Hamzah Latief

TSUNAMI MITIGATION EFFORTS WITH pTA IN WEST SUMATRA PROVINCE, INDONESIA

This paper describes tsunami disaster mitigation in the West Sumatra region with participatory technology assessment (pTA), which promotes direct interaction among member and experts to discuss issues and reach consensus for mitigation through provision of information and knowledge of science and technology. Two areas were examined: Padang, the capital city; and Painan city, a town in southern West Sumatra Province, Indonesia. Tsunami have damaged these areas at least three times: in 1797, a 5–10-m-high tsunami wave height hit the area; in 1833, a 3–4-m-high tsunami came; and in 2007, an 8.4 Mw earthquake generated a local tsunami with maximum wave height of 1.5 m, as observed near Painan. Because of the high level of tsunami risk resulting from its flat topographic conditions, their respective populations of 820,000 people and 15,000 people are developing tsunami mitigation efforts with support of national institutions and international experts. These cities had different starting points and approaches. Efforts were introduced to produce official tsunami hazards maps. Insights from these lessons and ideas arising from the ongoing process after the 2007 South Sumatra and 2009 Padang earthquakes are discussed herein.

An evaluation of onshore digital elevation models for modeling tsunami inundation zones

A sensitivity study is undertaken to assess the utility of different onshore digital elevation models (DEM) for simulating the extent of tsunami inundation using case studies from two locations in Indonesia. We compare airborne IFSAR, ASTER and SRTM against high resolution LiDAR and stereo-camera data in locations with different coastal morphologies. Tsunami inundation extents modelled with airborne IFSAR DEMs are comparable with those modelled with the higher resolution datasets and are also consistent with historical run-up data, where available. Large vertical errors and poor resolution of the coastline in the ASTER and SRTM elevation datasets cause the modelled inundation extent to be much less compared with the other datasets and observations. Therefore ASTER and SRTM should not be used to underpin tsunami inundation models. a model mesh resolution of 25 m was sufficient for estimating the inundated area when using elevation data with high vertical accuracy in the case studies presented here. Differences in modelled inundation between digital terrain models (DTM) and digital surface models (DSM) for LiDAR and IFSAR are greater than differences between the two data types. Models using DTM may overestimate inundation while those using DSM may underestimate inundation when a constant Manning’s roughness value is used. We recommend using DTM for modelling tsunami inundation extent with further work needed to resolve the scale at which surface roughness should be parameterised.

Assessing tsunami hazard using heterogeneous slip models in the Mentawai Islands, Indonesia

Abstract Tsunami hazard maps are generated for the coastline of the Mentawai Islands, West Sumatra, Indonesia, to support evacuation and disaster response planning. A random heterogeneous slip generator is used to forward model a suite of earthquake rupture scenarios on the Mentawai Segment of the Sunda Subduction Zone. Up to 1000 rupture models that fit constraints provided by coral and geodetic records of coseismic vertical deformation from major earthquakes in 1797, 1833 and 2007 are used to model inundation and to define a maximum inundation zone that envelopes all of these scenarios. Comparison with single-scenario hazard assessments developed by experts and agreed through scientific consensus shows that there is value in modelling a suite of scenarios in order to obtain a more robust and conservative estimate of potential inundated areas. Although both the model presented here and the single-scenario models are based on assumptions about the characteristics of future events using knowledge of past events, by sampling a range of plausible outcomes we gain a more robust estimate of which areas may be inundated during a tsunami within the bounds of the assumptions applied.

Probabilistic Seismic and Tsunami Hazard Analysis for Design Criteria and Disaster Mitigation in Rehabilitation and Reconstruction of a Coastal area in City of Banda Aceh

A Rehabilitation and reconstruction process for coastal area of city of Banda Aceh post Great Sumatra (Mw = 9.3) earthquake requires both seismic and tsunami hazards design criteria. A case study to develop design criteria of a coastal sub-district site in the effort of disaster mitigation is presented. The case study consists of probabilistic seismic and tsunami hazard analysis. The potential of both subduction and shallow crustal faults is considered in the seismic hazard analysis. The subduction source zones are considered as a seismic source for the tsunami hazard analysis. Some site-classification analyses were conducted to estimate level of ground surface acceleration. The analyses were based on collection of shear wave velocity data from a set of geotechnical subsurface exploration and spectral analysis of surface wave survey. Likewise, tsunami inundation maps generated from probabilistic tsunami hazard analysis was also developed. The maps were developed through tsunami and run-up numerical modeling associated with its earthquake probabilities. Both the seismic and tsunami hazard criteria are recommended as a basis for design criteria as part of the disaster mitigation effort in the currently undergoing rehabilitation and reconstruction process, as well as for long-term development of the case-study site.

Development of a Wireless Sensor Network for Temperature and Humidity Monitoring

The development of a wireless sensor network system for temperature and humidity monitoring is described. The system is composed of two main parts, namely an end device and a coordinator. The end device consists of an SHT10 sensor, an XBee Pro RF module, an ATMega8535 microcontroller, and a battery. The coordinator consists of an XBee Pro RF module and an SIM900 GSM module. The temperature and humidity data were sent by the end device to the coordinator and they were forwarded to the web server via GPRS communication using the SIM900 GSM module. In order to the data stored in the database can be accessed in real time via the internet, a web server is developed by using CodeIgniter (CI). It was shown that each end device can communicate very well with the coordinator. Moreover, the data are received in accordance with the timing of delivery was given.

Development of a simple low-scale solar simulator and its light distribution

A simple low-scale solar simulator was developed. Three different lamps, which are conventional lightbulb, softone lightbulb, and halogen lamp, were employed as light sources. The halogen lamp, in fact, gave better intensity compared to the other lamps in which its intensity is closer to the field-measured sun intensity. In addition to measuring the light intensity distribution inside the simulator, simulation was also done using the Monte Carlo method. It was found that the Monte Carlo simulation fit very well the experimental data. Moreover, the light was centralized beneath the light source and well distributed inside the chamber. The intensity along the horizontal plane varied according to its position. The developed system can therefore be used for simulating the real sunlight very well.

Web-Based Surface Level Measuring System Employing Ultrasonic Sensors and GSM/GPRS-Based Communication

Water surface level should get special attention as water can cause disasters such as flood when its surface exceeds a certain level. A real time early warning system to monitor water surface level is necessary for avoiding severe effects of flood to human life. A web-based water level measuring system using an ultrasonic sensor can be an alternative choice for developing the early warning system. It is known that the system has advantages in the installation and maintenance compared to other systems. This paper discusses the design of a water level measuring system integrated with an internet web server. Ultrasonic sensors are used to measure the water surface level. A GSM / GPRS-based communication system is applied for sending measured water levels to a web server. The results indicate that the measurement data are in accordance with the water levels manually obtained. The results also show that the system works real time.

Modelling of historical tsunami in Eastern Indonesia: 1674 Ambon and 1992 Flores case studies

In order to reliably assess tsunami hazard in eastern Indonesia, we need to understand how historical events were generated. Here we consider two such events: the 1674 Ambon and the 1992 Flores tsunamis. Firstly, Ambon Island suffered a devastating earthquake that generated a tsunami with 100 m run-up height on the north coast of the island in 1674. However, there is no known active fault around the island capable of generating such a gigantic wave. Rumphius’ report describes that the initial wave was coming from three villages that collapsed immediately after the earthquake with width as far as a musket shot. Moreover, a very high tsunami was only observed locally. We suspect that a submarine landslide was the main cause of the gigantic tsunami on the north side of Ambon Island. Unfortunately, there is no data available to confirm if landslide have occurred in this region. Secondly, several tsunami source models for the 1992 Flores event have been suggested. However, the fault strike is quite different c...

A Simple Accelerometer Calibrator

High possibility of earthquake could lead to the high number of victims caused by it. It also can cause other hazards such as tsunami, landslide, etc. In that case it requires a system that can examine the earthquake occurrence. Some possible system to detect earthquake is by creating a vibration sensor system using accelerometer. However, the output of the system is usually put in the form of acceleration data. Therefore, a calibrator system for accelerometer to sense the vibration is needed. In this study, a simple accelerometer calibrator has been developed using 12 V DC motor, optocoupler, Liquid Crystal Display (LCD) and AVR 328 microcontroller as controller system. The system uses the Pulse Wave Modulation (PWM) form microcontroller to control the motor rotational speed as response to vibration frequency. The frequency of vibration was read by optocoupler and then those data was used as feedback to the system. The results show that the systems could control the rotational speed and the vibration frequencies in accordance with the defined PWM.

Probabilistic seismic and tsunami hazard analysis for design criteria development of a coastal area in the city of Banda Aceh

Both seismic and tsunami hazards design criteria are essential input to the rehabilitation and long-term development of city of Banda Aceh Post Sumatra 2004 (M w=9.3) disaster. A case study to develop design criteria for future disaster mitigation of the area is presented. The pilot study consists of probabilistic seismic and tsunami hazard analysis. Results of the probabilistic seismic hazard analysis indicates that peak ground acceleration at baserock for 10 and 2% probability of exceedance in 50 years is 0.3 and 0.55 g, respectively. The analysis also provides spectral values at short (T=0.2 s) and long period (T=1.0 s) motions. Some non-linear time-domain earthquake response analyses for soft, medium, and hard site-class were conducted to recommend design response spectra for each site-class. In addition, tsunami inundation maps generated from probabilistic tsunami hazard analysis were developed through tsunami wave propagation analysis and run-up numerical modeling associated with its probability of tsunamigenic earthquake source potential. Both the seismic and tsunami hazard curve and design criteria are recommended as contribution of this study for design criteria, as part of the disaster mitigation effort in the development process of the city. The methodology developed herein could be applied to other seismic and tsunami disaster potential areas.