My World GIS

My World is a Geographic Information System (GIS) designed specifically for use in middle school through college classrooms. My World provides a carefully selected subset of the features of a professional GIS environment. These features include multiple geographic projections, table and map views of data, distance-measurement tools, buffering and query operations, and customizable map display. They have been selected to provide the greatest value to students without overwhelming them with complexity. The features are accessed through a supportive interface designed with the needs of students and teachers in mind. My World can import data from the industry-standard shapefile format, as well as from tab and comma-delimited text files. In the future, it will be able to communicate directly with GPS-enabled handheld devices. The web site features links to download My World GIS software along with sample data and documentation. This resource is part of the Using Global Data Sets collection. http://serc.carleton.edu/NAGTWorkshops/globaldata02/

Estimating Hurricane-Force Winds

This resource provides an abstract: To better measure hurricane-force winds, the authors studied various types of synthetic aperture radar (SAR) wind retrieval schemes applied to the high winds observed in 2004 during Hurricane Ivan. They found that the newly-developed Cmod5 empirical geophysical model function (GMF) outperforms the commonly used Cmod4 GMF in analyzing these high winds. They suggest that continued analysis of SAR wind mapping under extreme wind conditions can be a useful tool for hurricane tracking and prediction.

Hurricane intensification may be related to eyewall precipitation

This resource provides an abstract. The authors used weather surveillance radars along the United States coast to study the frequency of tall precipitation in order to quantify the relationship between hurricane wind intensification and tall precipitation cells along hurricane eyewalls. Their analysis showed that if the frequency of tall precipitation in the eyewall is at least 33 percent then there was an 82 percent chance that hurricane winds will intensify. If this threshold was not met, the chance of wind intensification dropped to 17 percent. The authors suggest that this height-frequency threshold could aid forecasters during future hurricane seasons.

Corrections of the Indian gauge data used for early assessments of the great 26 December 2004 earthquake

This resource is an abstract. This study re-evaluates slip velocity over the region of the December 26, 2004 Sumatra-Andaman earthquake. Using new data, the authors found that a mixed mode of slip occurred in the region, with half the total slip occurring seismically in less than five minutes after the rupture arrival, and the rest developing over the next 30 minutes.

Tsunami warnings using ocean circulation models

This resource is an abstract. This study uses numerical models that take advantage of digital seismometry and satellite radar altimetry to shed light on tsunami source and formation mechanisms. The authors used data from the 26 December 2004 tsunami to generate a 3-D ocean circulation model that they compared it to actual wave propagation recorded by satellites. It was found that the model consistently matches the observed phenomenon. The authors suggest that ocean-general-circulation-models coupled with fresh earthquake data can provide earlier warning to coastal communities at risk.

Listening to the 2004 Indian Ocean tsunami quake

This resource is an abstract. This study tracks the movement of the rupture that caused the December 26, 2004 Indian Ocean tsunami by comparing recordings of sound waves from five sensors located around the Indian Ocean. The data were used to triangulate the location of sound wave source. Results indicated that the rupture first moved northwest at 2.4 kilometers per second along the Sunda trench then slowed to 1.5 kilometers per second around 600 kilometers from the earthquake's epicenter. The author indicates that the slower speed of the rupture was unusual for an earthquake caused by a rupture close to the surface.

A tsunami warning system for the Indian Ocean

This resource is an abstract. Using tidal gauge data from the time of the 2004 Indian Ocean tsunami, the authors were able to reconstruct the height and speed of the waves and the time it took them to reach coastal regions. Readings from the tidal gauges could have given advance warning to some areas hit by the tsunami, had a warning system been in place. Suggestions for creating a tsunami warning system for the Indian Ocean region are given.

Tsunami "shadows" may allow remote detection of tidal waves

This resource provides an abstract. This study investigates tsunami shadows, extended dark strips on the ocean surface before a tsunami. Such shadows are found to result from an air-sea interaction induced by tsunami-related atmospheric disturbances. Results suggest that remote surface water observations can be used to detect deep ocean tsunamis via their shadows and thus provide significantly more reliable and earlier warning before the large waves strike vulnerable shores.

How volcanic eruptions cause tsunamis

This study investigates the effect of pyroclastic flows on tsunami generation. The authors analyzed several possible mechanisms that occur when the particle rich flows encounter water and conclude that the volume and density of the basal flow has a close correlation with the wave's amplitude and wavelength, which can be used to model the water movement in lakes, bays and oceans.

Predicting catastrophic earthquakes

This resource provides an abstract. This article discusses a method based on the magnitude-frequency distribution of previous earthquakes in a region. It is used to examine the probability of a small earthquake growing into a catastrophic one. When a small earthquake is detected in a region where a catastrophic one is expected, early warning systems can be modified to determine the probability that this earthquake will grow in magnitude. It was found that if the observed earthquake magnitude reaches 6.5, the estimated probability that the final magnitude will reach 7.5 is between 25 and 41 percent.