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Letmi Dwiridal
Universitas Negeri Padang
Agriculture, Biological Sciences & Forestry Humanities Astronomy Automotive Engineering Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Engineering Environmental Science Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mathematics Mechanical Engineering Physics Social Sciences Other

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Analysis of the Comfort Level of Climate in the Padang Coastal Tourism Area Using the Holiday Climate Index (HCI) Method Randy; Nofi Yendri Sudiar; Ahmad Fauzi; Letmi Dwiridal
Journal of Climate Change Society Vol. 1 No. 1 (2023)
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/jccs/Vol1-iss1/3

Abstract

Padang city is one of the regions of Indonesia that has potential in the tourism sector, one of which is beach tourism. The tourism sector is one of the largest sectors and the main mainstay for the economy in various countries, including Indonesia. Countries that rely on the tourism sector must pay attention to several factors that attract tourists, one of which is climate comfort. Climate information is a major factor in choosing a tourist trip. This study aims to analyze the level of climate comfort in the coastal tourism area of Padang City using the Holiday Climate Index (HCI) method. HCI uses climate parameters such as air temperature, humidity, wind speed, rainfall, and cloud cover. HCI calculation data in the form of observation data obtained from the Meteorology Climatology Geophysics Agency (BMKG) station at Minangkabau International Airport and the Teluk Bayur Maritime Meteorology Station from 2011-2020, direct measurement data from August to September, and questionnaires. The results of the HCI analysis show that the city of Padang is comfortable throughout the year, with the HCI value in the range of 58.6-71.6 which is categorized as acceptable to very good. The results obtained through direct measurements also obtained comfortable results throughout the day with HCI values in the range of 70-80. Perceptions of tourists interviewed also stated that overall tourists felt comfortable with the percentage of respondents as much as 74.1%. HCI can be used as a source of information to determine the value of climate comfort in tourist areas.
Thermal Comfort Index Analysis of Padang City Coastal Tour-ism Area Using the Physiological Equivalent Temperature (PET) Method Sadinda Tsania Suhada; Nofi Yendri Sudiar; Hamdi; Letmi Dwiridal
Journal of Climate Change Society Vol. 1 No. 1 (2023)
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/jccs/Vol1-iss1/5

Abstract

This study aims to determine the category of comfortable thermal sensation in traveling based on the value of the Physiological Equivalent Temperature (PET) thermal index. The research sites were selected in Padang Beach (PP), Air Manis Beach (PAM) and Nirwana Beach (PN). Calculation of perception of comfort using questionnaire data to visitors. PET calculation data is sourced from the Meteorology, Climatology and Geophysics Agency (BMKG) in 2011-2020 and direct measurement data. The results show that the PET thermal sensation category for the Padang City coastal area throughout the year (2011-2020) is included in the "warm" category for tourism activities. Likewise, direct measurements show the "very hot" category with a PET value of 40.3ºC. However, interviews with visitors showed that the overall comfort condition was “neutral” (62%). This is due to environmental conditions that provide a comfortable effect on visitors. The majority of visitors were interviewed under the auspices. Although the measured air temperature is classified as "high", the effects of trees, walking paths and rest areas make visitors feel comfortable.
Analysis of Extreme Rainfall in Padang City Based on The Influence of MJO and IOD in The Period 1991-2020 Cindy Magriza Putri; Nofi Yendri Sudiar; Hamdi; Letmi Dwiridal
Journal of Experimental and Applied Physics Vol 1 No 2 (2023): September Edition
Publisher : Department of Physics, Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/jeap.v1i2.15

Abstract

Rainfall above normal can be categorized as extreme rainfall. Extreme rainfall can be caused by various factors, such as global, local, and regional factors. Some regional factors that influence rainfall are the Madden Julian Oscillation (MJO) and the Indian Ocean Dipole (IOD). Padang City has high rainfall intensity which can result in extreme rainfall. The lack of adequate disaster mitigation results in flood disasters when extreme rainfall occurs. Therefore, this research aims to determine normal rainfall, extreme rainfall trends and the relationship between the MJO and IOD phenomena with the frequency of extreme rainfall in Padang City. This information is needed for future disaster mitigation planning. The method used is the time series method and statistical correlation test. Based on the results of the analysis, it is known that Padang City is an area with an equatorial rain type, where the highest rainfall occurs in November with a value of 512 mm and the lowest in May with a value of 268 mm. The trend in extreme rainfall tends to decrease with regression coefficient values ​​of 0.0412 and 0.0708. There is a significant relationship between the number of negative IOD events and the frequency of extreme rainfall with a correlation coefficient of 0.483 and 0.403 which indicates a moderate correlation. There is no significant correlation between the number of strong MJO events in Phases 3 and 4 and the frequency of extreme rainfall, with a correlation coefficient of -0.038 – 0.105.
Analysis Of Changes In Seismic Rate (Seismic Rate Change) Based On Seismotektonic Spatial Distribution Of Bengkulu Area Fadhil Ramadhani; Syafriani; Hamdi; Letmi Dwiridal
Journal of Experimental and Applied Physics Vol 1 No 2 (2023): September Edition
Publisher : Department of Physics, Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/jeap.v1i2.17

Abstract

Bengkulu Province has a high level of seismicity with significant earthquakes preceded by the phenomenon of decreased seismic activity (seismic quiescence) which can be seen through observing changes in seismic rate in an area based on the spatial distribution of z values. This study uses data from the USGS website for the period 1925-2021 to study seismic rates changes based on the spatial distribution of z values. In this study there are seven research focus zones, five major earthquake zones 1934 (7.0 SR), 1943 (7.0 SR), 2000 (7.0 SR), 2001 (7.0 SR), 2007 (7.7 SR), as well as two seismic activity zones with coordinates -5.6° to -4° south latitude and 101.6° to 103.4° east longitude and a seismic gap zone with coordinates –4.2° to -2.5° South latitude and 102.6° to 104.5° East longitude. The observation result show that before the earthquake occurred in the period 1925-2021, Before the earthquake, there had been a seismic quiescence phenomena. Four years before 2021, the seismic quiescence phenomena occurs in high seismic activity zones., while the seismic gap area occurs seven years before 2021. Overall, the seismic activity analysis result in Bengkulu province area shows an increase and decrease in seismic activity simultaneously in several different areas. This should be suspected of being the beginning of a significant earthquake in the future.
Microzonation Analysis of Soil Vulnerability Index of Sumani Region As Part of The Sumatra Fault System Using Microtremor: Analisis Mikrozonasi Indeks Kerentanan Tanah Daerah Sumani Sebagai Bagian Dari Sistem Sesar Sumatera Menggunakan Metoda Mikrotremor Lingga Ayunda Pradipta; Syafriani Syafriani; Hamdi Hamdi; Letmi Dwiridal
Journal of Experimental and Applied Physics Vol 1 No 3 (2023): December Edition
Publisher : Department of Physics, Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/jeap.v1i3.30

Abstract

West Sumatra is a province located on the west coast of the island of Sumatra in the middle which has four active fault segments. Nagari Sumani is part of the Sumani Segment line, which makes Nagari Sumani very vulnerable to earthquakes. Efforts are needed too . reduce the impact of the earthquake in Nagari Sumani. This study aims to determine the value of soil vulnerability index (Kg) and soil vulnerability index microzonation (Kg) in Nagari Sumani, specifically Jorong Pinjangek and Jorong Guci, in the area of ​​the Sumani Segment route. The microtremor method of measuring this microtremor can determine the dominant frequency value (f0), amplification factor (A0), and soil susceptibility index value (Kg). Microtremor data was used to obtain the H/V curve at each point of data collection using Geopsy software. Seismic vulnerability index microzonation is carried out using software Surfers 13. The results of this study indicate that the seismic vulnerability index in Nagari Sumani ranges from 3.65 x 10-6 s2/cm to 99.51 x 10-6 s2/cm which has low, medium, to high categories. The results of microzonation of low soil susceptibility index (Kg) are at points 1,2,7, and 8 with a value range of 3.65 x 10-6 s2/cm to 41.02 x 10-6 s2/cm, the medium category is in points 3 and 5 with a value range of 50.02 x 10-6 s2/cm to 54.23 x 10-6 s2/cm, while the high category is at points 4 and 6 with a value range of 63.32 x 10-6 s2/cm to 99.51 x 10-6 s2/cm .
Analysis Of The Relationship Of Rare Earth Elements To Magnetic Minerals In Pumice In The Southern Tip Of Lampung Province Rifqa Hayati; Hamdi Hamdi; Letmi Dwiridal; Harman Amir
Journal of Experimental and Applied Physics Vol 1 No 3 (2023): December Edition
Publisher : Department of Physics, Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/jeap.v1i3.31

Abstract

In advanced clean energy technologies, rare earth elements (REEs) are an important component. The position of rare earth elements in the future is increasingly strategic so it is necessary to strive to be developed sustainably. At the southern tip of Lampung province, rare earth elements are not yet known. The aims of this study were to analyze the magnetic susceptibility value, composition and percentage of rare earth elements, and the relationship of rare earth elements with magnetic mineral concentrations in pumice at the southern tip of Lampung Province. The method employed is rock magnetic method with Bartington Magnetic Susceptibility Meter Type B and X-Ray Fluorescence. Pumice in the southern region of Lampung Province has diverse magnetic susceptibility values, pumice from Bandar Lampung City has the highest magnetic susceptibility value, while the lowest is in South Lampung Regency. This pumice has antiferromagnetic and ferrimagnetic magnetic properties, and was found to have almost no superparamagnetic grains and also found a mixture of superparamagnetic and coarse grains. The composition of rare earth elements contained in pumice at the southern tip of Lampung Province obtained 3 rare earth elements, samples from Bandar Lampung City contained europium, cerium, and yttrium elements and samples from South Lampung Regency contained europium and yttrium elements. Rare earth elements and magnetic mineral concentration have a relationship, the obtained values decrease with increasing percentage of rare earth elements.
Analysis Of The Relationship Of Rare Earth Elements To Magnetic Mineral Concentrations In Pumice Around Sigura-Gura Dian Laila Fitri; Hamdi Hamdi; Ahmad Fauzi; Letmi Dwiridal
Journal of Experimental and Applied Physics Vol 1 No 3 (2023): December Edition
Publisher : Department of Physics, Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar

Abstract

Rare earth elements are part of one of the strategic minerals and are included in the "critical minerals". Concentrations of rare earth elements are economically precious deposits that can be used as mining commodities. Pumice is the result of volcanic eruptions and it is one of the minerals containing the rare earth elements, one of which is found in Sigura-Gura, North Sumatra. The research aims to determine the composition of rare earth elements, the relationship between rare earth elements and magnetic mineral concentration, and to determine the concentration of magnetic minerals in pumice in Sigura-gura. The method employed is rock magnetic method with Bartington Magnetic Susceptibility Meter Sensor type B (MS2B), and X-Ray Fluorescence (XRF). Results indicated that Sigura-Gura pumice samples, and Sigura-Gura Waterfall have quite varied magnetic mineral concentrations with a range of values from 111,3 x 10-8m3/kg to 349,9 x 10-8m3/kg, with antiferromagnetic magnetic properties and grain types with almost no SP grains. Samples of Sigura-Gura pumice contain elements of Eu, Ce, and Y, while samples from Sigura-Gura Waterfall contain elements of Eu and Y. There is a correlation between the amount of magnetic minerals and rare elements, and the more elements are present in a sample, the lower the value that is produce, and the greater the percentage of elements obtained, the smaller (%) is obtained.
Analysis Of Earthquake Fault Type In 2022 in the Mentawai Region Using Waveform Inversion Method Ika Sri Fahmi; Syafriani Syafriani; Hamdi Hamdi; Letmi Dwiridal
Journal of Experimental and Applied Physics Vol 1 No 3 (2023): December Edition
Publisher : Department of Physics, Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/jeap.v1i3.34

Abstract

Indonesia is a country prone to earthquake disasters, because Indonesia is located in the collision area between plates, and one of the areas in Indonesia where plate movements often occur is Mentawai. Analysis of waveform data on the 2022 earthquake in the Mentawai region was carried out to determine the type of fault. The data used in this research is local seismic data downloaded from webdc.eu. Seismic data was analyzed using waveform inversion method implemented in ISOLA program. In the ISOLA program, data processing is carried out which includes: inputting 3-component seismic data, earthquake info events, selecting stations, green functions, performing inversion, and displaying results in the form of tensor moment values, strike, dip, and rake values. From the data analysis, the moment tensor value is obtained with the range of each component of M11 is -8.348 to -3.673, M22 is 0.710 to -2.037, M33 is 7.639 to 5.710, M31 is 2.050 to 3.761, M32 is 3.484 to -5.672, M12 is -2.751 to 2.455. Then the inversion results obtained in the form of fault parameters, namely strike, dip, and rake for two nodals that will be analyzed to determine the fault plane. Based on the moment tensor value, it is found that the type of earthquake fault in 2022 in Mentawai region is dominated by reverse fault and oblique fault patterns.
Pengaruh Deklinasi Dan Asensiorekta (Ra) Matahari Terhadap Suhu Ekstrim Di Sumatera Barat Tahun 2020-2024 Aditya Zein Oktavianto; Letmi Dwiridal; Harman Amir; Hidayati Hidayati
Journal of Science, Technology, and Innovation Vol 1 No 3 (2026): : April: Inventa: Journal of Science, Technology, and Innovation
Publisher : CV SCRIPTA INTELEKTUAL MANDIRI

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.65310/ezyxrb29

Abstract

This study investigates the influence of solar declination and right ascension on extreme temperature variability in West Sumatra during the 2020–2024 period using a quantitative empirical framework. Monthly climatological observations were integrated with astronomical parameters calculated through high-precision algorithms to construct a harmonically structured time series dataset. The results reveal that solar declination primarily governs the amplitude of seasonal temperature variation, while right ascension regulates temporal synchronization, producing observable phase shifts between astronomical forcing and atmospheric response. Harmonic analysis demonstrates that these relationships extend beyond linear correlations by capturing periodic patterns characterized by amplitude and phase metrics. Furthermore, residual components indicate the presence of external modulators, particularly sea surface temperature anomalies and large-scale climate variability, which alter the magnitude and timing of extreme temperature events. The combined analytical approach confirms that tropical atmospheric dynamics are shaped by interactions between deterministic astronomical cycles and stochastic environmental influences, offering a more robust basis for predictive climatological modeling and advancing the understanding of solar–atmosphere coupling in equatorial regions.  
Estimation of Earthquake Intensity and Peak Ground Acceleration in West Java Using the MC Guire and the Lin & Lee Method Resi Silvianis; Syafriani; Letmi Dwiridal; Zulhendra
Kappa Journal Vol 8 No 3 (2024): Kappa Journal
Publisher : Universitas Hamzanwadi

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.29408/kpj.v8i3.28095

Abstract

Abstract:  West Java province was in a subduction zone and fault zone (slip fault), which caused earthquakes. Therefore, it was necessary to research estimates of maximum ground acceleration in West Java to mitigate earthquake disasters. This research also aimed to determine the value of ground acceleration and earthquake intensity and to determine the distribution map using the McGuire method and the Lin & Lee method. The data used were earthquake data for 1950-2023 with a magnitude > 5 SR. From processing this data, the maximum ground acceleration value in West Java ranged between 10.14722-195.3540 gal, and the maximum intensity value was IV-VI MMI using the Mc Guire method. Meanwhile, for the Lin & Lee method, it ranged between 6.6512 to 49.24599 gal. Of the two methods, the largest maximum ground acceleration value was located in Cianjur Regency, which was due to its proximity to the Cimandiri fault and the geological conditions in the area.
Co-Authors - Asrizal - Hamdi Aditya Zein Oktavianto Ahmad Fauzi Akmam Akmam Angeline Chika Rorensia Anisa Rahmi Anisa Rahmi Ardilla Nofri Yuwanda Ardilla Nofri Yuwanda Cindy Magriza Putri Dessri Mai Syarif Dian Laila Fitri Dwi Anisa Visgun Dwi Anisa Visgus Eka Fitri Eko Muda Setiawan Elka Fitri Enora Fadhil Ramadhani Fahmi Rahmatia Fajri Syukur Rahmatullah Fandu Alfadilah Fanny Rahmatina Rahim Fatni Mufit Festiyed Gusmita Cahnia Putri Hamdi Hamdi Rifai Harman Amir Hidayati Hidayati Hilmi Rizki Anjani Hufri Hufri Ika Sri Fahmi Ikhsan Buyung Arifin Juliana Dekriani Lingga Ayunda Pradipta Mia Nova Isnia Gara Miftahul Jannah nabila aulia rahma Nadya Fitra Kurnia Najmil Khaira Nofi Yendri Sudiar Putra, Amali Putri Nurhaliza Ramli Ramli Randy Ratnawulan . Renol Afrizon Resi Silvianis Rifqa Hayati Riza Rahmayuni Riza Rahmayuni Sadinda Tsania Suhada Silvi Yulia Sari Silvia Irani Sugeng Nugroho Syafriani Syafriani Syafriani Syahrul Gunawan Trio Junira Fernando Yenni Darvina Yunita Syafitri Yurnetti Yurnetti Zulhendra Zulhendra Zulhendra