally lowest in February (Fig. 2). Temperature also varies with elevation. Blume et al. (1974) suggest an average reduction in air temperature of 0.6 °C per 100 m of altitude for the Caribbean islands. Unfortunately, there is not sufficient temperature data to define CX5461 an independent relationship for Montserrat. The island experiences both local convective storms and intense rainfall associated with larger tropical weather systems (Barclay et al., 2006). Historical data acquired from the archives of Monserrat Utilities Ltd (MUL) demonstrates

that, while rainfall is common throughout the year, a clear seasonality does exist (Fig. 3). The wet season extends from July to GSK3 inhibitor November, with rainfall totals decreasing through December and January into a dry season from February to April. The end of the dry season is often marked abruptly by high rainfall through May, before a more steady increase in monthly precipitation to a maximum in Gemcitabine purchase the months of September, October and November. While frequent, year round, high intensity but short (minute-hour) convective storms provide much of the baseline precipitation on the island, tropical storms and hurricanes are responsible for significant additional precipitation associated with the wet season peak. In 2010 Hurricane Earl passed 150 km off the east coast of Montserrat, delivering almost 10% of the recorded annual rainfall at Hope rain gauge, in just a few hours.

There is also significant interannual variation in rainfall on Montserrat, complexly related to sea surface temperatures in the eastern Pacific Ocean (El Nino-La Nina), as well as in the tropical and subtropical Atlantic Ocean (Barclay et al., 2006). Historic data from a pre-eruption rain gauge at Grove in Plymouth (location of rain gauges displayed in Fig. 4) provides monthly totals spanning 47 non-consecutive years between 1902 and 1965. The total annual rainfall for this period ranges from 1139 to 2000 mm with a mean of 1543 mm and standard deviation of 237 mm. The distribution of precipitation also varies spatially (Fig. 4). Unsurprisingly, on this steep, volcanic island a significant topographic variation in rainfall exists. Barclay et al. (2006) suggested that the mountain tops receive 60% more rainfall than the lower-lying coastal areas.