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The study analyzed the raindrop size distribution (DSD) measured by an optical Parsivel disdrometer in Southern Luzon, Philippines and utilized it to generate dual-pol relations for the nearby Tagaytay radar. The relations were generated using two methods (Method 1 - gamma-based and Method 2 - linear fitting), four time-integration steps (1-, 2-, 5-, and 10-minute) and datasets from two periods (wet season and single event). The resulting quantitative precipitation estimates (QPEs) calculated from the generated R(Z) relations were compared to rain gauge stations near the disdrometer and were evaluated for the Tropical Storm Yagi Monsoon event of August 10 (2200 UTC) to August 11 (0400 UTC), 2018 using six statistics: Pearson's correlation; mean error, percent bias, Nash-Sutcliffe Efficiency, mean absolute error, and root-mean-square error. Results show that the area's DSD demonstrates relatively larger average raindrop diameters than some of its Asian counterparts, albeit a smaller number in the total number of raindrops when compared with the same areas. In terms of QPE evaluation, results showed a consistent pattern observed wherein the R(Z) relations using finer time steps (1-min and 2-min) generally performed better than the longer ones. Moreover, Method 1 dominated Method 2 in terms of error statistics. As expected, Method 2 outperformed Method 1 in terms of r (as Method 2 itself is derived through linear fit). The best derived R(Z) relations were able to outperform other relations in terms of r, NSE, and RMSE. On the other hand, R(KDP) was able to perform the best in terms of ME, MAE, and pBIAS, reducing the bias of current standard method by up to 74%. [ABSTRACT FROM AUTHOR]

This paper presents the first field, geochemical and geophysical information on the recently recognized Early Cretaceous Balud Ophiolitic Complex (BOC) in the island of Masbate in the Central Philippines. Mapping of the western limb of the island revealed that only the upper crustal section of the BOC is exposed in this area. Geochemically, the pillow basalts are characterized by transitional mid-oceanic ridge basalt-island arc tholeiitic compositions. Gravity surveys yielded low Bouguer anomaly values that are consistent with the highly dismembered nature of the BOC. Short wavelength, high amplitude magnetic anomalies registered across the study area are attributed to shallow magnetic sources. This is taken to support the model that the ophiolitic complex occurs as thin crustal slivers that are not deeply-rooted in the mantle. Comparing BOC with other ophiolites in the Central Philippines, such as those in the islands of Sibuyan, Leyte and Bohol, suggests the possibility of a common or contiguous source for similarly-aged and geochemically composed crust-mantle sequences in the region. [ABSTRACT FROM AUTHOR]

Northwest Panay consists of two terranes that form part of the Central Philippine collision zone: Buruanga Peninsula and Antique Range. The Buruanga Peninsula consists of a Jurassic chert-clastic-limestone sequence, typical of oceanic plate stratigraphy of the Palawan Micro-continental Block. The Antique Range is characterized by Antique Ophiolite Complex peridotites and Miocene volcanic and clastic rocks, representing obducted oceanic crust that serves as the oceanic leading edge of the collision with the Philippine Mobile Belt. The Nabas Fault is identified as the boundary between the two terranes. This study employed the gravity method to characterize the Northwest Panay subsurface structure. Results indicate higher Bouguer anomaly values for Buruanga Peninsula than those for Antique Range, separated by a sudden decrease in gravity values toward the east-southeast (ESE) direction. Forward gravity data modeling indicates the presence of an underlying basaltic subducted slab in the Buruanga Peninsula. Furthermore, the Nabas Fault is characterized as an east-dipping thrust structure formed by Buruanga Peninsula basement leading edge subduction beneath Antique Range. Additional geophysical constraints were provided by shallow seismic refraction and electrical resistivity surveys. Results from both methods delineated the shallow subsurface signature of the Nabas Fault buried beneath alluvium deposits. The gravity, seismic refraction and electrical resistivity methods were consistent in identifying the Nabas Fault as the terrane boundary between the Buruanga Peninsula and the Antique Range. The three geophysical methods helped constrain the subsurface configuration in Northwest Panay. [ABSTRACT FROM AUTHOR]